This paper describes the design, fabrication, and performance of a C- to Ku-band 2 W balanced amplifier multi-chip module employing an MMIC/Super-MIC/MIC configuration. In this module, single-ended amplifiers, quadrature couplers, and pulsed-drive circuits are fabricated on MMICs, Super-MICs, and MICs, respectively, which show different features in fabrication, performance, size, and cost. With the use of the distinguished features of MMICs, Super-MICs, and MICs, the multi-chip module with high performance, small size, and low cost has been achieved. The MMIC/Super-MIC/MIC-combined module would be a candidate for a variety of multi-chip modules with stringent requirements for performance, size, and cost.

This paper describes the design, fabrication, and performance of a GaAs FET linearizer with a large source inductance, focusing mainly on (a) a mechanism of positive gain and negative phase deviations for input power, (b) stability considerations, and (c) a dependence on load impedance. In addition, in an application to the linearized amplifier, it is shown that an improvement can be achieved for adjacent channel leakage power (ACP) and third order intermodulation distortion (IM3) with the use of the linearizer.

A multi-terminal serial optical link(MSOL) achieves very simple and cost effective radio cell configurations because only one pair of fibers is needed. In addition, low cost Fabry-Perot laser diodes(FP-LDs) can be employed. MSOL has a substantial problem in that the beat noise degrades the C/N in the up-link. To reduce this noise, we propose using an automatic wavelength-offset control(AWOC) circuit. The AWOC circuit offsets the LD wavelength by controlling the laser bias current to minimise the RF band beat noise which is inherent in MSOL systems, and enables high C/N optical-microwave transmission. An experimental MSOL consisting of 5 radio access stations, each equipped with AWOC, is constructed to estimate the noise free dynamic range for 800-MHz 20-carrier signal transmission. The up-link comprises a single mode fiber connecting five 1.3-µm FP-LDs operating at 0.2 mW. The down-link consists of a single mode fiber and one 1.3-µm Distributed Feedback type Laser Diode(DFB-LD) emitting at 4.0 mW. The experimental device achieves over 15 dB noise reduction compared to MSOL without AWOC in the temperature range of 0 to 40. By using the proposed AWOC, MSOL can achive low cost optical fiber RF microcell systems that are easy to install. Additionally, when we install MSOL in the radio base station, the links become more cost effective than coaxial cable links; they offer a wide dynamic range and higher transmission quality.

Recent advances in 77-GHz MMIC module design techniques for automotive radar applications are reviewed in this paper. The target of R&D activities is moving from high performance to low cost, mass production, high-yield manufacturing and testing. To meet the stringent requirements, millimeter-wave module design techniques have made significant progress especially in packaging, bonding, and making interface with other modules. In addition, millimeter-wave semiconductor devices and MMICs have made remarkable improvements for low cost and mass production. In this paper, the topics focusing on millimeter-wave semiconductor devices and 77-GHz MMICs are reviewed first. Then the recent R&D results on 77-GHz MMIC module design techniques are introduced, showing the technical trend of packaging, bonding, and making interface with other modules for millimeter-wave, highly-integrated, low-cost MMIC modules. Finally, the existing and future module design issues for automotive radar applications are discussed.

Fundamental perspective of high power devices and amplifiers for use in wireless communication systems are described in this paper. First, high power devices and device modeling techniques are presented, focusing on the emerging device technologies such as wide bandgap devices (GaN, SiC) and SiGe devices. Then the commercially available device, circuit and system simulators for wireless communication applications are introduced. Recent active load-pull measurements have made a remarkable progress in fundamental, harmonic, and envelope frequencies for high efficiency and low distortion designs. In addition, pulsed DC/RF and on wafer load-pull measurements have also become popular, which are briefly reviewed. Finally the advances in high power amplifier design techniques for achieving high efficiency and low distortion are presented.

A 0.1 to 18 GHz hybrid distributed amplifier using GaAs HEMTs with 0.3 micron gate length and 200 micron gate width has been realized. This amplifier exhibits 9.00.5 dB of gain and less than 5.4 dB of noise figure. This letter describes the design approach which maximizes the gain-bandwidth product of the hybrid distributed amplifier, adding several FETs.

A novel nonlinear analysis method of high power amplifier instability has been developed. This analysis method deals with a loop oscillation in a closed loop circuit and presents the conditions for oscillation under large-signal operation by taking account of mixing effect of FETs. Applying this analysis to the high power amplifier instability that an output power for the fundamental wave (f0-wave) decreases at some compression point where a half of the fundamental wave (f0/2-wave) is observed, it has been found that this instability is caused by an f0/2 loop oscillation. In addition, it has been verified by analysis and experiment that the oscillation can be removed by employing an isolation resistor in a closed loop circuit.

