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The electrical engineering handbook
Bahl, I.J. “Solid State Circuits” The Electrical Engineering Handbook Ed. Richard C. Dorf Boca Raton: CRC Press LLC, 2000 © 2000 by CRC Press LLC 43 Solid State Circuits 43.1Introduction 43.2Amplifiers 43.3Oscillators 43.4Multipliers 43.5Mixers 43.6Control Circuits 43.7Summary and Future Trends 43.1 Introduction Over the past two decades, microwave active circuits have evolved from individual solid state transistors and passive elements housed in conventional waveguides and/or coaxial lines to fully integrated planar assemblies, including active and passive components and interconnections, generically referred to as a microwave integrated circuit (MIC). The hybrid microwave integrated circuit (HMIC) consists of an interconnect pattern and distributed circuit components printed on a suitable substrate, with active and lumped circuit components (in packaged or chip form) attached individually to the printed interconnect circuit by the use of soldering and wire bonding techniques. The solid state active elements are either silicon or gallium arsenide (or other III–V compound) devices. More recently, the solid state monolithic microwave integrated circuit (MMIC) approach has become commonplace. In MMICs, all interconnections and components, both active and passive, are fabricated simultaneously on a semi-insulating semiconductor substrate (usually gallium arsenide, GaAs) using deposition and etching processes, thereby eliminating discrete components and wire bond interconnects. The term MMIC is used for circuits operating in the millimeter wave (30–300 GHz) region of the frequency spectrum as well as the microwave (1–30 GHz) region. Major advantages of MMICs include low cost, small size, low weight, circuit design flexibility, broadband performance, elimination of circuit tweaking, high-volume man- ufacturing capability, package simplification, improved reproducibility, improved reliability, and multifunction performance on a single chip. Microwave circuits use two types of active devices: two-terminal devices, referred to as diodes, such as Schottky, Gunn, tunnel, impact avalanche and transit time (IMPATT), varactor, and PIN , and three-terminal devices, referred to as transistors, such as bipolar junction transistor (BJT), metal semiconductor field effect transistor (MESFET), high electron mobility transistor (HEMT), heterostructure FET (HFET), and heterojunc- tion bipolar transistor (HBT). Microwave circuits using these devices include amplifiers , oscillators , multipli- ers , mixers , switches , phase shifters , attenuators , modulators, and many others used for receiver or transmitter applications covering microwave and millimeter wave frequency bands. New devices, microwave computer- aided design (CAD) tools, and automated testing have played a significant role in the advancement of these circuits during the past decade. The theory and performance of most of these circuits have been well documented [Kollberg, 1984; Bhartia and Bahl, 1984; Pucel, 1985; Maas, 1986; Bahl and Bhartia, 1988; Goyal, 1989; Ali et al., 1989; Chang, 1990; Vendelin et al., 1990; Ali and Gupta, 1991; Chang, 1994]. Solid state circuits are extensively used in such applications as radar, communication, navigation, electronic warfare (EW), smart weapons, I. J. Bahl ITT Gallium Arsenide Technology Center © 2000 by CRC Press LLC consumer electronics, and microwave instruments and equipment. This section will briefly describe the per- formance status of amplifiers, oscillators, multipliers, mixers, and microwave control circuits. 43.2 Amplifiers Amplifier circuits have received maximum attention in solid state circuits development. The two-terminal device amplifiers, such as parametric, tunnel, Gunn, and IMPATT, are normally called reflection-type circuits, or negative resistance amplifiers. A diagram for these amplifiers is shown in Fig. 43.1(a). Parametric amplifiers are narrow- band (<10%) and have very good noise figure. Tunnel-diode amplifiers are high-gain, low-noise figure, and low-power circuits. Octave bandwidth of such amplifiers is possible. The performance of Gunn-diode amplifiers is quite similar to tunnel-diode amplifiers. IMPATT-diode amplifiers are high power and high efficiency. They are moderately noisy, and bandwidths up to an octave are possible. The basic circuit configuration for three-terminal device amplifiers is shown in Fig. 43.1(b). Several different types of amplifiers developed using transistors are low noise, power, high linearity, broadband, high efficiency, logarithmic, limiting, transimpedance, and variable gain. The silicon bipolar