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A novel voltage-mode universal filter composed of two terminal active devices
Accepted Manuscript Regular paper A Novel Voltage-Mode Universal Filter Composed of Two Terminal Active Devices Erkan Yuce, Serdar Tez PII: DOI: Reference:
S1434-8411(17)31710-7 https://doi.org/10.1016/j.aeue.2018.01.010 AEUE 52199
To appear in:
International Journal of Electronics and Communications
Received Date: Accepted Date:
15 July 2017 13 January 2018
Please cite this article as: E. Yuce, S. Tez, A Novel Voltage-Mode Universal Filter Composed of Two Terminal Active Devices, International Journal of Electronics and Communications (2018), doi: https://doi.org/10.1016/ j.aeue.2018.01.010
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Accepted Version of AEUE_2017_1550
A Novel Voltage-Mode Universal Filter Composed of Two Terminal Active Devices Erkan Yuce* Department of Electrical & Electronics Engineering, Pamukkale University, 20160, Kinikli-Denizli, Turkey e-mail: [email protected] Serdar Tez Department of Electrical & Electronics Engineering, Pamukkale University, 20160, Kinikli-Denizli, Turkey e-mail: [email protected] * Corresponding author Abstract: A novel voltage-mode (VM) universal filter is proposed in this work. A voltage follower (VF) and a negative impedance converter (NIC) which are two terminal active elements are used in the implementation of the proposed filter. Also, two capacitors and three resistors are employed in the proposed filter as passive circuit elements. On the other hand, each of the VF and NIC can be easily constructed by using a plus-type second-generation current conveyor. One of the main advantages of the proposed filter is the feature of low output impedance resulting in easy cascadability with other VM circuits. Moreover, the quality factor of the proposed filter can be easily adjusted by changing value of only one of the resistors without disturbing its angular resonance frequency. Nonetheless, it requires a single resistive matching condition for proper circuit operation and a unity gain inverting amplifier for only all-pass filter responses. A number of simulation results are achieved by using 0.13 μm IBM CMOS technology parameters with ±0.75 V DC power supply voltages. Power consumption of the proposed filter is approximately found as 3.65 mW through SPICE simulations. Furthermore, experimental test results are included to confirm the theory.
Keywords: Voltage-mode, Universal filter, Low output impedance, Voltage follower, Negative impedance converter.
1. Introduction Voltage-mode (VM) analog filters [1] have been attracting attention due to the applications in various research areas such as signal processing, telecommunications and control engineering. Most of the applications demand different performance criteria such as low supply voltages, low power consumption, universality, orthogonality, cascadability, a number 1
of active and passive components as low as possible as well as temperature independent circuit characteristics. Therefore, there is an ongoing research effort in the literature to design analog filters [2]. In the realization of analog filters, various kinds of active devices such as second-generation current conveyors (CCIIs) [3], negative impedance converters (NICs), voltage followers (VFs) and current followers (CFs) [4]-[16] have been used. The filters proposed in [4] and [5] do not have universal and orthogonal circuit characteristics as well as low output impedance. Furthermore, the number of the capacitors is not canonical in [4]. Although the feature of the universal circuit behavior is ensured in [6][8], they suffer from lack of having low output impedance and orthogonal filter configurations. Moreover, there is a need for using the amplifiers to obtain the certain filter characteristics such as the notch filter (NF) and all-pass (AP) filter in [7]. The feature of low output impedance is ensured in [9]-[16]. However, the drawbacks of the proposed circuits in [9]-[11] are the lack of universal and orthogonal filter configurations. Moreover, characteristics of the filter in [10] are affected by the temperature changes since its internal structure is implemented with BJTs. For the circuit presented in [12], the number of capacitors is not canonical. The circuit orthogonality is provided in [13]; however, it needs passive component choices to obtain certain filter responses such as low-pass (LP), band-pass (BP), high-pass (HP) and NF responses. Some important features such as the universality, orthogonality and low output impedance are the main advantages of the filters mentioned in [14]-[16] despite the expense of the use of a number of active and passive components. On the other hand, a high-order filter employing only a minimum number of VFs was previously proposed in [17] but it can realize only LP response. Therefore, there is a need to realize a novel second-order VM universal filter having the properties such as the universality, orthogonality and low output impedance with a reduced number of active and passive circuit elements. This paper reports a novel VM biquadratic universal filter implemented with only two active elements including a current NIC (INIC) and a VF as well as five passive elements involving three resistors and two capacitors. In addition, to include a reduced number of the active and passive circuit elements, the proposed analog filter also provides not only low output impedance yielding easy cascadability with other VM structures but also universal as well as orthogonal filter configuration. The quality factor (Q) of the proposed filter circuit can be controlled orthogonally by changing value of only one resistor without disturbing its resonance frequency (fo). Moreover, electronic tunability can be achieved by replacing MOS transistor based floating voltage controlled resistors reported in [18] and [19] instead of three 2
resistors of the proposed filter. However, the proposed biquad filter requires a unity gain inverting amplifier to provide only AP filter responses and a single resistive matching condition. A number of simulation results are carried out by using 0.13 μm IBM CMOS technology parameters with ±0.75 V DC power supply voltages. Power dissipation of the proposed filter is nearly found as 3.65 mW through SPICE simulations. Moreover, experimental test results are given to verify the theory. This paper is organized as follows: After the first section, the plus-type CCII (CCII+), VF, INIC and the proposed VM universal filter are introduced in section 2. In Section 3, the parasitic impedance effects on the proposed filter are investigated. The simulation and experimental test results are respectively given in Sections 4 and 5. The Figure-of-Merit (FoM) is calculated in Section 6. Section 7 concludes the paper.
2. The Proposed Voltage-Mode Universal Filter In this study, the proposed VM biquadratic universal filter are realized by using an INIC and a VF which are basically obtained from the CCII+ by taking necessary connections. Fig. 1 shows the CCII+ circuit symbol, and it can be defined by the following matrix equation given in [2] and [3]: (1)
Vx
Vy
Ix Iy
X
CCII Z+
Iz+
Vz+
Y
Fig. 1. Circuit symbol of the CCII+. where β and α are respectively frequency dependent non-ideal voltage and current gains, and they are ideally equal to unity. Fig. 2 (a) and (b) show the necessary connection among X, Y and Z+ terminals of the CCII+ to form a INIC and a VF, respectively.
Z+
Y
Vx
Ix
Iy
Vy
Vy
Iy
Y CCII X Z+
CCII X
(a)
(b) 3
Ix
Vx
Fig. 2. (a) INIC realization from the CCII+ (b) VF realization from the CCII+. Figs. 3 (a) and (b) demonstrate the circuit symbols of the INIC and VF, and they can be respectively defined in [3] and [17] by the following matrix equations: (2a)
(2b)
Vx
Ix
Iy X INIC Y
Vy
Vy
Iy
Y VF
(a)
X
Ix
Vx
(b)
Fig. 3. (a) Circuit symbol of the INIC and (b) Circuit symbol of the VF. Fig. 4 shows the proposed second-order VM universal filter.
