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An X-band InGaP GaAs HBT MMIC oscillator
Current Applied Physics 5 (2005) 249–253 www.elsevier.com/locate/cap
An X-band InGaP GaAs HBT MMIC oscillator q Young Gi Kim a,*, Jung Hyung Bae a, Cheol Park a, Chang Woo Kim b, Sung-Il Kim c, Byoung-Gue Min c, Jong-Min Lee c, Hong Ju Kim c, Kyung Ho Lee c a
Department of Data Communication, Anyang University, 707-113, Anyang 5-Dong, Mananku, Anyang-City, Kyungki-Do 430-714, South Korea b College of Electronic and Information Engineering, Kyung Hee University, #1 Seochon-Ri, Yongin-Si, Kyunggi-Do 449-701, South Korea c Electronics and Telecommunications Research Institute, 161 Kajong-Dong, Yusong-Gu, Taejon 305-350, South Korea Received 26 July 2003; accepted 20 September 2003 Available online 8 July 2004
Abstract This paper addresses the performance of a fully integrated low phase noise X-band oscillator fabricated by using an InGaP/GaAs HBT process with ft of 53.2 GHz. The oscillator circuit consists of a negative resistance generating circuit with base inductors, a resonating emitter circuit with micro-strip lines and a buffing resistive collector circuit with tuning diodes. The oscillator achieves 4.33 dBm output power and exhibits )121.17 dBc/Hz phase noise at 100 KHz away from 10.38 GHz oscillating frequency. This phase noise is, to our knowledge, the lowest reported for monolithic oscillators with oscillation frequencies higher than 10 GHz. The oscillator draws 36 mA current from a 6.19 V supply and occupies 0.8 mm by 0.8 mm die area. 2004 Published by Elsevier B.V. PACS: 07.50.Ek Keywords: MMIC; Oscillator; VCO; InP-HBT
1. Introduction With the development of microwave device technology, the demand for the oscillators with low phase noise and high power operating at microwave frequencies increases because the oscillator is essential component for microwave communication systems. GaAs metal semiconductor field effect transistor (MESFET) oscillators suffer from a high phase noise level which comes from 1=f noise generated mainly due to the existence of trap centers in the MESFETs [1]. Oscillators fabricated with Si bipolar transistors operate only at low frequencies despite their low phase noise. InP-based materials are mainly focused for high speed optoelectronic applications due to optimum wave length coverage for optical fiber, in addition to high electron mobility, small electron effective mass, and high peak drift velocity [2]. q
Original version presented at the 10th Korean Conference on Semiconductors, Seoul, Korea, 27–28 February 2003. * Corresponding author. Tel.: +82-31-467-0894; fax: +82-31-4670800. E-mail address: [email protected] (Y.G. Kim). 1567-1739/$ - see front matter 2004 Published by Elsevier B.V. doi:10.1016/j.cap.2003.09.022
Since the superior 1=f noise characteristics of Si bipolar transistors are due to their vertical structure with small numbers of surface recombination traps, the oscillators with GaAs based hetero-junction bipolar transistor (HBT) can offer both low phase noise and high frequency performance. The high electron mobility and the high dielectric constant make GaAs a suitable material for monolithic microwave integrated circuit (MMIC). Several leading GaAs HBT oscillator developments have already demonstrated superior phase noise performance compared to MESFET oscillators and comparable performance to silicon bipolar-based oscillators at C- and Ku-band frequencies [3,4]. Recent literature has shown that HBT oscillators offer additional performance advantages in terms of DC-RF conversion efficiency in L-band frequencies [5]. GaInP/GaAs heterojunction in the emitter region of HBT is suitable for power applications by virtue of high carrier injection efficiency. It offers lower 1=f base band noise mainly due to fewer trap-related DX centers than AlGaAs/GaAs heterojunction [6]. GaInP/GaAs HBT has also shown lower 1=f base band noise than high electron mobility transistor (HEMT) [6]. Due to these
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Y.G. Kim et al. / Current Applied Physics 5 (2005) 249–253
