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CDI, the bipolar LSI technology with total systems integration capability
Microelectronics and Reliability, Vol. 14, pp. 385 to 387. Pergamon Press, 1975. Printed in Great Britain
CDI, THE BIPOLAR LSI T E C H N O L O G Y WITH TOTAL SYSTEMS I N T E G R A T I O N CAPABILITY P. KaEBS The system designer of today is becoming bewildered by an ever increasing variety of semiconductor technologies (if he can get passed identifying the initials). Among bipolar technologies, isoplanar and its variants, thin epitaxy processes such as Plessey Process 3, and integrated injection logic (I2L) all aim at specific types of advantage and are normally thus limited to specific market sectors. Metal oxide semiconductor (MOS) technologies have similarly proliferated, and can conveniently be split into single channel, e.g. P-Channel, and complementary MOS technologies. These again have their specific advantages and market sectors. Ferranti CDI, however, is unique in being able to penetrate a broad market front using a single and well understood standard process. Such an approach to a variety of systems is termed Total Systems Integration, which means that frequently a complete and relatively complex system can be realised on a single chip with minimal external components. This is made possible by the many attributes of CDI, such as the performance of a bipolar process with the packing density of MOS, the combination of digital and linear circuits on the same chip (digilin), excellent device performance over a wide current range and particularly at very low currents and good speed performance with better speed power product. To substantiate these claims, some examples of CDI products and applications are given below.
Universal Four Digit Display Counter This easy to use 5 V compatible display counter contains a host of features, such as automatic zero suppression, 50 mA segment drives, 8 MHz typical count rate etc. This enables users to provide digital readout on their equipment very simply.
Linear Processor This contains three high performance amplifiers and a shunt regulator, with communications and instrumentation applications.
Machine Tool Control This application of the display counter uses a low cost optical encoder to achieve digital position measurement at a cost at which almost any lathe could use it.
Temperature Control The combination of two linear processors with the display counter provides a powerful temperature control system with digital readout of temperature. M R - - V o l . 14, No. 4 - - E
385
Vehicle Weighing System A two chip system gives dashboard display of individual axle weight and total weight, ensuring balanced loading. This paper is divided into two sections, an outline comparison of CDI [1, 2-1 and other bipolar and MOS technologies, and application examples of CDI in action. Figure 1 shows a comparison table of CDI and other representative bipolar technologies. Points to pick out are that I2L is normally grafted on to another process, so that part of the processing advantage is lost; isoplanar and related processes need tight control of both epitaxial thickness and etching, where CDI only requires good epitaxy; and the apparent disadvantage of low voltage with CDI is frequently more than offset by the ability to include a voltage regulator in a (small) part of the I.C., allowing the use of dropper resistors for deriving power. A further interesting point concerns low power logic, which relies on the low current device performance to achieve low DC currents, again favouring CDI, e.g. for watches. Figure 2 shows a similar "star chart" comparison of CDI with established P-Channel MOS and with complementary MOS. A general point, concerning bipolar vs. MOS, is that the IC realisation is conceptually far more similar to a discrete version using bipolar ICs, giving potential users more confidence. Furthermore, bipolar circuitry is far more extensive and flexible than MOS. For CDI this is particularly true, as both digital and linear circuits can be processed simultaneously with the same (non-gold) CDI process by using a feedback emitter technique. Merely by a geometry change this reduces the transistor turn-off time out of saturation from tens of nonoseconds to under 8 nS. Another useful feature of bipolar vs. MOS is the drive capability, as bipolar drives of over 100 m_A allow direct interfacing with power devices such as thyristors or relays. In addition, the functional packing density of CDI is similar to that of P-Channel MOS, and better than CMOS. These comparisons add up to the fact that CDI offers a bipolar process with all the attendant advantages including digilin [3] with the packing density of MOS. This makes for a system approach of total system capability, whereby virtually all of the system (linear, digital, low power, drive, optoelectronic, etc.) can be included on chip, often within a single I.C., with minimal external components. This is achievable with a single standard process, whose other attributes are simplicity, high reliability, and very good device performance, particularly at low currents.