C1
V1 V2
X
Y VF (2)
Vout
R1 R2 C2 X
INIC (1) Y
R3
V3 Fig. 4. The proposed second-order voltage-mode universal filter.
The output voltage of the proposed filter without considering any matching conditions can be expressed as
4
(3)
When the non-ideal gains are included, the equation in (3) turns to the following expression: (4) It can be possible to make further analysis on the output voltage of the proposed filter when the passive component matching condition is taken into account. The output voltage of the proposed filter can be expressed with respect to the input voltage selections. If the resistors R2 = R3 = R are chosen in equation (3), then, the output voltage can be simplified and ideally expressed as (5)
The equation in (5) can also be used to determine fo and Q of the proposed filter. Thus, fo and Q are respectively given in the following equations: (6a) (6b)
It is seen from the equations in (6) that fo and Q can be controlled orthogonally by the value of the resistor R1. The passive component sensitivities with respect to fo and Q are evaluated as follows: (7.a) (7.b) It is observed from equations (7) that the values of passive component sensitivities with respect to fo and Q are no more than unity in magnitude. From equation (5), the output voltage of the proposed filter can be easily obtained with appropriate input voltage selections. If the input voltages are selected as V1 = V2 = 0V and V3 = Vin, then the response of the proposed filter is LP. It is necessary to choose the input voltages as V2 = Vin and V1 = V3 = 0V to obtain the BP response. For the HP filter response, the input voltages should be chosen as V2 = V3 = 0V and V1 = Vin. Necessary conditions for the input voltages are V2 = 0V and V1 = V3 = Vin for the NF response. If the input voltages are
5
selected as V1 = -V2 = V3 = Vin, the response of the proposed filter is AP. However, the proposed filter needs a unity gain inverting amplifier for the AP responses.
3. Influence of the Parasitic Impedances on the Filter Performances The CCII+ with its parasitic impedances is denoted in Fig. 5 where Rx is the X terminal parasitic resistor and Cy is the Y terminal parasitic capacitor. Moreover, Rz and Cz are respectively parasitic resistor and capacitor of the Z terminal. Hence, matrix equation of the CCII+ can be defined by including parasitic impedances as follows: Vx 1 I sC y y I z 0
0 Vy I 0 x sCz 1 / Rz Vz
Rx 0 1
(8)
For simplicity, if only the X terminal parasitic resistors with R3 = R2 + Rx1 are taken into account, the output voltage in equation (5) turns to
Iz Vy
Vz
Z
IY
Y
CCII+ X
Rz
Cz
Cy Rx Ix Vx
Fig. 5. CCII+ with its parasitic impedances.
(9) The values of Rx1 and Rx2 are important to determine the performance characteristics of the proposed filter such as fo and Q. However, one can easily see that if the values of Rx1 and Rx2 are small enough, their influences on the proposed filter performance can be ignored, and the parameters fo and Q almost remain the same as given in equation (6). If only the Z and the Y terminal parasitic impedances with R3 = R2 = R are considered, the output voltage in equation (5) converts to (10) Although the parasitic capacitor values are small enough, the performance of the proposed filter can be mainly affected by the value of the Z terminal parasitic resistor of the INIC. In 6
order to decrease this effect, the cascade current mirrors can be used in the internal structure of the INIC. Furthermore, the effects of the parasitic impedances on the proposed filter can be reduced by using the other methods given in literature [6], [20]-[23]. 4. Simulation Results The proposed VM universal filter in Fig. 4 is simulated with SPICE program in which 0.13 µm IBM CMOS technology parameters [24] are employed. The internal structure of the CCII+ [25] is shown in Fig. 6 and used in simulations where the aspect ratios (W/L) of the MOS transistors are given in Table 1. Furthermore, the design of the CCII+ demonstrated in Fig. 6 is capable of self-biasing property. In the simulations, symmetrical DC power supply voltages of the CCII+ shown in Fig. 6 are chosen as ±0.75 V. Parasitic impedances of the CCII+ in Fig. 6 are evaluated as Rx ≅ 348 mΩ, Rz ≅ 13.72 kΩ, Cz ≅ 26.42 fF and Cy ≅ 3.55 fF through SPICE simulations. Passive components of the proposed second-order universal filter circuit shown in Fig. 4 are chosen as R1 = R2 = R3 = 250 Ω and C1 = C2 = 50 pF resulting in fo = 12.732 MHz and Q = 1. Frequency domain simulation results of the proposed filter for the LP, BP and HP responses are given in Fig. 7. Further analyses are also performed on the phase and gain responses of the proposed NF and AP filter. The obtained frequency domain results for the NF and AP filter are shown in Fig. 8 and Fig. 9, respectively. Time domain AP filter responses at resonance frequency are represented in Fig. 10 in which a sinusoidal input voltage signal with 50 mV peak is applied. Moreover, total harmonic distortion (THD) variations versus applied peak sinusoidal input voltage signals for the AP filter at resonance frequency are denoted in Fig. 11. It is observed from Fig. 11 that THD is low enough when the input voltage is between 0.8 mV peak and 90 mV peak. Thus, dynamic range (DR) is approximately evaluated as 41.02 dB. Moreover, input and corresponding output noises for the AP filter against frequency are demonstrated in Fig. 12. Transient temperature analysis for the AP filter is depicted in Fig. 13 where temperature is changed from -50oC to 100oC by a step size of 50oC. In addition, a sinusoidal input voltage signal with 50mV peak is applied at resonance frequency in Fig. 13. A transient Monte Carlo (MC) analysis with a hundred runs is performed for the AP filter in which only values of all of the passive elements are changed by 10% uniformly. Fig. 14 shows the results of the transient MC analysis obtained by applying a sinusoidal input voltage signal at resonance frequency with 50 mV peak. Also, histograms for the phase of the all-pass filter is given in Fig. 15 where sigma and mean are approximately evaluated as 12.2 and -181.5o, respectively.
7
Symmetrical DC power supply voltages are varied from ±0.75 V to ±1 V by a step size of 0.05 V; accordingly, the resultant time domain all-pass filter responses are given in Fig. 16 where the same values of the passive components given before are used. In order to demonstrate cascadability of the proposed filter, a sixth-order band-pass filter demonstrated in Fig. 17 is derived from the proposed second-order band-pass filter shown in Fig. 4. The transfer function of any sixth-order band-pass filter can be defined as [26] s3 H ( s) K
o1o 2o 3 Q1Q2 Q3
2 o1 s s o21 s 2 o 2 s o22 s 2 o 3 s o23 Q1 Q2 Q3
(11)
In equation (11), K is the gain, Q1, Q2 and Q3 are the quality factors as well as ωo1, ωo2 and ωo3 are the angular resonance frequencies. If the values of all of the nine resistors and all of the six capacitors are respectively chosen as 250 Ω and 50 pF, the values of the quality factors, gain and resonance frequency are evaluated as Q1 = Q2 = Q3 = 1, K = 1 and fo = fo1 = fo2 = fo3 = 12.732 MHz, respectively. Also, the simulation results shown in Fig. 18 are obtained from the sixth-order band-pass filter example in Fig. 17.