excellent noise characteristics the GaInP/GaAs HBT is an attractive choice for lower phase noise monolithic oscillator [7–9]. This work describes design, epitaxial structure, fabrication, and measured result of a low phase noise X-band monolithic InGaP/GaAs HBT oscillator. 2. Device structure and performances A cross-sectional view of the HBT used in the oscillator circuit is shown in Fig. 1. The epitaxial layers were grown on (1 0 0)-oriented semi-insulating GaAs substrates by using metalorganic chemical vapor deposition (MOCVD). The n- and p-type dopants were Si and C, respectively. The epitaxial layer mainly consisted of a 500 A-thick n-InGaP (n ¼ 5 1017 cm3 ) emitter layer, a 800 A thick p-GaAs (p ¼ 4 1019 cm3 ) uniform base layer, a 5000 A-thick n-GaAs (n ¼ 2 1016 cm3 ) col thick n-GaAs (n ¼ 4 1018 lector layer, and a 5000 A 3 cm ) sub-collector layer. A good surface morphology of InGaAs/GaAs enabled InGaAs emitter contact [10]. A 2 · 20 lm2 emitter configuration shown in Fig. 2 was employed as a unit cell. We measured DC and RF characteristics of the one-finger HBT devices with an
emitter area of 2 · 20 lm2 by using HP semiconductor parameter analyzer, HP 8510B network analyzer, and Cascade probe station. The devices showed an offset voltage of 0.11 V and a common-emitter current gain of 85. The breakdown voltage with open emitter (BVCBO ) was 18.8 V. The cut-off frequency, ft , and the maximum oscillation frequency, fmax , were 53 and 70 GHz, respectively, at a VCE of 2 V and Jc of 7.5 · 104 A/cm2 . 3. Oscillator circuit design Negative resistance, which is essential for a stable oscillation, is obtained by inductive feedback, Ln , at the base of the circuit as shown in Fig. 3. Then the Ln is directly AC grounded by Cd2 . Rb1 and Rb2 are self-bias resistances with stabilizing DC emitter feedback resistance, Rfb . The AC voltage drop across the Rfb is bypassed by Cbp . Cc , Lc and Cd3 are coupling capacitor, choke inductor and decoupling capacitor, respectively. If the magnitude of the negative resistance is a linearly decreasing function of amplitude of the current, the initial real load impedance, RL , and imaginary impedance, XL , for maximum oscillator power are chosen such that initial real input impedance, RIN , is negative with initial real load impedance RL and imaginary load impedance XL given by Eqs. (1) and (2) [11] jRIN j ; 3
ð1Þ
XL ¼ XIN :
ð2Þ
RL ¼
The steady state oscillation condition is established by CIN TL ¼ 1;
Fig. 1. Cross-section of an InGaP/GaAs HBT used in oscillator circuit.
Fig. 2. SEM photograph of a fabricated InGaP/GaAs HBT.
ð3Þ
where CIN and TL are input reflection and load coefficients, respectively. However, in practice the real impedance value should be as close to zero as possible to reduce the phase noise and to increase the efficiency of the oscillator circuit. Therefore, the load impedance must be almost reactive by increasing the resonator Q [5]. The change of real value of the impedance is much larger than that of the imaginary one as signal power increases in most loading circuits. In the circuit design, it was so hard to get the linear maximum oscillation condition of the Eqs. (1) and (2) at the same time that the second condition was preferred. The design value of input impedance XIN at 10.4 GHz was 8:9 j9:7 ohm. The loading resonating circuit impedance value of XL was tuned to 3:6 þ j9:7 ohm. Micro-strip line in GaAs MMIC process is made of very high conductance metal and semi-insulating substrate, which is, therefore high Q inductor in X-band frequency and precisely modeled up to mm-wave frequency. MIM capacitor has high Q also. Therefore, they were connected for the load resonating circuit.
Y.G. Kim et al. / Current Applied Physics 5 (2005) 249–253
251
Fig. 3. X-band HBT oscillator circuit.
After establishing the basic oscillating circuit by connecting the negative resistance generating circuit and resonating circuit, resistive attenuating circuit for buffering was added by Rs , Ra1 and Ra2 . Diode tuning circuit with diode1 , R1 and Cc1 was attached at the emitter of the transistor rather than at the resonating circuit. By this circuit topology, we can minimize the phase noise because the noisy tuning circuit has very small effect on the resonating circuit. Output impedance also can be tuned for better matching with this circuit. However, the tuning frequency range becomes narrow as a trade-off. As the base and collector do not have any heterojunction, the collector–base junction has fewer defects than emitter–base heterojunction in HBT. Since the defects in the PN junction are believed to be a main source of phase noise in the oscillator circuit, the former will produce better phase noise performance than the
latter. Low doped collector layer also can help wide tuning range of junction capacitance. Therefore, the reverse biased collector–base junction of the transistor was used for the tuning diode. Layout induced parasitic effect was considered using micro-strip line interconnection simulation.