386
P. KREBS SYSTEM DIAGRAM
ov o _Enable
Blanking o
Digit select outputs
Lamp test
7 segment drives
B.CD outputs
Carry output
'ltl .l,lllllll
Decimal o point Digit select sense 0
ION L O G I C ~
l
Clock frequencyO external override Transfe~
Clear o Count inhibit o Count input 0 Count up/down o
Enable
Y
GATING
Reset
Fig. 4. Block diagram of ZN1040 universal four digit display counter. This combination as used in a typical system is shown in Fig. 3. Frequently a regulator is included on chip, and inputs, which include timing components, may be digital and linear. Chip processing is also digilin, and outputs may include high drive direct interfacing to power handling devices. Display Counter Turning to more concrete applications, Fig. 4 shows the block diagram of a universal 4 digit display counter, the ZN1040E. Major features include: 4 decades of up/down synchronous counting with support latching. High current (50 mA) segment outputs, and separate B.C.D. outputs. Look ahead carry, allowing count extension by direct connection. Self scanning (true or complement) system with internal oscillator which can be synchronised. Automatic zero suppression, also catering for decimal point. Blanking, lamp test, switch-on reset. 5 V compatible system for supplies, inputs and outputs. Linear Processor Figure 5 shows the ZN417, a linear processor containing three operational amplifiers and a shunt regulator. Typical parameters are as follows: Regulator: slope impedance 1-5 fl; regulated voltage 5.3 V nominal; temperature coefficient _ 100 ppm/°C. Amplifier: Unity gain bandwidth 74 dB at 590 MHz or 94 dB at 5 MHz; input current 10 nA; input offset 2 mV.
Used as comparator: Delay 100msec; rise time 20 nsec; fall time 40 nsec. Applications of the ZN417 include communications, instrumentation and stereo preamps. U.L.A. [4, 5] Another aspect of CDI is the cellular approach offered by the U.L.A. [4]. (Uncommitted Logic Array), enabling custom L.S.I. to be made quickly and cheaply by changing only the interconnection mask. An example of the U.L.A., which enjoys wide success in a variety of applications including digilin, is the ZNA103 TV syn. pulse generator, shown in Fig. 6. Machine Tool Control Turning to more general application areas of these products, Fig. 7 shows the block schematic of a machine tool measuring system (one axis). This uses the Ferranti 24 R1-529 250 low cost optical incremental encoder, in combination with the ZN1040E. The basic system permits measurements to (~001" increments of slide movement. The resolution and speed of operation is essentially limited by the mechanics of the system as the ZN1040E can be cascaded and can handle pulse rates up to 12 MHz, equivalent to 12,000 encoder revs/sec. Temperature Controller Figure 8 shows how the ZN1040E and ZN417 may be combined to make up a temperature control system giving continuous digital indication of oven temperature. The output of the thermistor/potentiometer network--varies linearly with temperature--controls a
CDI, the Bipolar LSI Technology with Total Systems Integration Capability voltage controlled oscillator, (A1, A2, A3), whose output frequency is calibrated to the temperature, and a comparator A4 which controls the gating of the output of the zero crossing detector A5 and hence the currcut supplied to the heater. A6 is connected to form a precise three second oscillator having a defined narrow pulse width. This pulse is used to transfer and hold the digitised reading and to reset the counter. The digitised display is thus updated every three seconds. Five user adjustments are provided. Two match the slope of the thermistor network curve to the frequency voltage slope of the V.C.O., the third is used to centre the dynamic range of the V.C.O.; the fourth is used to balance the system whilst the fifth is the normal input demand potentiometer.