Table 1. Dimensions of the MOS transistors of the CCII+ given in Fig. 6. Transistor Name M1, M2, M3, M4, M5, M8, M9 M7, M10, M14, M15, M16 M12, M13 M11 M6
8
W(μm) / L(μm) 65 / 0.52 26 / 0.52 39 / 0.52 260 / 0.52 130 / 0.52
VDD
VDD
VDD
VDD
VDD M2
M1 M4
M3
M5 M6 M7
Y
M8
M10
M9
X
Z
M11 M12
M13 M15
M14
VSS
VSS
VSS
VSS
M16 VSS
Fig. 6. The internal structure of the CCII+ [25].
Fig. 7. Ideal and simulation results of the gains of the low-pass, band-pass and high-pass responses with respect to frequency.
9
Fig. 8. Ideal and simulation phase and gain response results of the notch filter versus frequency.
Fig. 9. Ideal and simulation phase and gain response results of the all-pass filter with respect to frequency.
10
Fig. 10. Time domain responses of the proposed all-pass filter at resonance frequency.
Fig. 11. Total harmonic distortion variations with respect to applied peak values of sinusoidal input voltage signals.
11
Fig. 12. Input and associated output noises for the all-pass filter versus frequency.
Fig. 13. Transient temperature analysis for the all-pass filter.
12
Fig. 14. A transient Monte Carlo analysis results for the all-pass filter.
Fig. 15. Histograms for the phase of the all-pass filter at resonance frequency.
13
Fig. 16. Time domain all-pass responses due to changes in power supply voltages. C5 Y VF
C3 C1
Vin
X
R7
(4) X
R8
R4
(2)
C6 R5
R1
C4 R2 C2 X
X
X
INIC (5) Y
INIC (3) Y
INIC (1)
Vout
(6) Y VF
Y VF
X
R9
Y
R6 R3
Fig. 17. A sixth-order band-pass filter derived from the proposed second-order voltage-mode universal filter demonstrated in Fig. 4.
14
Fig. 18. Ideal and simulation responses of the sixth-order band-pass filter shown in Fig. 17.
5. Experimental Test Results In order to accomplish experimental tests, two commercially available active devices such as AD844s [27] with DC symmetrical power supply voltages of ±12 V are employed instead of the VF and INIC. As an example, in the implementation of the proposed circuit, the passive circuit element values are chosen as C1 = C2 = 1nF and R2 = R3 = 4.7 kΩ resulting in the resonance frequency nearly fo ≅ 33.86 kHz. Moreover, the experimental test results are achieved for various values of R1 yielding different Q values. The utilized resistor values of R1 are 2.2 kΩ, 4.7 kΩ, 10 kΩ and 20 kΩ. Thus, the quality factor values corresponding to each of the resistor values of R1 are respectively Q ≅ 0.47, Q = 1, Q ≅ 2.13 and Q ≅ 4.25. Also, the orthogonality feature of the proposed BP filter is demonstrated in Fig. 19. Also, ideal and experimental LP and HP responses are demonstrated in Fig. 20. Apart from these, the layout of the printed circuit board (PCB) and the fabricated PCB used in experimental tests of the proposed filter are shown in Figs. 21(a) and 21(b), respectively. It is observed from the simulation results shown in Figs. 7-16 and 18 and experimental test results given in Figs. 19 and 20 that ideal, simulation and experimental results are in good agreement; however, a slight discrepancy among them can be attributed to frequency dependent non-ideal gains and parasitic impedances of the active devices.
15
Fig. 19. Both simulation and experimental band-pass responses of the proposed filter so as to show orthogonality.
Fig. 20. Both ideal and experimental low-pass and high pass responses of the proposed filter.
16
(a)
(b) Fig. 21. (a) The layout of the printed circuit board, (b) The fabricated printed circuit board used in experimental tests of the proposed filter. 6. The Figure-of-Merit For a second-order VM universal filter, the FoM was defined in [28] with the following equation:
FoM=
Dynamic Range Power Dissipation×Number of Active Devices
(12)
From equation in (12), the FoM of the proposed filter is approximately computed as 5619.2. Apart from this, Table 2 presents a comparison among the two terminal active building block (ABB) based second-order VM filters reported in the literature [4]-[16] and the second-order VM universal filter proposed in this work.
Table 2. A comparison among the two terminal ABB based second-order voltage-mode filters reported in the literature [4]-[16] and this study. 17
Floating
Grounded
Floating
Grounded
Universality
Orthogonality
Low Output Impedance
Technology
DC Power Supplies (V)
Power Dissipation (mW)
Figure of Merit
[4]
CF (1)
2
0
3
0
No
No
No
NA
NA
NA
NA
[5]
VF (1), CF (1)
3
0
2
0
No
No
No
AD844
NA
NA
NA
[6]
NIC (1)
2
0
2
0
Yes
No
No
0.35 µm
±1.5
1.36
17707
[7]
NIC (1)
2
0
2
0
Yes *
No
No
BJT
±2.5
NA
NA
[8]
VF (2), CF (1)
3
0
2
0
Yes
No
No
AD844
NA
NA
NA
[9] (LP)
VF (1)
3
1
2
1
No
No
Yes
S4741A
NA
NA
NA
[10]
VC (1)
2
1
1
1
No
No
Yes
BJT
±5
30
NA
[11]
VF (2)
2
0
2
0
No
No
Yes
0.13 µm
±0.75
0.523
24000
[12]
VF (1)
3
0
3
0
No
NA
Yes
NA
NA
NA
NA
[13]
VF (2), CF (2)
2-3
1
1-2
1
No
Yes
Yes
NA
NA
NA
NA
[14]
VF (4), CF (4)
5
1
0
2
Yes
Yes
Yes
1.2 µm
±5
NA
NA
[15]
VF (3), CF (3)
6
2
0
2
Yes
Yes
Yes
AD844
NA
NA
NA
[16]
VF (2), CF (4)
4
1
1
2
Yes
Yes
Yes
NA
NA
NA
NA
This study
INIC (1), VF (1)
3
0
2
0
Yes
Yes
Yes
0.13 µm
±0.75
3.65
5619.2
(# of ABBs)
ABB Type
# of Capacitors
References
# of Resistors
NA: not available, *: amplifiers are required for NF and AP filter responses
7. Conclusion A novel second-order VM universal filter composed of a VF and an INIC as active elements is proposed in this study. Due to the nature of the proposed filter, the active devices have two terminals and can be easily constructed by employing two CCII+s. Moreover, the proposed filter employs two capacitors and three resistors as the passive elements. One of the main advantages of the proposed filter is to include a reduced number of active and passive circuit elements. The other important properties of the proposed filter are both to have low output impedance resulting in easy cascadability with other VM topologies and to provide orthogonal control of the angular resonance frequency and the quality factor. However, it needs a single resistive matching constraint for proper circuit operation and a unity gain inverting amplifier for only all-pass filter responses. A number of experimental test implementations and SPICE simulation results confirm the theory well as expected. 18