Fig. 4. Photomicrograph of HBT oscillator.
Fig. 5. Output spectrum of HBT MMIC oscillator.
4. Circuit fabrication and rf performance Based on the simulation result, a monolithic oscillator circuit was fabricated as shown in Fig. 4. An InGaP/ GaAs HBT with an emitter area of 2 · 60 lm2 was used for the active device. The processed wafer was attached
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Y.G. Kim et al. / Current Applied Physics 5 (2005) 249–253
Fig. 6. Harmonic performance of HBT MMIC oscillator.
Fig. 7. Phase noise performance of HBT MMIC oscillator.
Table 1 Performance summary of previously reported oscillators and this work Oscillator process
Oscillation frequency (GHz)
Phase noise 100 kHz offset (dBc/Hz)
Phase noise 1 MHz offset (dBc/Hz)
Output power (dBm)
SiGe HBT [12] 0.25 lm CMOS [13] GaAs MESFET [4] AlGaAs/GaAs HBT [3] InAlAs/InGaAs HBT [14] InP HBT [15] InGaP/GaAs HBT [16] InGaP/GaAs HBT [9] InGaP/GaAs HBT––This work
11 10 11.4 8.3 18 20 13.5 40.8 10.39
)89 )78 )91 )112 )72 )70 )90.5 )92 )121.17
)91 )102
)21.83 )8 11.5 )14 10 )4.3 0 5.3 4.33
with back metal after being lapped to 100 lm. Total oscillator chip area was 0.8 · 0.8 mm2 . The chip was wire-bonded to a test board for free running measurements with HP8563E spectrum analyzer. The oscillator shows 4.35 dBm output power at 10.39 GHz oscillating frequency as shown in Fig. 5. The oscillator shows 47.1 MHz of frequency tuning by 4 V change. The second harmonic suppression is )23.2 dBc as shown in Fig. 6. The oscillator draws 36 mA current from a 6.19 V supply. Fig. 7 shows )121.17 dBc/Hz SSB phase noise at 100 kHz offset frequency when zero tuning diode voltage is applied. Several low noise MMIC oscillators have been reported previously and their performances are summarized in Table 1. The phase noise result is compared to other monolithic oscillators and is believed to be the best-measured phase noise result on monolithic oscillators with oscillating frequencies higher than 10 GHz, which is concluded from the comparison table.
)132 )96 )90 )113.8 )112 )123.7
5. Conclusion A very low phase noise 10.38 GHz InGaP/GaAs HBT oscillator has been demonstrated. The circuit design is based on the base inductive feedback for negative resistance and micro-strip line emitter resonator. A tuning diode circuit is attached to collector to reduce diode induced phase noise. The oscillator produces 4.33 dBm output power at 10.39 GHz oscillating frequency. The oscillator shows 47.1 MHz of frequency tuning range by 4 V change. )121.17 dBc/Hz SSB phase noises at 100 kHz offset frequency was measured, and it represents the first reported phase noise result on monolithic oscillators with oscillating frequencies higher than 10 GHz. A very low phase noise is achieved by combining excellent 1=f noise due to reduced trap-related DX-centers in InP/GaAs hetero-junction and collector tuning circuit topology, which is proposed in this paper.
Y.G. Kim et al. / Current Applied Physics 5 (2005) 249–253
Acknowledgements This work was supported by grant No. R01-2003000-10455-0 from the Basic Research Program of the Korea Science and Engineering Foundation. The authors would like to thank to IC Design Education Center for providing CAD tools.
References [1] N. Hayama, S.R. LeSage, M. Masihian, K. Honjo, IEEE MTT-S Int. Microwave Symp. Dig. 2 (1988) 679. [2] J. Chen, A. Li, Gas source molecular beam epitaxy of InP-based heterostructures for OEIC applications, Curr. Appl. Phys. 1 (2001) 419. [3] K.W. Kobayashi, D.M. Smith, C.P. Kau, A.K. Sharma, B.R. Allen, D.C. Streit, IEEE Microwave Millimeter-Wave Monolithic Circuits Symp. Dig. 107 (1996). [4] C.-H. Lee, S. Han, B. Matinpour, J. Laskar, IEEE Microwave Guided Wave Lett. 10 (2000) 325. [5] C.-H. Lee, A. Sutono, J. Laskar, IEEE Radio Wireless Conference Dig. 157 (1998).