Motor Speed Control Another application of the C.D.I. is in the area of mains powered motor speed control using phase angle firing. Figure 9a demonstrates the principle of operation. In order to obtain a particular speed profile, the triac is fired symmetrically in positive and negative half cycles using pulses generated by the I.C. The waveforms show how the conduction angle is gradually advanced over a number of cycles to give smooth run up characteristics. A low cost solution giving minimal R.F.I. and well defined speedtime profiles is shown in Fig. 9b. The power supply and all timing and control pulses are derived directly from the A.C. mains. Each combination of the input switches defines a unique speed profile, and the gate switch controls and length of time spent at a given speed. Various fail safe features are included such as over current, over temperature, tachometer open circuit and prescribed shut down and run up characteristics.
387
Vehicle Weighing System Figure 10 shows a greatly simplified block schematic of a custom designed vehicle weighing system [6]. It is essentially an autoranging D.V.M. with additional high performance analogue and digital processing. A brief description of operation follows: The amplified output from four temperature compensated strain gauges mounted in the vehicle suspension system are operated on in the analogue processor. The output from the 12-Bit Digital to Analogue Converter, (D.A.C.) tracks this processed analogue voltage and the resulting binary number decoded to give a continuous digital display of the vehicles total axle weight on a small instrument mounted in the dashboard panel. Various facilities are provided such as automatic zeroing, which takes account of inclined and uneven surfaces; individual selection of each channel which enables the weight distribution to be checked; pre-settable alarms which give an external indication of the load status, which helps ensure that the vehicle is not overloaded without requiring the driver to keep checking the actual weight as shown on the cabin display. REFERENCES
1. D. L. Grundy, J. Bruchez and B. Down. Collector diffusion isolation packs many functions on a chip, Electronics, Jul. 1972. 2. C.D.I. A new bipolar process for integrated circuits, Ferranti Publication ESB 571072. 3. Lecture papers, Ferranti Electronics Exhibition and Symposium, 1973. 4. The uncommitted logic array, a C.D.I. standard product, Ferranti Publication ESB 620274. 5. C. Lewis, Custom L.S.I. for the small volume project, Electron, Feb. 1973.
CDI, THE BIPOLAR LSI T E C H N O L O G Y WITH TOTAL SYSTEMS I N T E G R A T I O N CAPABILITY P. KaEBS The system designer of today is becoming bewildered by an ever increasing variety of semiconductor technologies (if he can get passed identifying the initials). Among bipolar technologies, isoplanar and its variants, thin epitaxy processes such as Plessey Process 3, and integrated injection logic (I2L) all aim at specific types of advantage and are normally thus limited to specific market sectors. Metal oxide semiconductor (MOS) technologies have similarly proliferated, and can conveniently be split into single channel, e.g. P-Channel, and complementary MOS technologies. These again have their specific advantages and market sectors. Ferranti CDI, however, is unique in being able to penetrate a broad market front using a single and well understood standard process. Such an approach to a variety of systems is termed Total Systems Integration, which means that frequently a complete and relatively complex system can be realised on a single chip with minimal external components. This is made possible by the many attributes of CDI, such as the performance of a bipolar process with the packing density of MOS, the combination of digital and linear circuits on the same chip (digilin), excellent device performance over a wide current range and particularly at very low currents and good speed performance with better speed power product. To substantiate these claims, some examples of CDI products and applications are given below.
Universal Four Digit Display Counter This easy to use 5 V compatible display counter contains a host of features, such as automatic zero suppression, 50 mA segment drives, 8 MHz typical count rate etc. This enables users to provide digital readout on their equipment very simply.
Linear Processor This contains three high performance amplifiers and a shunt regulator, with communications and instrumentation applications.
Machine Tool Control This application of the display counter uses a low cost optical encoder to achieve digital position measurement at a cost at which almost any lathe could use it.