References [1] K. Su, Analog Filters, 2nd Edition, Kluwer Academic Publishers, 2002. [2] G. Ferri, N. C. Guerrini, Low voltage, low power CMOS current conveyors, Springer, 2003. [3] A. S. Sedra, K. C. Smith, A second-generation current conveyor and its applications, IEEE Transactions on Circuit Theory, vol. 17, pp. 132-134, 1970. [4] S.-I. Liu, J.-J. Chen, J.-H. Tsay, New insensitive notch and allpass filters with single current follower, Electronics Letters, vol. 27, no. 19, pp. 1712-1713, 1991. [5] R.-M. Weng, J.-R. Lai, M.-H. Lee, New universal biquad filters using only two unity-gain cells, International Journal of Electronics, vol. 87, no. 1, pp. 57-61, 2000. [6] E. Yuce, Negative impedance converter with reduced non-ideal gain and parasitic impedance effects, IEEE Transactions on Circuits and Systems I - Regular Papers, vol. 55, no. 1, pp. 276-283, 2008. [7] M. Sagbas, M. Koksal, Voltage-mode three-input single-output multifunction filters employing minimum number of components, Frequenz, vol. 61, no. 3-4, pp. 87-93, 2007. [8] R.-M. Weng, M.-H. Lee, Novel universal biquad filters using only three followers, International Journal of Electronics, vol. 82, no. 6, pp. 621-628, 1997. [9] A. S. Sedra, A class of stable active filters using unity-gain voltage followers, IEEE Journal of Solid-State Circuits, vol. 7, no. 4, pp. 311-315, 1972. [10] A. Fabre, J.-L. Houle, Voltage-mode and current-mode Sallen-Key implementations based on translinear conveyors, IEE Proceedings-G, vol. 139, no. 4, pp. 491-497, 1992. [11] F. Yucel, E. Yuce, A new voltage-mode multifunctional filter using only two voltage followers and a minimum number of passive elements, Journal of Circuits, Systems, and Computers (JCSC), vol. 24, no. 6, 2015. [12] Y. Tsividis, Y. Papananos, Continuous-time filters using buffers with gain lower than unity, Electronics Letters, vol. 30, no. 8, pp. 629-630, 1994. [13] E. O. Gunes, F. Anday, Realization of voltage and current-mode transfer functions using unity-gain cells, International Journal of Electronics, vol. 83, no. 2, pp. 209-213, 1997. [14] S. S. Gupta, R. Senani, New voltage-model/current-mode universal biquad filter using unity-gain cells, International Journal of Electronics, vol. 93, no. 11, pp. 769-775, 2006. [15] S. Celma, J. Sabadell, P. Martinez, Universal filter using unity-gain cells, Electronics Letters, vol. 31, no. 21, pp. 1817-1818, 1995.
19
[16] K. Salama, Continuous time universal filters using unity gain cells, AEÜ, International Journal of Electronics and Communications, vol. 56, no. 5, pp. 289-292, 2002. [17] C. Acar, Nth-order lowpass voltage transfer function synthesis using CCII+s: signal-flow graph approach, Electronics Letters, vol. 32, no. 3, pp. 159-160, 1996. [18] E. Yuce, Multiplier, frequency doubler and squarer circuits based on voltage controlled resistors, International Journal of Electronics and Communications (AEÜ), vol. 65, no. 3, pp. 244-249, 2011. [19] S. A. Tekin, H. Ercan, and M. Alci, Novel low voltage CMOS current controlled floating resistor using differential pair, Radioengineering, vol. 22, no. 2, pp. 428-432, 2013. [20] S. Minaei, E. Yuce, “A simple CMOS-based inductor simulator and frequency performance improvement techniques”, International Journal of Electronics and Communications, vol. 66, pp. 884-891, 2012. [21] A. Fabre, and H. Barthelemy, “Composite second-generation current conveyor with reduced parasitic resistance”, Electronics Letters, vol. 30, no. 5, pp. 377-378, 1994. [22] G. Ferri, N. C. Guerrini and M. Diqual, CCII-based floating inductance simulator with compensated series resistance, Electronics Letters, vol. 39, pp. 1560-1562, 2003. [23] E. Yuce, and S. Minaei, Novel floating simulated inductors with wider operatingfrequency ranges, Microelectronics Journal, vol. 40, pp. 928-938, 2009. [24] E. Yuce, A single-input multiple-output voltage-mode second-order universal filter using only grounded passive components, Indian Journal of Engineering & Material Sciences, vol. 24, pp. 97-106, 2017. [25] E. Arslan, and A. Morgul, Wideband self-biased CMOS CCII, Research in Microelectronics and Electronics, 2008. PRIME 2008. PhD., Istanbul, 2008, pp. 217-220. doi: 10.1109/RME.2008.4595764. [26] S. Franco, Design with operational amplifiers and analog integrated circuits, third edition, the McGraw-Hill, 2002. [27] AD844
60MHz
monolithic
Op
amp
http://www.analog.com/media/en/technical-
documentation/data-sheets/AD844.pdf. [28] A. Abaci, and E. Yuce, A new DVCC+ based second-order current-mode universal filter consisting of only grounded capacitors, Journal of Circuits, Systems, and Computers (JCSC), vol. 26, no. 9, 18 pages, 2017.
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A Novel Voltage-Mode Universal Filter Composed of Two Terminal Active Devices
Erkan Yuce was born in 1969 in Nigde, Turkey. He received the B.Sc. degree from Middle East Technical University, the M.Sc. degree from Pamukkale University and the PhD. degree from Bogazici University all in Electrical and Electronics Engineering in 1994, 1998 and 2006, respectively. He is currently an Associative Professor at the Electrical and Electronics Engineering Department of Pamukkale University. His current research interests include analog circuits, active filters, synthetic inductors and CMOS based circuits. He is the author or co-author of about 150 papers published in scientific journals or conference proceedings.
Serdar Tez received the B.S and the M.S. degrees in the Physics Department from the Suleyman Demirel University, Isparta, Turkey, in 2004 and 2006, respectively. He joined the METU-MEMS Research and Applications Center in 2008. He received the Ph.D. degree in the Micro and Nanotechnology Graduate Program from the Middle East Technical University (METU), Ankara, Turkey, in 2014, with the work on MEMS capacitive three-axis accelerometers. Currently, he is with the Department of Electrical and Electronic Engineering, Pamukkale University, Denizli, 20160 Turkey. His current research interests are the design, simulation, and fabrication methods of micro structures and active filters. He is the author or co-author of about 6 papers published in scientific journals or conference proceedings.