253
[6] W.J. Ho, M.F. Chang, A. Sailer, P. Zampardi, D. Deakin, B. McDermermott, R. Pierson, J.A. Higgins, J. Waldrop, IEEE Electron Dev. Lett. 14 (1993) 572. [7] M.T. Fresina, D.A. Ahmari, P.J. Mars, Q.J. Hartmann, M. Feng, G.E. Stillman, IEEE Electron Dev. Lett. 16 (1995) 540. [8] M.S. Heins, T. Juneja, D. Caruth, M. Hattendorf, M. Feng, IEEE MTT-S Int. Microwave Symp. Dig. 1209 (2000). [9] M.S. Heins, D.W. Barlage, M.T. Fresina, D.A. Ahmari, Q.J. Hartmann, G.E. Stillman, M. Feng, IEEE MTT-S Int. Microwave Symp. Dig. 255 (1997). [10] Y.J. Park, K.M. Kim, Y.M. Park, E.K. Kim, Curr. Appl. Phys. 1 (2001) 187. [11] G. Gonzales, Microwave Amplifiers, Prentice-Hall, Englewood Cliffs, NJ, 1997 (Chapter 5). [12] A.L. Coban, K. Ahmed, C. Chang, Digest of Technical Paper, Symposium on VLSI, 119, 2001. [13] M.A. Do, R. Zhao, K.S. Yeo, J.G. Ma, Electron. Lett. 37 (2001) 102. [14] K.W. Kobayashi, L.T. Tran, A.K. Oki, T. Blok, D.C. Streit, IEEE Microwave Guided Wave Lett. 5 (1995) 311. [15] H. Djahanshahi, N. Saniei, S.P. Voinigescu, M.C. Maliepaard, C.A.T. Salama, IEEE Trans. Microwave Theory Tech. 49 (2001) 1566. [16] D.H. Beak, J.G. Kim, S. Hong, IEEE MTT-S Int. Microwave Symp. Dig. 847 (2002).
An X-band InGaP GaAs HBT MMIC oscillator q Young Gi Kim a,*, Jung Hyung Bae a, Cheol Park a, Chang Woo Kim b, Sung-Il Kim c, Byoung-Gue Min c, Jong-Min Lee c, Hong Ju Kim c, Kyung Ho Lee c a
Department of Data Communication, Anyang University, 707-113, Anyang 5-Dong, Mananku, Anyang-City, Kyungki-Do 430-714, South Korea b College of Electronic and Information Engineering, Kyung Hee University, #1 Seochon-Ri, Yongin-Si, Kyunggi-Do 449-701, South Korea c Electronics and Telecommunications Research Institute, 161 Kajong-Dong, Yusong-Gu, Taejon 305-350, South Korea Received 26 July 2003; accepted 20 September 2003 Available online 8 July 2004
Abstract This paper addresses the performance of a fully integrated low phase noise X-band oscillator fabricated by using an InGaP/GaAs HBT process with ft of 53.2 GHz. The oscillator circuit consists of a negative resistance generating circuit with base inductors, a resonating emitter circuit with micro-strip lines and a buffing resistive collector circuit with tuning diodes. The oscillator achieves 4.33 dBm output power and exhibits )121.17 dBc/Hz phase noise at 100 KHz away from 10.38 GHz oscillating frequency. This phase noise is, to our knowledge, the lowest reported for monolithic oscillators with oscillation frequencies higher than 10 GHz. The oscillator draws 36 mA current from a 6.19 V supply and occupies 0.8 mm by 0.8 mm die area. 2004 Published by Elsevier B.V. PACS: 07.50.Ek Keywords: MMIC; Oscillator; VCO; InP-HBT
1. Introduction With the development of microwave device technology, the demand for the oscillators with low phase noise and high power operating at microwave frequencies increases because the oscillator is essential component for microwave communication systems. GaAs metal semiconductor field effect transistor (MESFET) oscillators suffer from a high phase noise level which comes from 1=f noise generated mainly due to the existence of trap centers in the MESFETs [1]. Oscillators fabricated with Si bipolar transistors operate only at low frequencies despite their low phase noise. InP-based materials are mainly focused for high speed optoelectronic applications due to optimum wave length coverage for optical fiber, in addition to high electron mobility, small electron effective mass, and high peak drift velocity [2]. q
Original version presented at the 10th Korean Conference on Semiconductors, Seoul, Korea, 27–28 February 2003. * Corresponding author. Tel.: +82-31-467-0894; fax: +82-31-4670800. E-mail address: [email protected] (Y.G. Kim). 1567-1739/$ - see front matter 2004 Published by Elsevier B.V. doi:10.1016/j.cap.2003.09.022