L-band SiGe HBT frequency-tunable differential amplifiers with dual-bandpass or dual-bandstop responses have been developed for the next generation adaptive and/or reconfigurable wireless radios. Varactor-loaded dual-band resonators comprised of series and parallel LC circuits are employed in the output circuit of differential amplifiers for realizing dual-bandpass responses as well as the series feedback circuit for dual-bandstop responses. The varactor-loaded series and parallel LC resonator can provide a wider frequency separation between dual-band frequencies than the stacked LC resonator. With the use of the varactor-loaded dual-band resonator in the design of the low-noise SiGe HBT differential amplifier with dual-bandpass responses, the lower-band frequency can be varied from 0.58 to 0.77 GHz with a fixed upper-band frequency of 1.54 GHz. Meanwhile, the upper-band frequency can be varied from 1.1 to 1.5 GHz for a fixed lower-band frequency of 0.57 GHz. The dual-band gain was 6.4 to 13.3 dB over the whole frequency band. In addition, with the use of the varactor-loaded dual-band resonator in the design of the low-noise differential amplifier with dual-bandstop responses, the lower bandstop frequency can be varied from 0.38 to 0.68 GHz with an upper bandstop frequency from 1.05 to 1.12 GHz. Meanwhile, the upper bandstop frequency can be varied from 0.69 to 1.02 GHz for a lower bandstop frequency of 0.38 GHz. The maximal dual-band rejection of gain was 14.4 dB. The varactor-loaded dual-band resonator presented in this paper is expected to greatly contribute to realizing the next generation adaptive and/or reconfigurable wireless transceivers.

Recently, intelligent heating, next generation microwave ovens that achieve uniform heating and spot heating using solid-state devices, has been actively studied. There are two types of microwave generators using solid-state devices. Since compactness is indispensable to accommodate in a limited space, the miniaturized oscillator type was selected. The authors proposed an imbalanced coupling resonator, a resonator-less feedback circuit, a high power frequency variable resonator, and injection-locked phase control in order to achieve high performance of the oscillator type microwave generator. In addition, we confirmed that the oscillator type can be used as the microwave generator for intelligent heating using a Wilkinson combiner. As a result, it was demonstrated that the oscillator type microwave generator, realized the same high efficiency (67%) as the amplifier type, and found the possibility of variable frequency (2.4 to 2.5GHz) and variable phase, and can be used as the microwave generator for intelligent heating.

A wideband high power amplifier design using a novel band-pass filter with FET's parasitic reactances has been developed. The feature of this design is in that it can provide wide bandwidth and high gain of high power amplifiers. Furthermore, the lower cutoff frequency and bandwidth can be varied independently. With the use of this design, a Ku-band two-stage high power amplifier having a bandwidth of 18% has achieved a linear gain of 9.751.75 dB, a saturated output power of greater than 37 dBm, and a power-added efficiency of greater than 10.4%.

Miniaturized millimeter-wave HMIC amplifiers have been developed by using capacitively-coupled matching circuits (CCMC) and FETs with resistive source-stubs. CCMC includes FET's parasitic reactances, and is able to reduce the size of a matching circuit in a HMIC amplifier to about 1/3 of a conventional matching circuit using an open-circuited stub for matching and a quarter-wavelength coupled-line for d. c. blocking. The resistive source-stubs, which consist of two open-circuited stubs and a resistor, can improve the gain and stability of FETs at millimeter-wave frequencies. In this paper, design procedures of CCMC and the resistive source-stubs are described, and their usefulness has been confirmed experimentally through measurements of prototype V-band high-power HMIC amplifiers.

This paper describes a calculation method of large-signal characteristics of multi-stage power amplifier modules using source-pull and load-pull data. An output power, a power-added efficiency, and a phase deviation of multi-stage power amplifier modules are calculated based on the source-pull and load-pull data, which are comprised of input and output reflection coefficients, an input power, an output power, a phase deviation and a drain voltage and current, taking into account the source and load impedance of each stage FET. Applying this method to a 900 MHz two-stage Si-MOSFET power amplifier module, the calculated and measured results are in good agreement.

A novel compact T/R (Transmit/Receive) switching circuit for wideband T/R modules has been proposed. It employs quadrature couplers and gate-and-drain-driven HPAs to remove circulators or T/R switches from a conventional T/R module, and T/R switching is made with controlling biasing conditions of the FETs in HPAs. Furthermore, an optimum biasing condition and design of output matching circuit of the HPA have been studied to reduce loss in RX-mode, and the validity of the method has been confirmed by measurements.

Miniaturized opto and microwave receiver module using DCCPWs (Double Conductor Coplanar Waveguides) have been developed for active phased array antennas. The module comprised by a microstrip-to-slot transition, two chips of low-noise MMIC amplifiers, and a laser diode module is fabricated on an ultra-thin package with 10301.5 mm3 in size and 2 g in weight to achieve an ultra-thin structure of active phased array antenna panels. The ultra-thin structure is attributed to the design of low-noise MMIC amplifiers using DCCPWs and laser diode modules using silicon V-groove technology and fiber alignment method.