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S1434-8411(17)31710-7 https://doi.org/10.1016/j.aeue.2018.01.010 AEUE 52199
To appear in:
International Journal of Electronics and Communications
Received Date: Accepted Date:
15 July 2017 13 January 2018
Please cite this article as: E. Yuce, S. Tez, A Novel Voltage-Mode Universal Filter Composed of Two Terminal Active Devices, International Journal of Electronics and Communications (2018), doi: https://doi.org/10.1016/ j.aeue.2018.01.010
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Accepted Version of AEUE_2017_1550
A Novel Voltage-Mode Universal Filter Composed of Two Terminal Active Devices Erkan Yuce* Department of Electrical & Electronics Engineering, Pamukkale University, 20160, Kinikli-Denizli, Turkey e-mail: [email protected] Serdar Tez Department of Electrical & Electronics Engineering, Pamukkale University, 20160, Kinikli-Denizli, Turkey e-mail: [email protected] * Corresponding author Abstract: A novel voltage-mode (VM) universal filter is proposed in this work. A voltage follower (VF) and a negative impedance converter (NIC) which are two terminal active elements are used in the implementation of the proposed filter. Also, two capacitors and three resistors are employed in the proposed filter as passive circuit elements. On the other hand, each of the VF and NIC can be easily constructed by using a plus-type second-generation current conveyor. One of the main advantages of the proposed filter is the feature of low output impedance resulting in easy cascadability with other VM circuits. Moreover, the quality factor of the proposed filter can be easily adjusted by changing value of only one of the resistors without disturbing its angular resonance frequency. Nonetheless, it requires a single resistive matching condition for proper circuit operation and a unity gain inverting amplifier for only all-pass filter responses. A number of simulation results are achieved by using 0.13 μm IBM CMOS technology parameters with ±0.75 V DC power supply voltages. Power consumption of the proposed filter is approximately found as 3.65 mW through SPICE simulations. Furthermore, experimental test results are included to confirm the theory.
Keywords: Voltage-mode, Universal filter, Low output impedance, Voltage follower, Negative impedance converter.
1. Introduction Voltage-mode (VM) analog filters [1] have been attracting attention due to the applications in various research areas such as signal processing, telecommunications and control engineering. Most of the applications demand different performance criteria such as low supply voltages, low power consumption, universality, orthogonality, cascadability, a number 1
of active and passive components as low as possible as well as temperature independent circuit characteristics. Therefore, there is an ongoing research effort in the literature to design analog filters [2]. In the realization of analog filters, various kinds of active devices such as second-generation current conveyors (CCIIs) [3], negative impedance converters (NICs), voltage followers (VFs) and current followers (CFs) [4]-[16] have been used. The filters proposed in [4] and [5] do not have universal and orthogonal circuit characteristics as well as low output impedance. Furthermore, the number of the capacitors is not canonical in [4]. Although the feature of the universal circuit behavior is ensured in [6][8], they suffer from lack of having low output impedance and orthogonal filter configurations. Moreover, there is a need for using the amplifiers to obtain the certain filter characteristics such as the notch filter (NF) and all-pass (AP) filter in [7]. The feature of low output impedance is ensured in [9]-[16]. However, the drawbacks of the proposed circuits in [9]-[11] are the lack of universal and orthogonal filter configurations. Moreover, characteristics of the filter in [10] are affected by the temperature changes since its internal structure is implemented with BJTs. For the circuit presented in [12], the number of capacitors is not canonical. The circuit orthogonality is provided in [13]; however, it needs passive component choices to obtain certain filter responses such as low-pass (LP), band-pass (BP), high-pass (HP) and NF responses. Some important features such as the universality, orthogonality and low output impedance are the main advantages of the filters mentioned in [14]-[16] despite the expense of the use of a number of active and passive components. On the other hand, a high-order filter employing only a minimum number of VFs was previously proposed in [17] but it can realize only LP response. Therefore, there is a need to realize a novel second-order VM universal filter having the properties such as the universality, orthogonality and low output impedance with a reduced number of active and passive circuit elements. This paper reports a novel VM biquadratic universal filter implemented with only two active elements including a current NIC (INIC) and a VF as well as five passive elements involving three resistors and two capacitors. In addition, to include a reduced number of the active and passive circuit elements, the proposed analog filter also provides not only low output impedance yielding easy cascadability with other VM structures but also universal as well as orthogonal filter configuration. The quality factor (Q) of the proposed filter circuit can be controlled orthogonally by changing value of only one resistor without disturbing its resonance frequency (fo). Moreover, electronic tunability can be achieved by replacing MOS transistor based floating voltage controlled resistors reported in [18] and [19] instead of three 2
resistors of the proposed filter. However, the proposed biquad filter requires a unity gain inverting amplifier to provide only AP filter responses and a single resistive matching condition. A number of simulation results are carried out by using 0.13 μm IBM CMOS technology parameters with ±0.75 V DC power supply voltages. Power dissipation of the proposed filter is nearly found as 3.65 mW through SPICE simulations. Moreover, experimental test results are given to verify the theory. This paper is organized as follows: After the first section, the plus-type CCII (CCII+), VF, INIC and the proposed VM universal filter are introduced in section 2. In Section 3, the parasitic impedance effects on the proposed filter are investigated. The simulation and experimental test results are respectively given in Sections 4 and 5. The Figure-of-Merit (FoM) is calculated in Section 6. Section 7 concludes the paper.
2. The Proposed Voltage-Mode Universal Filter In this study, the proposed VM biquadratic universal filter are realized by using an INIC and a VF which are basically obtained from the CCII+ by taking necessary connections. Fig. 1 shows the CCII+ circuit symbol, and it can be defined by the following matrix equation given in [2] and [3]: (1)
Vx
Vy
Ix Iy
X
CCII Z+
Iz+
Vz+
Y
Fig. 1. Circuit symbol of the CCII+. where β and α are respectively frequency dependent non-ideal voltage and current gains, and they are ideally equal to unity. Fig. 2 (a) and (b) show the necessary connection among X, Y and Z+ terminals of the CCII+ to form a INIC and a VF, respectively.
Z+
Y
Vx
Ix
Iy
Vy
Vy
Iy
Y CCII X Z+
CCII X
(a)
(b) 3
Ix
Vx
Fig. 2. (a) INIC realization from the CCII+ (b) VF realization from the CCII+. Figs. 3 (a) and (b) demonstrate the circuit symbols of the INIC and VF, and they can be respectively defined in [3] and [17] by the following matrix equations: (2a)
(2b)
Vx
Ix
Iy X INIC Y
Vy
Vy
Iy
Y VF
(a)
X
Ix
Vx
(b)
Fig. 3. (a) Circuit symbol of the INIC and (b) Circuit symbol of the VF. Fig. 4 shows the proposed second-order VM universal filter.