Since the superior 1=f noise characteristics of Si bipolar transistors are due to their vertical structure with small numbers of surface recombination traps, the oscillators with GaAs based hetero-junction bipolar transistor (HBT) can offer both low phase noise and high frequency performance. The high electron mobility and the high dielectric constant make GaAs a suitable material for monolithic microwave integrated circuit (MMIC). Several leading GaAs HBT oscillator developments have already demonstrated superior phase noise performance compared to MESFET oscillators and comparable performance to silicon bipolar-based oscillators at C- and Ku-band frequencies [3,4]. Recent literature has shown that HBT oscillators offer additional performance advantages in terms of DC-RF conversion efficiency in L-band frequencies [5]. GaInP/GaAs heterojunction in the emitter region of HBT is suitable for power applications by virtue of high carrier injection efficiency. It offers lower 1=f base band noise mainly due to fewer trap-related DX centers than AlGaAs/GaAs heterojunction [6]. GaInP/GaAs HBT has also shown lower 1=f base band noise than high electron mobility transistor (HEMT) [6]. Due to these
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Y.G. Kim et al. / Current Applied Physics 5 (2005) 249–253
excellent noise characteristics the GaInP/GaAs HBT is an attractive choice for lower phase noise monolithic oscillator [7–9]. This work describes design, epitaxial structure, fabrication, and measured result of a low phase noise X-band monolithic InGaP/GaAs HBT oscillator. 2. Device structure and performances A cross-sectional view of the HBT used in the oscillator circuit is shown in Fig. 1. The epitaxial layers were grown on (1 0 0)-oriented semi-insulating GaAs substrates by using metalorganic chemical vapor deposition (MOCVD). The n- and p-type dopants were Si and C, respectively. The epitaxial layer mainly consisted of a 500 A-thick n-InGaP (n ¼ 5 1017 cm3 ) emitter layer, a 800 A thick p-GaAs (p ¼ 4 1019 cm3 ) uniform base layer, a 5000 A-thick n-GaAs (n ¼ 2 1016 cm3 ) col thick n-GaAs (n ¼ 4 1018 lector layer, and a 5000 A 3 cm ) sub-collector layer. A good surface morphology of InGaAs/GaAs enabled InGaAs emitter contact [10]. A 2 · 20 lm2 emitter configuration shown in Fig. 2 was employed as a unit cell. We measured DC and RF characteristics of the one-finger HBT devices with an
emitter area of 2 · 20 lm2 by using HP semiconductor parameter analyzer, HP 8510B network analyzer, and Cascade probe station. The devices showed an offset voltage of 0.11 V and a common-emitter current gain of 85. The breakdown voltage with open emitter (BVCBO ) was 18.8 V. The cut-off frequency, ft , and the maximum oscillation frequency, fmax , were 53 and 70 GHz, respectively, at a VCE of 2 V and Jc of 7.5 · 104 A/cm2 . 3. Oscillator circuit design Negative resistance, which is essential for a stable oscillation, is obtained by inductive feedback, Ln , at the base of the circuit as shown in Fig. 3. Then the Ln is directly AC grounded by Cd2 . Rb1 and Rb2 are self-bias resistances with stabilizing DC emitter feedback resistance, Rfb . The AC voltage drop across the Rfb is bypassed by Cbp . Cc , Lc and Cd3 are coupling capacitor, choke inductor and decoupling capacitor, respectively. If the magnitude of the negative resistance is a linearly decreasing function of amplitude of the current, the initial real load impedance, RL , and imaginary impedance, XL , for maximum oscillator power are chosen such that initial real input impedance, RIN , is negative with initial real load impedance RL and imaginary load impedance XL given by Eqs. (1) and (2) [11] jRIN j ; 3
ð1Þ
XL ¼ XIN :
ð2Þ
RL ¼
The steady state oscillation condition is established by CIN TL ¼ 1;
Fig. 1. Cross-section of an InGaP/GaAs HBT used in oscillator circuit.