transistor performs very well up to about 4 GHz, with reliable performance, high power, high gain, and low cost. The GaAs MESFETs perform better than the bipolar transistors above 4 GHz. They are broadband, have a wide dynamic range, are highly reliable, and are low cost. Both low-noise and medium-power MESFET amplifiers are available. They compete with uncooled parametric amplifiers as well as moderate-power IMPATTs. HEMTs find a niche in low-noise and high-frequency applications. The noise figure of HEMT amplifiers is better than that of uncooled para- metric amplifiers up to 100 GHz, as shown in Fig. 43.2. Various techniques are used to realize small signal or low-power broadband amplifiers. Five of them are shown in Fig. 43.3. The distributed approach provides the unique capability of excellent gain-bandwidth product, low VSWR (voltage standing wave ratio) , and moderately low noise figure. This technique has been successfully used in monolithic ultrabroadband amplifiers. The performance of such amplifiers using various transistor devices is given in Table 43.1. The performance of solid state power amplifiers is shown in Fig. 43.4. Currently, IMPATT and Gunn diodes provide maximum power above 10 GHz, whereas bipolar junction transistor and MESFET technologies offer the most promise to generate higher power levels below 10 GHz. In particular, IMPATT devices have been operated over the complete millimeter wave band and have shown good continuous wave (CW) and pulsed power efficiency and reliability. During the past decade significant progress has been made in monolithic power amplifiers operating over both the narrowband and broadband [Williams and Bahl, 1992; Tserng and Saunier, 1991]. Power levels as high as 12 W from a single MMIC chip at C-band with 60% power-added efficiency (PAE) have been demon- strated. A 6-W MMIC chip has been developed at X-band. A 2-W power output has been obtained at 30 GHz. FIGURE 43.1 Amplifier circuits configurations. (a) Two-terminal negative resistance type requires a circulator to isolate the input and output ports. (b) Three-terminal transistor type requires input and output matching networks. © 2000 by CRC Press LLC In the high- efficiency area, a C-band MMIC amplifier with 70% PAE, 8-dB gain, and 1.7-W power output has been demonstrated. For broadband amplifiers having an octave or more bandwidth, MMIC technology has been exclusively used and is quite promising. Figure 43.5 depicts power performance for single-chip MMIC amplifiers spanning microwave and millimeter wave frequencies. The state of the art in high efficiency and broadband power MMIC amplifiers is summarized in Tables 43.2 and 43.3, respectively. Note that the high- efficiency examples included in Table 43.2 all exceed 40% PAE. 43.3 Oscillators Solid state oscillators represent the basic microwave energy source and have the advantages of light weight and small size compared with microwave tubes. As shown in Fig. 43.6, a typical microwave oscillator consists of a MESFET as an active device (a diode can also be used) and a passive frequency-determining resonant element, such as a microstrip, surface acoustic wave (SAW), cavity resonator, or dielectric resonator for fixed tuned oscillators and a varactor or a yttrium iron garnet (YIG) sphere for tunable oscillators. These oscillators have the capability of temperature stabilization and phase locking. Dielectric resonator oscillators provide stable operation from 1 to 100 GHz as fixed frequency sources. In addition to their good frequency stability, they are simple in design, have high efficiency, and are compatible with MMIC technology. Gunn and IMPATT oscillators provide higher power levels and cover microwave and millimeter wave bands. The transistor oscillators using MESFETs, HEMTS, and HBTs provide highly cost-effective, miniature, reliable, and low-noise sources for use up to the millimeter wave frequency range, while BJT oscillators reach only 20 GHz. Compared to a GaAs MESFET oscillator, a BJT or a HBT oscillator typically has 6 to 10 dB lower phase noise very close to the carrier. Figure 43.7 shows the performance of various solid state oscillators. Higher power levels for oscillators are obtained by connecting high-power amplifiers at the output of medium-power oscillators. 