C1
V1 V2
X
Y VF (2)
Vout
R1 R2 C2 X
INIC (1) Y
R3
V3 Fig. 4. The proposed second-order voltage-mode universal filter.
The output voltage of the proposed filter without considering any matching conditions can be expressed as
4
(3)
When the non-ideal gains are included, the equation in (3) turns to the following expression: (4) It can be possible to make further analysis on the output voltage of the proposed filter when the passive component matching condition is taken into account. The output voltage of the proposed filter can be expressed with respect to the input voltage selections. If the resistors R2 = R3 = R are chosen in equation (3), then, the output voltage can be simplified and ideally expressed as (5)
The equation in (5) can also be used to determine fo and Q of the proposed filter. Thus, fo and Q are respectively given in the following equations: (6a) (6b)
It is seen from the equations in (6) that fo and Q can be controlled orthogonally by the value of the resistor R1. The passive component sensitivities with respect to fo and Q are evaluated as follows: (7.a) (7.b) It is observed from equations (7) that the values of passive component sensitivities with respect to fo and Q are no more than unity in magnitude. From equation (5), the output voltage of the proposed filter can be easily obtained with appropriate input voltage selections. If the input voltages are selected as V1 = V2 = 0V and V3 = Vin, then the response of the proposed filter is LP. It is necessary to choose the input voltages as V2 = Vin and V1 = V3 = 0V to obtain the BP response. For the HP filter response, the input voltages should be chosen as V2 = V3 = 0V and V1 = Vin. Necessary conditions for the input voltages are V2 = 0V and V1 = V3 = Vin for the NF response. If the input voltages are
5
selected as V1 = -V2 = V3 = Vin, the response of the proposed filter is AP. However, the proposed filter needs a unity gain inverting amplifier for the AP responses.
3. Influence of the Parasitic Impedances on the Filter Performances The CCII+ with its parasitic impedances is denoted in Fig. 5 where Rx is the X terminal parasitic resistor and Cy is the Y terminal parasitic capacitor. Moreover, Rz and Cz are respectively parasitic resistor and capacitor of the Z terminal. Hence, matrix equation of the CCII+ can be defined by including parasitic impedances as follows: Vx 1 I sC y y I z 0
0 Vy I 0 x sCz 1 / Rz Vz
Rx 0 1
(8)
For simplicity, if only the X terminal parasitic resistors with R3 = R2 + Rx1 are taken into account, the output voltage in equation (5) turns to
Iz Vy
Vz
Z
IY
Y
CCII+ X
Rz
Cz
Cy Rx Ix Vx
Fig. 5. CCII+ with its parasitic impedances.
(9) The values of Rx1 and Rx2 are important to determine the performance characteristics of the proposed filter such as fo and Q. However, one can easily see that if the values of Rx1 and Rx2 are small enough, their influences on the proposed filter performance can be ignored, and the parameters fo and Q almost remain the same as given in equation (6). If only the Z and the Y terminal parasitic impedances with R3 = R2 = R are considered, the output voltage in equation (5) converts to (10) Although the parasitic capacitor values are small enough, the performance of the proposed filter can be mainly affected by the value of the Z terminal parasitic resistor of the INIC. In 6
order to decrease this effect, the cascade current mirrors can be used in the internal structure of the INIC. Furthermore, the effects of the parasitic impedances on the proposed filter can be reduced by using the other methods given in literature [6], [20]-[23]. 4. Simulation Results The proposed VM universal filter in Fig. 4 is simulated with SPICE program in which 0.13 µm IBM CMOS technology parameters [24] are employed. The internal structure of the CCII+ [25] is shown in Fig. 6 and used in simulations where the aspect ratios (W/L) of the MOS transistors are given in Table 1. Furthermore, the design of the CCII+ demonstrated in Fig. 6 is capable of self-biasing property. In the simulations, symmetrical DC power supply voltages of the CCII+ shown in Fig. 6 are chosen as ±0.75 V. Parasitic impedances of the CCII+ in Fig. 6 are evaluated as Rx ≅ 348 mΩ, Rz ≅ 13.72 kΩ, Cz ≅ 26.42 fF and Cy ≅ 3.55 fF through SPICE simulations. Passive components of the proposed second-order universal filter circuit shown in Fig. 4 are chosen as R1 = R2 = R3 = 250 Ω and C1 = C2 = 50 pF resulting in fo = 12.732 MHz and Q = 1. Frequency domain simulation results of the proposed filter for the LP, BP and HP responses are given in Fig. 7. Further analyses are also performed on the phase and gain responses of the proposed NF and AP filter. The obtained frequency domain results for the NF and AP filter are shown in Fig. 8 and Fig. 9, respectively. Time domain AP filter responses at resonance frequency are represented in Fig. 10 in which a sinusoidal input voltage signal with 50 mV peak is applied. Moreover, total harmonic distortion (THD) variations versus applied peak sinusoidal input voltage signals for the AP filter at resonance frequency are denoted in Fig. 11. It is observed from Fig. 11 that THD is low enough when the input voltage is between 0.8 mV peak and 90 mV peak. Thus, dynamic range (DR) is approximately evaluated as 41.02 dB. Moreover, input and corresponding output noises for the AP filter against frequency are demonstrated in Fig. 12. Transient temperature analysis for the AP filter is depicted in Fig. 13 where temperature is changed from -50oC to 100oC by a step size of 50oC. In addition, a sinusoidal input voltage signal with 50mV peak is applied at resonance frequency in Fig. 13. A transient Monte Carlo (MC) analysis with a hundred runs is performed for the AP filter in which only values of all of the passive elements are changed by 10% uniformly. Fig. 14 shows the results of the transient MC analysis obtained by applying a sinusoidal input voltage signal at resonance frequency with 50 mV peak. Also, histograms for the phase of the all-pass filter is given in Fig. 15 where sigma and mean are approximately evaluated as 12.2 and -181.5o, respectively.
7
Symmetrical DC power supply voltages are varied from ±0.75 V to ±1 V by a step size of 0.05 V; accordingly, the resultant time domain all-pass filter responses are given in Fig. 16 where the same values of the passive components given before are used. In order to demonstrate cascadability of the proposed filter, a sixth-order band-pass filter demonstrated in Fig. 17 is derived from the proposed second-order band-pass filter shown in Fig. 4. The transfer function of any sixth-order band-pass filter can be defined as [26] s3 H ( s) K
o1o 2o 3 Q1Q2 Q3
2 o1 s s o21 s 2 o 2 s o22 s 2 o 3 s o23 Q1 Q2 Q3
(11)
In equation (11), K is the gain, Q1, Q2 and Q3 are the quality factors as well as ωo1, ωo2 and ωo3 are the angular resonance frequencies. If the values of all of the nine resistors and all of the six capacitors are respectively chosen as 250 Ω and 50 pF, the values of the quality factors, gain and resonance frequency are evaluated as Q1 = Q2 = Q3 = 1, K = 1 and fo = fo1 = fo2 = fo3 = 12.732 MHz, respectively. Also, the simulation results shown in Fig. 18 are obtained from the sixth-order band-pass filter example in Fig. 17.
