Large Signal GaAs MESFET Oscillator Design

Techniques for large signal GaAs MESFET oscillator design are described which do not require repeated large signal measurement. In the first technique, small signal S-parameter measurements are used with a computer program to compute the packaged and mounted device equivalent circuit. Large signal measurements are made to determine a mathematical relationship between only those parameters which vary under large signal conditions. These relationships are included in the computer program. Then, once the equivalent circuit has been computed from the small signal S-parameter measurements, those parameters varying under large signals are incrementally altered until large signal S parameters are obtained which correspond to maximum oscillator output power. These values are used to calculate embedding element values for six oscillator topologies. A coaxial cavity FET oscillator was built and tested using the large signal design theory, and it substantially verified the design technique. The second design technique is based on the fact that S/sub 21/ varied more than other S parameters under large signals. By making design calculations based on S/sub 21/ reduced to the point corresponding to maximum oscillator power, it was possible to get usable design information for an FET oscillator.     

Optically frequency modulated GaAs MESFET oscillator

A GaAs MESFET X-band oscillator has been frequency modulated by an amplitude modulated optical signal injected on the active device. A modulation index of 0.5 corresponding to MSK modulation has been achieved at 2 Mbit/s without parasitic amplitude modulation. It is shown that the FM modulation index variation against frequency is directly related to the drain current response of the FET considered as a photodetector. This responsivity has been measured to decrease above 5 MHz, which limits the oscillator FM capability.     

Analysis of Optically Controlled Microwave/Millimeter-Wave Device Structures

Light-induced voltage and the change in the source-to-drain channel current under optical illumination higher than the semiconductor band gap for GaAs MESFET, InP MESFET, Al/sub 0.3/Ga/sub 0.7/As/GaAs high electron mobility transistor (HEMT), and GaAs permeable base transistor (PBT) are analytically obtained. The GaAs PBT and GaAs MESFET have higher sensitivity than the InP MESFET. However, the Al/sub 0.3/Ga/sub 0.7/As/ GaAs HEMT is observed to have the highest sensitivity. Variations in the small-signal parameters, such as channel conductance, gate-to-source capacitance, and transconductance, as well as transient parameters, such as switching time and power-delay product, of GaAs MESFET with illumination are computed. The computed capacitance and transconductance are compared with the experimentally obtained values and are found to be in fair agreement. Based on these results, the design considerations for an optically controlled MESFET switch are discussed. Finally, variation in device parameter due to optical illumination and its effect on the cutoff frequencies f/sub T/ and f/sub max/ are also investigated.     

A Highly Stabilized GaAs FET Oscillator Using a Dielectric Resonator Feedback Circuit in 9-14 GHz

A new type of highly stabilized GaAs FET oscillator using a dielectric resonator and a stabilization resistor in the feedback circuit has been developed. The oscillator fabricated with a microwave integrated circuit has a high external quality factor Q/sub ex/ for more than1000 with no hysteresis phenomena. The microwave characteristics of the GaAs FET oscillator has revealed 1) high efficiency of 20 percent with 70-mW output power at 11.85 GHz, 2) a wide tuning range more than1000 MHz, 3) a wide oscillation frequency from 9 to 14 GHz with same MIC pattern by using five dielectric resonators of different sizes, 4) a high-frequency stability as low as /spl plusmn/ 150kHz in the tempature range from -20 to + 60/spl deg/ C, and 5) low FM noise of 0.07 Hz/ /spl radic/Hz at off-carrier frequency of 100kHz.     

Co-integration of GaAs MESFET and Si CMOS circuits

Co-integration of GaAs MESFET and Si CMOS circuits is demonstrated using GaAs-on-Si epitaxial growth on prefabricated Si wafers. This is thought to be the first report of circuit-level integration of the two types of devices in a coplanar structure. A 2-μm gate Si CMOS ring oscillator has shown a minimum delay of 570 ps/gate, whereas on the same wafer a 1-μm gate GaAs MESFET buffered-FET-logic (BFL) ring oscillator has a minimum delay of only 70 ps/gate. A composite ring oscillator consisting of Si CMOS invertors and GaAs MESFET invertors connected in a ring has been successfully fabricated     

GaAs Ultra-High-Speed Prescaler/Phase Frequency Comparator Using LSCFL (Short Paper)

A high-speed, low-power prescaler/phase frequency comparator (PFC) medium scale integration (MSI) circuit for a phase-locked stable oscillator is designed and fabricated using GaAs MESFET low-power source-coupled FET logic (LSCFL) circuitry. The construction of the 1/64 frequency divider prescaler/PFC is designed to obtain high-speed and low-power operation. The fabrication process used is buried p-layer SAINT with a 0.5-µm gate length. The fabricated prescaler/PFC MSI circuit, mounted on a newly developed high-frequency package, operates up to 7.6 GHz with a power dissipation of 730 mW.     