43.4 Multipliers Microwave frequency multipliers are used to generate microwave power at levels above those obtainable with fundamental frequency oscillators. Several different nonlinear phenomena can be used to achieve frequency FIGURE 43.2 Comparison of noise performance of various solid state amplifiers; the InP HEMT LNA, which is also compatible with MMIC technology, is a clear choice for receiver applications where cryogenic cooling is precluded. ( Source: D. Willems and I. Bahl, “ Advances in Monolithic Microwave and Millimeter Wave Integrated Circuits,” IEEE Int. Circuits and Systems Symp. Digest, pp. 783–786. © 1992 IEEE. With permission.) © 2000 by CRC Press LLC multiplication, e.g., nonlinear reactance in varactors and step-recovery diodes and nonlinear resistance in Schottky barrier diodes and three-terminal devices (BJT, MESFET, HEMT, HBT). Varactor multipliers offer the best frequency multiplier performance. Varactor multipliers (pulsed) have achieved power output in excess of 100 and 10 W at 4 and 10 GHz, respectively [Bahl and Bhartia, 1988]. Table 43.4 shows the best performance measured in the millimeter wave range and above. 43.5 Mixers Mixers convert (heterodyne) the input frequency to a new frequency, where filtering and/or gain is easier to implement, in contrast to detectors, which are used to provide an output signal that contains the amplitude or amplitude variation information of the input signal. A mixer is basically a multiplier, which requires two FIGURE 43.3 Broadband amplifier configurations. Balanced has low noise figure and better cascadability, feedback has small size, active match is more suitable for monolithic approach, and distributed is good for multioctave bandwidths. RF In RF Out Identical Amplifier Stages 90¡ Hybrids Matching Network Matching Network MN MN MN Balanced Feedback Active Match Resistive/ Reactive Match Distributed © 2000 by CRC Press LLC signals and uses any solid state device that exhibits nonlinear properties. Mixing is achieved by applying an RF and a high-power local oscillator signal to a nonlinear element, which can be a diode or a transistor. As illustrated in Fig. 43.8, there are many types of mixers: one diode (single ended), two diodes (balanced or antiparallel), four diodes (double balanced), and eight diodes (double-double balanced). Mixers can also be realized using the nonlinearities associated with transistors that provide conversion gain. The most commonly used mixer configuration in the microwave frequency band is the double-balanced mixer, which has better isolation between the ports and better spurious response. However, the single and balanced mixers place lower power requirements on the local oscillator and have lower conversion loss. Subharmonic mixing (where the local oscillator frequency is approximately half that needed in conventional mixers) has been extensively used at millimeter wave frequencies. This technique is quite useful when reliable stable local oscillators are either unavailable or prohibitively expensive at high frequencies. Figure 43.9 gives the performance of millimeter wave mixers. TABLE 43.1 Broadband Single-Chip Distributed MMIC Amplifier Performance Frequency Noise Range (GHz) Gain (dB) Figure (dB) Device Used 0.5–26.5 6 5.2 0.32 m m GaAs HEMT 0.5–50 6 — 0.32 m m GaAs HEMT 2–18 9 5.7 0.5 m m dual gate FET 2–20 9.5 3.5 0.2 m m GaAs HEMT 2–24 6 — 2 m m SABM GaAs HBT 5–40 9 4.0 0.25 m m GaAs HEMT 5–60 8 — 0.25 m m GaAs HEMT 5–100 5 — 0.1 m m InP HEMT 6–18 10.5 — 0.4 m m GaAs MESFET 9–70 3.5 7.0 0.2 m m GaAs PHEMT SABM, self-aligned base ohmic metal; PHEMT, pseudomorphic HEMT. Source: D. Willems and I. Bahl, “Advances in Monolithic Microwave and Millimeter Wave Integrated Circuits,” IEEE Int. Circuits and Systems Symp. Digest, pp. 783–786. © 1992 IEEE. With permission. FIGURE 43.4 Power performance of microwave power amplifiers. © 2000 by CRC Press LLC FIGURE 43.5 Performance status of single-chip power MMIC amplifiers using MESFET, HFET, HEMT, and HBT technologies. TABLE 43.2 Single-Chip High-Efficiency Power MMIC Performance Frequency No. of (GHz) Stages P O (W) PAE (%) Gain (dB) 5.2 1 12.0* 60 9 5.5 1 1.7 70 8 8.5 2 3.2 52 — 10.0 1 5.0 48 7 10.0 1 6.0 44 6 11.5 2 3.0 42 12 Source: D. Willems and I. Bahl, “Advances in Monolithic Microwave and Millimeter Wave Integrated Circuits,” IEEE Int. Circuits and Systems Symp. Digest, pp. 783–786. © 1992 IEEE. With permission. *W.L. Pribble and E.L. Griffin, “An ion-implanted 13W C-band MMIC with 60% peak power added efficiency,” IEEE 1996 Microwave and Millime- ter-Wave Monolithic Circuits Symposium Digest, pp. 25–28. © 2000 by CRC Press LLC TABLE 43.3 Single-Chip Broadband Power MMIC Performance Frequency No. of (GHz) Configuration Stages Gain (dB) P O (W) PAE(%) 1.5–9.0 Reactive match 2 5 0.5 14 2.0–8.0 Distributed 1 5 1.0 — 2.0–20.0 Distributed 1 4 0.8 15 3.5–8.0 Reactive match 2 10 2.0 20 6–17 Distributed/reactive 4 16 0.8 11 6–20 Distributed 1 11 0.25 — 7–10.5 Reactive match 2 12.5 3.0 35 7.7–12.2 Reactive match 2 8.0 3.0 14 12–16 Reactive match 3 18 1.8 18 14–33 Distributed 