Table 1. Dimensions of the MOS transistors of the CCII+ given in Fig. 6. Transistor Name M1, M2, M3, M4, M5, M8, M9 M7, M10, M14, M15, M16 M12, M13 M11 M6
8
W(μm) / L(μm) 65 / 0.52 26 / 0.52 39 / 0.52 260 / 0.52 130 / 0.52
VDD
VDD
VDD
VDD
VDD M2
M1 M4
M3
M5 M6 M7
Y
M8
M10
M9
X
Z
M11 M12
M13 M15
M14
VSS
VSS
VSS
VSS
M16 VSS
Fig. 6. The internal structure of the CCII+ [25].
Fig. 7. Ideal and simulation results of the gains of the low-pass, band-pass and high-pass responses with respect to frequency.
9
Fig. 8. Ideal and simulation phase and gain response results of the notch filter versus frequency.
Fig. 9. Ideal and simulation phase and gain response results of the all-pass filter with respect to frequency.
10
Fig. 10. Time domain responses of the proposed all-pass filter at resonance frequency.
Fig. 11. Total harmonic distortion variations with respect to applied peak values of sinusoidal input voltage signals.
11
Fig. 12. Input and associated output noises for the all-pass filter versus frequency.
Fig. 13. Transient temperature analysis for the all-pass filter.
12
Fig. 14. A transient Monte Carlo analysis results for the all-pass filter.
Fig. 15. Histograms for the phase of the all-pass filter at resonance frequency.
13
Fig. 16. Time domain all-pass responses due to changes in power supply voltages. C5 Y VF
C3 C1
Vin
X
R7
(4) X
R8
R4
(2)
C6 R5
R1
C4 R2 C2 X
X
X
INIC (5) Y
INIC (3) Y
INIC (1)
Vout
(6) Y VF
Y VF
X
R9
Y
R6 R3
Fig. 17. A sixth-order band-pass filter derived from the proposed second-order voltage-mode universal filter demonstrated in Fig. 4.
14
Fig. 18. Ideal and simulation responses of the sixth-order band-pass filter shown in Fig. 17.
5. Experimental Test Results In order to accomplish experimental tests, two commercially available active devices such as AD844s [27] with DC symmetrical power supply voltages of ±12 V are employed instead of the VF and INIC. As an example, in the implementation of the proposed circuit, the passive circuit element values are chosen as C1 = C2 = 1nF and R2 = R3 = 4.7 kΩ resulting in the resonance frequency nearly fo ≅ 33.86 kHz. Moreover, the experimental test results are achieved for various values of R1 yielding different Q values. The utilized resistor values of R1 are 2.2 kΩ, 4.7 kΩ, 10 kΩ and 20 kΩ. Thus, the quality factor values corresponding to each of the resistor values of R1 are respectively Q ≅ 0.47, Q = 1, Q ≅ 2.13 and Q ≅ 4.25. Also, the orthogonality feature of the proposed BP filter is demonstrated in Fig. 19. Also, ideal and experimental LP and HP responses are demonstrated in Fig. 20. Apart from these, the layout of the printed circuit board (PCB) and the fabricated PCB used in experimental tests of the proposed filter are shown in Figs. 21(a) and 21(b), respectively. It is observed from the simulation results shown in Figs. 7-16 and 18 and experimental test results given in Figs. 19 and 20 that ideal, simulation and experimental results are in good agreement; however, a slight discrepancy among them can be attributed to frequency dependent non-ideal gains and parasitic impedances of the active devices.
15
Fig. 19. Both simulation and experimental band-pass responses of the proposed filter so as to show orthogonality.
Fig. 20. Both ideal and experimental low-pass and high pass responses of the proposed filter.
16
(a)
(b) Fig. 21. (a) The layout of the printed circuit board, (b) The fabricated printed circuit board used in experimental tests of the proposed filter. 6. The Figure-of-Merit For a second-order VM universal filter, the FoM was defined in [28] with the following equation:
FoM=
Dynamic Range Power Dissipation×Number of Active Devices
(12)
From equation in (12), the FoM of the proposed filter is approximately computed as 5619.2. Apart from this, Table 2 presents a comparison among the two terminal active building block (ABB) based second-order VM filters reported in the literature [4]-[16] and the second-order VM universal filter proposed in this work.
Table 2. A comparison among the two terminal ABB based second-order voltage-mode filters reported in the literature [4]-[16] and this study. 17
Floating
Grounded
Floating
Grounded
Universality
Orthogonality
Low Output Impedance
Technology
DC Power Supplies (V)
Power Dissipation (mW)
Figure of Merit
[4]
CF (1)
2
0
3
0
No
No
No
NA
NA
NA
NA
[5]
VF (1), CF (1)
3
0
2
0
No
No
No
AD844
NA
NA
NA
[6]
NIC (1)
2
0
2
0
Yes
No
No
0.35 µm
±1.5
1.36
17707
[7]
NIC (1)
2
0
2
0
Yes *
No
No
BJT
±2.5
NA
NA
[8]
VF (2), CF (1)
3
0
2
0
Yes
No
No
AD844
NA
NA
NA
[9] (LP)
VF (1)
3
1
2
1
No
No
Yes
S4741A
NA
NA
NA
[10]
VC (1)
2
1
1
1
No
No
Yes
BJT
±5
30
NA
[11]
VF (2)
2
0
2
0
No
No
Yes
0.13 µm
±0.75
0.523
24000
[12]
VF (1)
3
0
3
0
No
NA
Yes
NA
NA
NA
NA
[13]
VF (2), CF (2)
2-3
1
1-2
1
No
Yes
Yes
NA
NA
NA
NA
[14]
VF (4), CF (4)
5
1
0
2
Yes
Yes
Yes
1.2 µm
±5
NA
NA
[15]
VF (3), CF (3)
6
2
0
2
Yes
Yes
Yes
AD844
NA
NA
NA
[16]
VF (2), CF (4)
4
1
1
2
Yes
Yes
Yes
NA
NA
NA
NA
This study
INIC (1), VF (1)
3
0
2
0
Yes
Yes
Yes
0.13 µm
±0.75
3.65
5619.2
(# of ABBs)
ABB Type
# of Capacitors
References
# of Resistors
NA: not available, *: amplifiers are required for NF and AP filter responses
7. Conclusion A novel second-order VM universal filter composed of a VF and an INIC as active elements is proposed in this study. Due to the nature of the proposed filter, the active devices have two terminals and can be easily constructed by employing two CCII+s. Moreover, the proposed filter employs two capacitors and three resistors as the passive elements. One of the main advantages of the proposed filter is to include a reduced number of active and passive circuit elements. The other important properties of the proposed filter are both to have low output impedance resulting in easy cascadability with other VM topologies and to provide orthogonal control of the angular resonance frequency and the quality factor. However, it needs a single resistive matching constraint for proper circuit operation and a unity gain inverting amplifier for only all-pass filter responses. A number of experimental test implementations and SPICE simulation results confirm the theory well as expected. 18