MIM gate FET: new GaAs enhancement-mode transistor

A new type of GaAs FET, the metal-insulator-metal gate FET, is proposed, which combines the advantages of both the GaAs MESFET and the GaAs MISFET. The device is especially suitable for the enhancement mode of operation.     

Pseudo-complementary FET logic (PCFL): a low-power logic family inGaAs

This paper describes an efficient low-power static logic family in GaAs, called PCFL for pseudo-complementary FET logic. Its behavior mimics that of CMOS by compensating the lack of complementary transistors with the use of complementary logic signals. Like any nonratioed logic, PCFL allows the realization of complex gates. It is fully compatible with DCFL and two-phase dynamic FET Logic (TDFL). Using enhancement-mode FET's only, PCFL benefits from good process variations immunity and good noise margins. Measurement results on a ring oscillator, an inverter chain, and a frequency divider are reported. PCFL is shown to operate at 500 MHz with a 0.6 μm MESFET process. The power consumption of an inverter is about 10 μW at 100 MHz     

Gigabit logic operation with enhancement-mode GaAs MESFET IC's

Enhancement-mode GaAs MESFET IC's have been fabricated using electron-beam lithography. A recessed-gate structure to reduce the gate-to-source resistance and an air-bridge overlay interconnect to reduce stray capacitance were employed. A 30-ps delay time with an associated power dissipation of 1.9 mW is obtained with a 0.6 × 20-µm gate GaAs MESFET, which is the highest speed among the GaAs FET logics. Divide-by-eight counter has exhibited a 3.8-GHz maximum clock frequency with a power dissipation of 1.2 mW/gate.     

An Efficient Approach for Large-Signal Modeling and Analysis of the GaAs MESFET

A nonlinear circuit model of the GaAs MESFET is developed by extracting circuit parameters from dc and small-signal RF measurements in a systematic manner. The circuit model is then analyzed by an efficient algorithm called the modified multiple-reflection method. For the first time, this method is applied to MESFET circuit analysis. Compared with the original multiple-reflection method, the modified multiple-reflection method shows a dramatic increase in convergence speed. The validity of the nonlinear MESFET model is confirmed by comparing the simulation results with experimental data.     

A novel FET model including an illumination intensity parameter forsimulation of optically controlled millimeter-wave oscillators

This paper demonstrates an illuminated FET model including an illumination-intensity parameter for simulation of optical characteristics of microwave and millimeter wave integrated circuits (MMIC's). Modeling for an illuminated GaAs MESFET and an InP high electron-mobility transistor (HEMT), and analysis and experimental results from optically controlled microwave and millimeter-wave hybrid integrated circuit (HIC) and MMIC oscillators are discussed. The proposed illuminated FET model was able to explain the photoresponse of both the GaAs MESFET and the InP HEMT, and the photooperation of their circuits     

A new low-noise FET structure

A novel monolithic FET topology has demonstrated improved minimum noise figure when compared with a conventional pi-gate FET. The structure, referred to as the spider FET, has allowed noise figures to be achieved in monolithic LNA applications that are 0.3 dB lower than in the standard 0.5-μm GaAs MESFET ion-implantation process. The improved spider FET performance is achieved by reducing the gate feed resistance and minimizing the parasitic gate-to-source capacitance in the region of the gate feed. The spider FET shows promise in 0.25-μm MESFET and HEMT (high electron mobility transistor) applications, as well as in power FET applications     

A Simplified Microwave Model of the GaAs Dual-Gate MESFET

A simplified wide-band model of the GaAs dual-gate MESFET based upon the familiar cascode representation is presented, which is valid over the frequency range of 2-11 GHz. The equivalent circuit contains 14 elements and the parameter values are directly determined from 3-port S-parameters over the frequency range of 4-6 GHz, and dc data. Separate microwave measurements of each FET part are not required, thus greatly reducing the number of measurements required to fully characterize the device. The method has been used to model a GaAs dual-gate MESFET in which both FET parts were in the saturation region, and good agreement has been obtained between measured and calculated results without the need for computer optimization.     