Fig. 2. SEM photograph of a fabricated InGaP/GaAs HBT.
ð3Þ
where CIN and TL are input reflection and load coefficients, respectively. However, in practice the real impedance value should be as close to zero as possible to reduce the phase noise and to increase the efficiency of the oscillator circuit. Therefore, the load impedance must be almost reactive by increasing the resonator Q [5]. The change of real value of the impedance is much larger than that of the imaginary one as signal power increases in most loading circuits. In the circuit design, it was so hard to get the linear maximum oscillation condition of the Eqs. (1) and (2) at the same time that the second condition was preferred. The design value of input impedance XIN at 10.4 GHz was 8:9 j9:7 ohm. The loading resonating circuit impedance value of XL was tuned to 3:6 þ j9:7 ohm. Micro-strip line in GaAs MMIC process is made of very high conductance metal and semi-insulating substrate, which is, therefore high Q inductor in X-band frequency and precisely modeled up to mm-wave frequency. MIM capacitor has high Q also. Therefore, they were connected for the load resonating circuit.
Y.G. Kim et al. / Current Applied Physics 5 (2005) 249–253
251
Fig. 3. X-band HBT oscillator circuit.
After establishing the basic oscillating circuit by connecting the negative resistance generating circuit and resonating circuit, resistive attenuating circuit for buffering was added by Rs , Ra1 and Ra2 . Diode tuning circuit with diode1 , R1 and Cc1 was attached at the emitter of the transistor rather than at the resonating circuit. By this circuit topology, we can minimize the phase noise because the noisy tuning circuit has very small effect on the resonating circuit. Output impedance also can be tuned for better matching with this circuit. However, the tuning frequency range becomes narrow as a trade-off. As the base and collector do not have any heterojunction, the collector–base junction has fewer defects than emitter–base heterojunction in HBT. Since the defects in the PN junction are believed to be a main source of phase noise in the oscillator circuit, the former will produce better phase noise performance than the
latter. Low doped collector layer also can help wide tuning range of junction capacitance. Therefore, the reverse biased collector–base junction of the transistor was used for the tuning diode. Layout induced parasitic effect was considered using micro-strip line interconnection simulation.
Fig. 4. Photomicrograph of HBT oscillator.
Fig. 5. Output spectrum of HBT MMIC oscillator.
4. Circuit fabrication and rf performance Based on the simulation result, a monolithic oscillator circuit was fabricated as shown in Fig. 4. An InGaP/ GaAs HBT with an emitter area of 2 · 60 lm2 was used for the active device. The processed wafer was attached
252
Y.G. Kim et al. / Current Applied Physics 5 (2005) 249–253
Fig. 6. Harmonic performance of HBT MMIC oscillator.
Fig. 7. Phase noise performance of HBT MMIC oscillator.
Table 1 Performance summary of previously reported oscillators and this work Oscillator process
Oscillation frequency (GHz)
Phase noise 100 kHz offset (dBc/Hz)
Phase noise 1 MHz offset (dBc/Hz)
Output power (dBm)
SiGe HBT [12] 0.25 lm CMOS [13] GaAs MESFET [4] AlGaAs/GaAs HBT [3] InAlAs/InGaAs HBT [14] InP HBT [15] InGaP/GaAs HBT [16] InGaP/GaAs HBT [9] InGaP/GaAs HBT––This work
11 10 11.4 8.3 18 20 13.5 40.8 10.39
)89 )78 )91 )112 )72 )70 )90.5 )92 )121.17
)91 )102
)21.83 )8 11.5 )14 10 )4.3 0 5.3 4.33
with back metal after being lapped to 100 lm. Total oscillator chip area was 0.8 · 0.8 mm2 . The chip was wire-bonded to a test board for free running measurements with HP8563E spectrum analyzer. The oscillator shows 4.35 dBm output power at 10.39 GHz oscillating frequency as shown in Fig. 5. The oscillator shows 47.1 MHz of frequency tuning by 4 V change. The second harmonic suppression is )23.2 dBc as shown in Fig. 6. The oscillator draws 36 mA current from a 6.19 V supply. Fig. 7 shows )121.17 dBc/Hz SSB phase noise at 100 kHz offset frequency when zero tuning diode voltage is applied. Several low noise MMIC oscillators have been reported previously and their performances are summarized in Table 1. The phase noise result is compared to other monolithic oscillators and is believed to be the best-measured phase noise result on monolithic oscillators with oscillating frequencies higher than 10 GHz, which is concluded from the comparison table.