References [1] K. Su, Analog Filters, 2nd Edition, Kluwer Academic Publishers, 2002. [2] G. Ferri, N. C. Guerrini, Low voltage, low power CMOS current conveyors, Springer, 2003. [3] A. S. Sedra, K. C. Smith, A second-generation current conveyor and its applications, IEEE Transactions on Circuit Theory, vol. 17, pp. 132-134, 1970. [4] S.-I. Liu, J.-J. Chen, J.-H. Tsay, New insensitive notch and allpass filters with single current follower, Electronics Letters, vol. 27, no. 19, pp. 1712-1713, 1991. [5] R.-M. Weng, J.-R. Lai, M.-H. Lee, New universal biquad filters using only two unity-gain cells, International Journal of Electronics, vol. 87, no. 1, pp. 57-61, 2000. [6] E. Yuce, Negative impedance converter with reduced non-ideal gain and parasitic impedance effects, IEEE Transactions on Circuits and Systems I - Regular Papers, vol. 55, no. 1, pp. 276-283, 2008. [7] M. Sagbas, M. Koksal, Voltage-mode three-input single-output multifunction filters employing minimum number of components, Frequenz, vol. 61, no. 3-4, pp. 87-93, 2007. [8] R.-M. Weng, M.-H. Lee, Novel universal biquad filters using only three followers, International Journal of Electronics, vol. 82, no. 6, pp. 621-628, 1997. [9] A. S. Sedra, A class of stable active filters using unity-gain voltage followers, IEEE Journal of Solid-State Circuits, vol. 7, no. 4, pp. 311-315, 1972. [10] A. Fabre, J.-L. Houle, Voltage-mode and current-mode Sallen-Key implementations based on translinear conveyors, IEE Proceedings-G, vol. 139, no. 4, pp. 491-497, 1992. [11] F. Yucel, E. Yuce, A new voltage-mode multifunctional filter using only two voltage followers and a minimum number of passive elements, Journal of Circuits, Systems, and Computers (JCSC), vol. 24, no. 6, 2015. [12] Y. Tsividis, Y. Papananos, Continuous-time filters using buffers with gain lower than unity, Electronics Letters, vol. 30, no. 8, pp. 629-630, 1994. [13] E. O. Gunes, F. Anday, Realization of voltage and current-mode transfer functions using unity-gain cells, International Journal of Electronics, vol. 83, no. 2, pp. 209-213, 1997. [14] S. S. Gupta, R. Senani, New voltage-model/current-mode universal biquad filter using unity-gain cells, International Journal of Electronics, vol. 93, no. 11, pp. 769-775, 2006. [15] S. Celma, J. Sabadell, P. Martinez, Universal filter using unity-gain cells, Electronics Letters, vol. 31, no. 21, pp. 1817-1818, 1995.
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[16] K. Salama, Continuous time universal filters using unity gain cells, AEÜ, International Journal of Electronics and Communications, vol. 56, no. 5, pp. 289-292, 2002. [17] C. Acar, Nth-order lowpass voltage transfer function synthesis using CCII+s: signal-flow graph approach, Electronics Letters, vol. 32, no. 3, pp. 159-160, 1996. [18] E. Yuce, Multiplier, frequency doubler and squarer circuits based on voltage controlled resistors, International Journal of Electronics and Communications (AEÜ), vol. 65, no. 3, pp. 244-249, 2011. [19] S. A. Tekin, H. Ercan, and M. Alci, Novel low voltage CMOS current controlled floating resistor using differential pair, Radioengineering, vol. 22, no. 2, pp. 428-432, 2013. [20] S. Minaei, E. Yuce, “A simple CMOS-based inductor simulator and frequency performance improvement techniques”, International Journal of Electronics and Communications, vol. 66, pp. 884-891, 2012. [21] A. Fabre, and H. Barthelemy, “Composite second-generation current conveyor with reduced parasitic resistance”, Electronics Letters, vol. 30, no. 5, pp. 377-378, 1994. [22] G. Ferri, N. C. Guerrini and M. Diqual, CCII-based floating inductance simulator with compensated series resistance, Electronics Letters, vol. 39, pp. 1560-1562, 2003. [23] E. Yuce, and S. Minaei, Novel floating simulated inductors with wider operatingfrequency ranges, Microelectronics Journal, vol. 40, pp. 928-938, 2009. [24] E. Yuce, A single-input multiple-output voltage-mode second-order universal filter using only grounded passive components, Indian Journal of Engineering & Material Sciences, vol. 24, pp. 97-106, 2017. [25] E. Arslan, and A. Morgul, Wideband self-biased CMOS CCII, Research in Microelectronics and Electronics, 2008. PRIME 2008. PhD., Istanbul, 2008, pp. 217-220. doi: 10.1109/RME.2008.4595764. [26] S. Franco, Design with operational amplifiers and analog integrated circuits, third edition, the McGraw-Hill, 2002. [27] AD844
60MHz
monolithic
Op
amp
http://www.analog.com/media/en/technical-
documentation/data-sheets/AD844.pdf. [28] A. Abaci, and E. Yuce, A new DVCC+ based second-order current-mode universal filter consisting of only grounded capacitors, Journal of Circuits, Systems, and Computers (JCSC), vol. 26, no. 9, 18 pages, 2017.
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A Novel Voltage-Mode Universal Filter Composed of Two Terminal Active Devices
Erkan Yuce was born in 1969 in Nigde, Turkey. He received the B.Sc. degree from Middle East Technical University, the M.Sc. degree from Pamukkale University and the PhD. degree from Bogazici University all in Electrical and Electronics Engineering in 1994, 1998 and 2006, respectively. He is currently an Associative Professor at the Electrical and Electronics Engineering Department of Pamukkale University. His current research interests include analog circuits, active filters, synthetic inductors and CMOS based circuits. He is the author or co-author of about 150 papers published in scientific journals or conference proceedings.
Serdar Tez received the B.S and the M.S. degrees in the Physics Department from the Suleyman Demirel University, Isparta, Turkey, in 2004 and 2006, respectively. He joined the METU-MEMS Research and Applications Center in 2008. He received the Ph.D. degree in the Micro and Nanotechnology Graduate Program from the Middle East Technical University (METU), Ankara, Turkey, in 2014, with the work on MEMS capacitive three-axis accelerometers. Currently, he is with the Department of Electrical and Electronic Engineering, Pamukkale University, Denizli, 20160 Turkey. His current research interests are the design, simulation, and fabrication methods of micro structures and active filters. He is the author or co-author of about 6 papers published in scientific journals or conference proceedings.
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