Temperature Control The combination of two linear processors with the display counter provides a powerful temperature control system with digital readout of temperature. M R - - V o l . 14, No. 4 - - E
385
Vehicle Weighing System A two chip system gives dashboard display of individual axle weight and total weight, ensuring balanced loading. This paper is divided into two sections, an outline comparison of CDI [1, 2-1 and other bipolar and MOS technologies, and application examples of CDI in action. Figure 1 shows a comparison table of CDI and other representative bipolar technologies. Points to pick out are that I2L is normally grafted on to another process, so that part of the processing advantage is lost; isoplanar and related processes need tight control of both epitaxial thickness and etching, where CDI only requires good epitaxy; and the apparent disadvantage of low voltage with CDI is frequently more than offset by the ability to include a voltage regulator in a (small) part of the I.C., allowing the use of dropper resistors for deriving power. A further interesting point concerns low power logic, which relies on the low current device performance to achieve low DC currents, again favouring CDI, e.g. for watches. Figure 2 shows a similar "star chart" comparison of CDI with established P-Channel MOS and with complementary MOS. A general point, concerning bipolar vs. MOS, is that the IC realisation is conceptually far more similar to a discrete version using bipolar ICs, giving potential users more confidence. Furthermore, bipolar circuitry is far more extensive and flexible than MOS. For CDI this is particularly true, as both digital and linear circuits can be processed simultaneously with the same (non-gold) CDI process by using a feedback emitter technique. Merely by a geometry change this reduces the transistor turn-off time out of saturation from tens of nonoseconds to under 8 nS. Another useful feature of bipolar vs. MOS is the drive capability, as bipolar drives of over 100 m_A allow direct interfacing with power devices such as thyristors or relays. In addition, the functional packing density of CDI is similar to that of P-Channel MOS, and better than CMOS. These comparisons add up to the fact that CDI offers a bipolar process with all the attendant advantages including digilin [3] with the packing density of MOS. This makes for a system approach of total system capability, whereby virtually all of the system (linear, digital, low power, drive, optoelectronic, etc.) can be included on chip, often within a single I.C., with minimal external components. This is achievable with a single standard process, whose other attributes are simplicity, high reliability, and very good device performance, particularly at low currents.
386
P. KREBS SYSTEM DIAGRAM
ov o _Enable
Blanking o
Digit select outputs
Lamp test
7 segment drives
B.CD outputs
Carry output
'ltl .l,lllllll
Decimal o point Digit select sense 0
ION L O G I C ~
l
Clock frequencyO external override Transfe~
Clear o Count inhibit o Count input 0 Count up/down o
Enable
Y
GATING
Reset
Fig. 4. Block diagram of ZN1040 universal four digit display counter. This combination as used in a typical system is shown in Fig. 3. Frequently a regulator is included on chip, and inputs, which include timing components, may be digital and linear. Chip processing is also digilin, and outputs may include high drive direct interfacing to power handling devices. Display Counter Turning to more concrete applications, Fig. 4 shows the block diagram of a universal 4 digit display counter, the ZN1040E. Major features include: 4 decades of up/down synchronous counting with support latching. High current (50 mA) segment outputs, and separate B.C.D. outputs. Look ahead carry, allowing count extension by direct connection. Self scanning (true or complement) system with internal oscillator which can be synchronised. Automatic zero suppression, also catering for decimal point. Blanking, lamp test, switch-on reset. 5 V compatible system for supplies, inputs and outputs. Linear Processor Figure 5 shows the ZN417, a linear processor containing three operational amplifiers and a shunt regulator. Typical parameters are as follows: Regulator: slope impedance 1-5 fl; regulated voltage 5.3 V nominal; temperature coefficient _ 100 ppm/°C. Amplifier: Unity gain bandwidth 74 dB at 590 MHz or 94 dB at 5 MHz; input current 10 nA; input offset 2 mV.