Development of a GaAs monolithic surface acoustic wave integratedcircuit

An oscillator technology using surface acoustic wave (SAW) delay lines integrated with GaAs MESFET electronics has been developed for GaAs-based integrated microsensor applications. The oscillator consists of a two-port SAW delay line in a feedback loop with a four-stage GaAs MESFET amplifier. Oscillators with frequencies of 470, 350, and 200 MHz have been designed and fabricated. This oscillator technology is most suitable for sensor applications but can logically be extended to radio-frequency oscillator and filter applications by methods well known for other piezoelectric substrates     

AlGaAs/GaAs MESFET IC with Ni buried gate technology

Ni buried gate technology for threshold voltage control using a Ni-GaAs reaction by a heat treatment is developed and successfully applied to AlGaAs/GaAs heterostructure MESFET IC's. Switching delay time of 36.7 ps with the power-delay product of 10 fJ (1-V supply voltage) was obtained at 83 K for a ring oscillator with 1.5-µm gate FET's. This technology, together with the saturated resistor loads, promises to simplify the process for AlGaAs/GaAs MESFET LSI's by not requiring active-layer etching.     

X波段变容管调谐GaAs FET集成VCO的设计

本文介绍了一种宽带FET VCO的S参数设计理论和方法.根据这一理论和方法,用我所的低噪声小功率FET和电调变容管,研制成了X波段变容营调谐的GaAs FBT混合集成VCO.在8GHz频段内,获得500MHz的电调范围,在整个电调范围内,输出功率大于10mW,功率起伏小于0.5dB,直流转换效率大于10%,噪声性能与普通速调管相当,而且体积小,重量轻,成本低.     

GaAsMMIC双栅MESFET混频器设计与实验研究

对微波单片集成 (简称 MMIC)双栅 MESFET混频器的设计理论和工艺技术进行较为细致的研究。根据双栅 MESFET的理论分析与实验结果 ,建立了一种栅压调制 I- V特性的经验模型 ,推导了双栅 FET混频器变频增益公式。分析了栅压对改变非线性跨导在混频器中的作用。最后设计并加工出了芯片面积为 0 .75 mm× 1 .5 mm Ga As MMIC双栅 FET混频器。     

2英寸GaAs快速热退火技术研究

为配合２０００门ＧａＡｓ超高速门阵列及ＧａＡｓ超高速分频器等２英寸ＧａＡｓ工艺技术研究，开展了２英寸ＧａＡｓ快速热退火技术研究。做出了阈值电压为０～０．２Ｖ，跨导大于１００ｍＳ／ｍｍ的Ｅ型ＧａＡｓＭＥＳＦＥＴ和夹断电压为－０．４～－０．６Ｖ，跨导大于１００ｍＳ／ｍｍ的低阈值Ｄ型ＧａＡｓＭＥＳＦＥＴ。     

Design and Performance of X-Band Oscillators with GaAs Schottky-Gate Field-Effect Transistors

The circuit construction and design of an X-band oscillator with a GaAs Schottky-gate FET have been studied. The oscillation characteristics including stability and noise performance have been examined in order to clarify the position of a GaAs FET as a microwave solid-state oscillator device. The experiments have revealed that 1) the GaAs FET simultaneously possesses the most desirable features of both Gunn and IMPATT oscillators, i.e., low bias voltage operation and fairly high efficiency, and 2) it is situated between Gunn and GaAs IMPATT oscillators with respect to noise properties. The results indicate that the GaAs FET oscillator will soon be joining the family of microwave solid-state oscillators as a promising new member.     

GaAs MESFET ring oscillator on Si substrate

GaAs MESFET ring oscillators were fabricated on a Si substrate and successfully operated. Epitaxial techniques to grow a GaAs layer on a Si substrate were investigated. The device-quality GaAs epitaxial layer was obtained by introducing a Ge layer (by ionized cluster-beam deposition) and alternating GaAs/GaAIAs layers (by MOCVD). The typical transconductance of 140 mS/mm was obtained for the FET with a 0.5 µm × 10 µm gate. The minimum delay time was 66.5 ps/ gate at a power consumption of 2.3 mW/gate.