The paper presents the analysis, design and performance of PCB (Printed Circuit Board)-based cross-coupled differential VCOs using a novel LC-tank. As compared with the conventional LC-tank, a novel LC-tank is comprised of only chip inductors and thus has an advantage in providing a higher cutoff frequency. This feature attributes to the use of the parasitic elements of the chip inductors and capacitors. The cutoff frequencies were compared for both LC-tanks by calculation, simulation and measurement. Then the traditional cross-coupled differential oscillators having both LC-tanks were designed, fabricated and performed by using 0.35µm SiGe HBTs and 1005-type chip devices. The implemented oscillator using a novel LC-tank has shown a 0.12GHz higher oscillation frequency, while phase noise characteristics were almost the same. In addition, the cross-coupled differential oscillator utilizes a series RL circuit in order to suppress the concurrent oscillations. The implemented cross-coupled differential VCO employing Si varactor diodes with a capacitance ratio of 2.5 to 1 has achieved a tuning frequency of 0.92 to 1.28GHz, an output power greater than -13.5dBm, a consumed power less than 8.7mW and a phase noise at 100kHz offset in a range from -104 to -100dBc/Hz.

A 4-12 GHz 2 W GaAs HFET amplifier has been developed. It employs two novel circuit design techniques. One is a pre-matching circuit for dual gate-bias feed. It is comprised of two shunt LCR circuits, which makes dual gate-bias feed possible. The other one is a tapered power splitting/combining FET (tapered PS/PC FET), which makes amplitude and phase imbalance between FET cells small over a wide bandwidth. In this paper, the schematic diagram and impedance characteristic of the pre-matching circuit for dual gate-bias feed are described first, showing the conditions that the impedance of FETs becomes purely resistive. Then the amplitude and phase imbalance between FET cells are compared by electromagnetic simulation for both the conventional and tapered PS/PC FETs, demonstrating that the tapered PS/PC FET has smaller amplitude and phase imbalance. Furthermore, the MSG/MAG are compared by experiment for both FETs, confirming that the tapered PS/PC FET has higher MSG/MAG. Finally, the design, fabrication, and performance of the 4-12 GHz 2 W GaAs HFET amplifier using the pre-matching circuit for dual gate-bias feed and tapered PS/PC FETs are presented to make sure that two novel circuit design techniques introduced in this paper are useful for the design of wideband lossy match power amplifiers.

A direct calculation method of efficiency and power of FETs from d.c. characteristics determined by knee and breakdown voltages is proposed to make clear the requirements for knee and breakdown voltages of FETs under low-voltage operation of power amplifiers. It is shown from the calculation that the breakdown voltage has a greater effect on power and efficiency than the knee voltage and has to be three or more times of the operating voltage in order not to degrade efficiency under class-AB operation. A 3.3 V UHF-band 3-stage high efficiency and high power monolithic amplifier has been developed with the use of power FETs satisfying the requirements for knee and breakdown voltages under low-voltage operation. A power-added efficiency of 57.3% and a saturated output power of 31.8 dBm have been achieved for a drain voltage of 3.3 V in UHF-band. The direct calculation method of efficiency and power from d.c. characteristics, which can provide the required knee or breakdown voltage for a given efficiency, power, or bias conditions, is considered to be useful for developing power devices with various requirements for efficiency, power, and bias conditions.

Millimeter-wave monolithic low noise amplifier modules using 0.15 µm AlGaAs/InGaAs/GaAs pseudomorphic HEMTs have been developed at V- and W-bands for the Advanced Microwave Scanning Radiometer. To achieve low noise and high gain of V-band single-stage and W-band two-stage monolithic amplifiers, a reactive matching method is employed in the design of input noise matching and output gain matching circuits based on the results of on-carrier S-parameter measurements up to 50 GHz and noise parameter measurements at 60 and 90 GHz. A V-band four-stage monolithic amplifier module has been mounted on a hermetically-sealed package with microstrip interface and has achieved a noise figure of 3 dB with a gain of 42.2 dB at 51 GHz. A W-band six-stage amplifier module has been mounted on a hermetically-sealed package with waveguide interface and has achieved a noise figure of 4.3 dB with a gain of 28.1 dB at 91 GHz. These results represent the best noise figure performance ever achieved by multi-stage monolithic low-noise amplifier modules.

Recent advances in measurement techniques for microwave active devices and circuits are reviewed in this paper. The R&D activities have been devoted aggressively how to characterize nonlinear performance of high power devices and circuits. They are pulsed I-V, a variety of load-pull measurements, probing, sampling, and sensing techniques, supported by the recent significant advances in DSP (Digital Signal Processing), RF components, semiconductor devices, etc. The recent advances in vector network analyzers are of our great interest. They are (a) multi-port vector network analyzers for characterizing mixers, differential devices, packaged components, electronic package characterization, and multi-layer transmission lines, and (b) EO (Electro-Optic) modulated vector network analyzers for characterizing electronic performance of EO devices with the aid of EO modulators and photonic probes. In addition, probing, sampling, and sensing techniques have made great progress to directly measure electromagnetic field, time-domain voltage waveform, and temperature in small spot areas. In this paper, some topics related to these measurement techniques are briefly reviewed. Then the existing and future issues for characterization and measurement techniques of microwave active devices and circuits are discussed.