Used as comparator: Delay 100msec; rise time 20 nsec; fall time 40 nsec. Applications of the ZN417 include communications, instrumentation and stereo preamps. U.L.A. [4, 5] Another aspect of CDI is the cellular approach offered by the U.L.A. [4]. (Uncommitted Logic Array), enabling custom L.S.I. to be made quickly and cheaply by changing only the interconnection mask. An example of the U.L.A., which enjoys wide success in a variety of applications including digilin, is the ZNA103 TV syn. pulse generator, shown in Fig. 6. Machine Tool Control Turning to more general application areas of these products, Fig. 7 shows the block schematic of a machine tool measuring system (one axis). This uses the Ferranti 24 R1-529 250 low cost optical incremental encoder, in combination with the ZN1040E. The basic system permits measurements to (~001" increments of slide movement. The resolution and speed of operation is essentially limited by the mechanics of the system as the ZN1040E can be cascaded and can handle pulse rates up to 12 MHz, equivalent to 12,000 encoder revs/sec. Temperature Controller Figure 8 shows how the ZN1040E and ZN417 may be combined to make up a temperature control system giving continuous digital indication of oven temperature. The output of the thermistor/potentiometer network--varies linearly with temperature--controls a
CDI, the Bipolar LSI Technology with Total Systems Integration Capability voltage controlled oscillator, (A1, A2, A3), whose output frequency is calibrated to the temperature, and a comparator A4 which controls the gating of the output of the zero crossing detector A5 and hence the currcut supplied to the heater. A6 is connected to form a precise three second oscillator having a defined narrow pulse width. This pulse is used to transfer and hold the digitised reading and to reset the counter. The digitised display is thus updated every three seconds. Five user adjustments are provided. Two match the slope of the thermistor network curve to the frequency voltage slope of the V.C.O., the third is used to centre the dynamic range of the V.C.O.; the fourth is used to balance the system whilst the fifth is the normal input demand potentiometer.
Motor Speed Control Another application of the C.D.I. is in the area of mains powered motor speed control using phase angle firing. Figure 9a demonstrates the principle of operation. In order to obtain a particular speed profile, the triac is fired symmetrically in positive and negative half cycles using pulses generated by the I.C. The waveforms show how the conduction angle is gradually advanced over a number of cycles to give smooth run up characteristics. A low cost solution giving minimal R.F.I. and well defined speedtime profiles is shown in Fig. 9b. The power supply and all timing and control pulses are derived directly from the A.C. mains. Each combination of the input switches defines a unique speed profile, and the gate switch controls and length of time spent at a given speed. Various fail safe features are included such as over current, over temperature, tachometer open circuit and prescribed shut down and run up characteristics.
387
Vehicle Weighing System Figure 10 shows a greatly simplified block schematic of a custom designed vehicle weighing system [6]. It is essentially an autoranging D.V.M. with additional high performance analogue and digital processing. A brief description of operation follows: The amplified output from four temperature compensated strain gauges mounted in the vehicle suspension system are operated on in the analogue processor. The output from the 12-Bit Digital to Analogue Converter, (D.A.C.) tracks this processed analogue voltage and the resulting binary number decoded to give a continuous digital display of the vehicles total axle weight on a small instrument mounted in the dashboard panel. Various facilities are provided such as automatic zeroing, which takes account of inclined and uneven surfaces; individual selection of each channel which enables the weight distribution to be checked; pre-settable alarms which give an external indication of the load status, which helps ensure that the vehicle is not overloaded without requiring the driver to keep checking the actual weight as shown on the cabin display. REFERENCES
1. D. L. Grundy, J. Bruchez and B. Down. Collector diffusion isolation packs many functions on a chip, Electronics, Jul. 1972. 2. C.D.I. A new bipolar process for integrated circuits, Ferranti Publication ESB 571072. 3. Lecture papers, Ferranti Electronics Exhibition and Symposium, 1973. 4. The uncommitted logic array, a C.D.I. standard product, Ferranti Publication ESB 620274. 5. C. Lewis, Custom L.S.I. for the small volume project, Electron, Feb. 1973.