)132 )96 )90 )113.8 )112 )123.7
5. Conclusion A very low phase noise 10.38 GHz InGaP/GaAs HBT oscillator has been demonstrated. The circuit design is based on the base inductive feedback for negative resistance and micro-strip line emitter resonator. A tuning diode circuit is attached to collector to reduce diode induced phase noise. The oscillator produces 4.33 dBm output power at 10.39 GHz oscillating frequency. The oscillator shows 47.1 MHz of frequency tuning range by 4 V change. )121.17 dBc/Hz SSB phase noises at 100 kHz offset frequency was measured, and it represents the first reported phase noise result on monolithic oscillators with oscillating frequencies higher than 10 GHz. A very low phase noise is achieved by combining excellent 1=f noise due to reduced trap-related DX-centers in InP/GaAs hetero-junction and collector tuning circuit topology, which is proposed in this paper.
Y.G. Kim et al. / Current Applied Physics 5 (2005) 249–253
Acknowledgements This work was supported by grant No. R01-2003000-10455-0 from the Basic Research Program of the Korea Science and Engineering Foundation. The authors would like to thank to IC Design Education Center for providing CAD tools.
References [1] N. Hayama, S.R. LeSage, M. Masihian, K. Honjo, IEEE MTT-S Int. Microwave Symp. Dig. 2 (1988) 679. [2] J. Chen, A. Li, Gas source molecular beam epitaxy of InP-based heterostructures for OEIC applications, Curr. Appl. Phys. 1 (2001) 419. [3] K.W. Kobayashi, D.M. Smith, C.P. Kau, A.K. Sharma, B.R. Allen, D.C. Streit, IEEE Microwave Millimeter-Wave Monolithic Circuits Symp. Dig. 107 (1996). [4] C.-H. Lee, S. Han, B. Matinpour, J. Laskar, IEEE Microwave Guided Wave Lett. 10 (2000) 325. [5] C.-H. Lee, A. Sutono, J. Laskar, IEEE Radio Wireless Conference Dig. 157 (1998).
253
[6] W.J. Ho, M.F. Chang, A. Sailer, P. Zampardi, D. Deakin, B. McDermermott, R. Pierson, J.A. Higgins, J. Waldrop, IEEE Electron Dev. Lett. 14 (1993) 572. [7] M.T. Fresina, D.A. Ahmari, P.J. Mars, Q.J. Hartmann, M. Feng, G.E. Stillman, IEEE Electron Dev. Lett. 16 (1995) 540. [8] M.S. Heins, T. Juneja, D. Caruth, M. Hattendorf, M. Feng, IEEE MTT-S Int. Microwave Symp. Dig. 1209 (2000). [9] M.S. Heins, D.W. Barlage, M.T. Fresina, D.A. Ahmari, Q.J. Hartmann, G.E. Stillman, M. Feng, IEEE MTT-S Int. Microwave Symp. Dig. 255 (1997). [10] Y.J. Park, K.M. Kim, Y.M. Park, E.K. Kim, Curr. Appl. Phys. 1 (2001) 187. [11] G. Gonzales, Microwave Amplifiers, Prentice-Hall, Englewood Cliffs, NJ, 1997 (Chapter 5). [12] A.L. Coban, K. Ahmed, C. Chang, Digest of Technical Paper, Symposium on VLSI, 119, 2001. [13] M.A. Do, R. Zhao, K.S. Yeo, J.G. Ma, Electron. Lett. 37 (2001) 102. [14] K.W. Kobayashi, L.T. Tran, A.K. Oki, T. Blok, D.C. Streit, IEEE Microwave Guided Wave Lett. 5 (1995) 311. [15] H. Djahanshahi, N. Saniei, S.P. Voinigescu, M.C. Maliepaard, C.A.T. Salama, IEEE Trans. Microwave Theory Tech. 49 (2001) 1566. [16] D.H. Beak, J.G. Kim, S. Hong, IEEE MTT-S Int. Microwave Symp. Dig. 847 (2002).