1 4 0.1 — Source: D. Willems and I. Bahl, “Advances in Monolithic Microwave and Mil- limeter Wave Integrated Circuits,” IEEE Int. Circuits and Systems Symp. Digest, pp. 783–786. © 1992 IEEE. With permission. FIGURE 43.6 Basic configuration of a dielectric resonator oscillator. The feedback element is used to make the active device unstable, the matching network allows transfer of maximum power to the load, and the dielectric resonator provides frequency stability. FIGURE 43.7 Maximum CW power obtained from solid state microwave oscillators. © 2000 by CRC Press LLC 43.6 Control Circuits Control components are widely used in communication, radar, EW, instrument, and other systems for con- trolling the signal flow or to adjust the phase and amplitude of the signal [Bahl and Bhartia, 1988; Chang, 1990; Sharma, 1989; Sokolov, 1991]. PIN diodes and MESFETs are extensively used in HMICs and MMICs, respec- tively, for microwave control circuits, such as switches, phase shifters, attenuators, and limiters. PIN diode circuits have low loss and can handle higher power levels than do MESFET components; conversely, the latter have great flexibility in the design of integrated subsystems, consume negligible power, and are low cost. Figure 43.10 shows various control configurations being developed using PIN and MESFET devices. Either device can be used in these circuits. The most commonly used configuration for microwave switches is the single-pole double throw (SPDT) as shown in Fig. 43.10(a), which requires a minimum of two switching devices (diodes or transistors). Table 43.5 provides typical performance for broadband SPDT switches developed using GaAs MESFET monolithic tech- nology. Table 43.5 also summarizes performance for phase shifters and attenuators, which are described briefly below. There are four main types of solid state digitally controlled phase shifters: switched line, reflection, loaded line, and low-pass/high-pass, as shown in Fig. 43.10(b). The switched-line and low-pass/high-pass configura- tions, which are most suitable for broadband applications and compact size, are not suitable for analog operation. Reflection and loaded-line phase shifters are inherently narrowband; however, the loaded-line small bit phase shifters, 22.5 degrees or less, can be designed to have up to an octave bandwidth. Phase shifters using the vector-modulator concept have also been developed in monolithic form. Voltage-controlled variable attenuators are important control elements and are widely used for automatic gain control circuits. They are indispensable for temperature compensation of gain variation in broadband TABLE 43.4 Summary of State-of-the-Art Performance for Millimeter Wave Frequency Multipliers Tunable Output Minimum Output Maximum Output Maximum Mount Operating Band Effic. Power Effic. Power Freq. Pump Power Type (GHz) (%) (mW) (%) (mW) (GHz) (mW) Notes a Doubler 180–120 9.5 18 14.0 26.6 188 and 105 190 2, 3, 9 180–120 10.7 16 15.5 23.2 100 150 1, 2, 3 180–120 10 7 16 11 104 70 1, 4, 3 100 — — 25 20 100 80 6, 4 110–170 10 8 15 12.0 120 80 1, 2, 3 140–150 10 8 22 17.6 145 80 1, 2, 3, 5 190–260 10 8 27 21.5 215 80 1, 2, 3 200 — — 19 18 200 150 6, 4 400 — — 8.5 10.44 300 5.1 1, 2, 3, 7 500–600 7 0.7 — — — 10 1, 2, 8 Tripler 85–115 4 1.2 8 2.4 106 28 1, 2, 8 96–120 1.8 1.8 8.2 8.2 110 100 1, 2, 3 105 — — 25 18 105 72 6, 4 200–290 2.5 2.0 7.5 6 225 80 1, 2, 3 190–240 1 0.3 10 3 230 30 1, 2, 8 260–350 1.8 1.5 3.75 3.0 340 80 2, 3, 6 300 — — 2 2 300 100 6, 4 450 — — 1 0.079 450 6.3 1, 2, 3, 7 ´ 6 balanced 310–350 0.3 0.6 0.4 0.75 345 190 1, 2, 3, 6, 9 doubler/tripler a 1, Crossed waveguide mount; 2, tuning and bias optimized at each operating frequency; 3, microstrip low-pass filter; 4, fixed tuning and bias; 5, narrowbanded version of NRAO 110- to 170-GHz doubler; 6, quasi-optical mount; 7, limited pump power available; 8, coaxial low-pass filter; 9, two-diode balanced cross guide mounts. © 2000 by CRC Press LLC FIGURE 43.8 Basic mixer configurations: (a) single ended, (b) balanced, (c) double balanced, and (d) double-double balanced. FIGURE 43.9 Single-sideband (SSB) conversion loss of millimeter wave mixers. Subharmonic type mixers have higher conversion loss but are generally less expensive. 2.0 20 60 100 140 180 220 260 4.0 6.0 8.0 10.0 Subharmonic Mixer RF FREQUENCY (GHz) SSB CONVERSION LOSS (db) Fundamental Mixer . played a significant role in the advancement of these circuits during the past decade. The theory and performance of most of these circuits have been well. oscillator. The feedback element is used to make the active device unstable, the matching network allows transfer of maximum power to the load, and the dielectric