C.S. Chou

AlInAs/GaInAs on InP HEMT low noise MMIC amplifiers

AlInAs/GaInAs on InP HEMT (high electron mobility transistor) single-stage low-noise MMIC (monolithic microwave integrated circuit) amplifiers have been developed for operation at 12 GHz, 35 GHz and 60 GHz. A noise figure of 0.78 dB with an associated gain of 15 dB was achieved at 12 GHz. This is the lowest noise figure yet reported for a monolithic amplifier at 12 GHz. A noise figure of 1.2 dB with gain greater than 12 dB was obtained from 10 to 14 GHz. At 35.5 GHz, 13 dB gain with 17 dB input return loss was obtained. At 55 GHz, 8 dB gain with more than 12 dB input return loss was obtained.<<ETX>>

Low-temperature buffer AlInAs/GaInAs on InP HEMT technology for ultra-high-speed integrated circuits

A report is presented on the development of a planar low-temperature buffer AlInAs/GaInAs on InP high-electron-mobility transistor (HEMT) technology for use in digital and analog integrated circuits. This technology is attractive for circuit applications because of the high achievable f/sub T/ and f/sub max/, low output conductance and gate leakage current, and reduced susceptibility to backgating effects. Two alternative logic families-UFL and SCFL (source-couple FET logic)-were chosen for the realization of digital circuits. Measurements on the UFL ring oscillators exhibited a minimum gate delay of 13 ps with a power dissipation of 1.1 mW/gate at room temperature. The gate delay rose to 25 ps when the power dissipation increased to 3 mW/gate. This gate delay is expected to drop significantly with reductions in diode level-shift series resistance and improvements in transistor f/sub T/. The most complex SCFL circuit tested was a divide-by-eight counter. The SCFL circuits were configured as flip-flops in the divide-by-eight mode. The circuit operated at a maximum clock rate of 12.5 GHz.<<ETX>>

High-efficiency InP-based HEMT MMIC power amplifier for Q-band applications

Advanced millimeter-wave systems require high efficiency MMIC power amplifiers to reduce physical size, weight, and prime power consumption. A high-efficiency MMIC power amplifier was developed using 0.15 um InP-based (Al/sub 0.48/In/sub 0.52/As-Ga/sub 0.47/In/sub 0.53/As) HEMT MMIC technology. The amplifier demonstrated state-of-the-art power performance, including 33% power-added efficiency and 24 dBm output power at 44 GHz. Potential applications include communication terminals and phased array antennas.<<ETX>>

44-GHz high-efficiency InP-HEMT MMIC power amplifier

A high-efficiency power amplifier was developed using 0.15-/spl mu/m gatelength, InP-based (GaInAs/AlInAs/InP), HEMT MMIC technology. The amplifier demonstrated state-of-the-art performance. The output power at 1-dB compression point was 28 dBm at 44.5 GHz. The corresponding power-added efficiency was 31% and gain was 7 dB. The total chip area was 2.5 mm/sup 2/.<<ETX>>

High-efficiency InP-based HEMT MMIC power amplifier

High-efficiency monolithic Q-band power amplifiers were developed using InP based HEMT MMIC technology. The amplifiers demonstrated state-of-the-art power performance including 33% power-added efficiency and 26 dBm of output power at 44 GHz. This is the highest output power reported with such a high efficiency for InP-based HEMT MMIC power amplifiers at Q-bands. The intended application is communication terminals.<<ETX>>

Low temperature MBE growth of GaAs and AlInAs for high speed devices

Low-temperature GaAs buffer technology was used to fabricate high-performance 0.2- mu m-gate-length, spike-doped GaAs MESFETs. A 400.0-nm low-temperature GaAs buffer was grown by molecular beam epitaxy (MBE) at a substrate temperature of 300 degrees C. The substrate temperature was raised to 580 degrees C for a brief in situ anneal and followed by the growth of the active spike-doped GaAs MESFET structure. The peak extrinsic transconductance, g/sub m/, was 600 mS/mm with an average pinch-off voltage, V/sub po/, of -0.6 V. An output conductance, g/sub o/, of 24 mS/mm resulted in a voltage gain of 25. The extrapolated f/sub T/ of the devices was 79 GHz. Static SCFL (source-coupled FET logic) frequency dividers fabricated in this technology exhibit a maximum clock rate of 22 GHz. Low-temperature AlInAs buffer growth has been applied to GaInAs/AlInAs HEMT (high-electron-mobility transistor) devices on InP. A 250.0-nm AlInAs buffer was grown at a substrate temperature of 150 degrees C, followed by an anneal under arsenic overpressure and a GaInAs/AlInAs superlattice prior to the HEMT structure, which is grown at T=510 degrees C. Devices fabricated with 0.2- mu m gates had g/sub m/ of 670 mS/mm and g/sub o/ of 2.55 mS/mm, giving a voltage gain of 250.<<ETX>>

GaAs MESFET digital integrated circuits fabricated with low temperature buffer technology

High-performance digital integrated circuits have been fabricated with low-temperature buffer GaAs MESFET technology. The materials structure eliminates side-gating and light sensitivity, and improves FET performance. Individual transistors with a 0.2-μm gate length have a transconductance gm of 600 mS/mm and an extrapolated cutoff frequency fT of 80 GHz. Static SCFL frequency dividers fabricated in this technology exhibit a maximum clock rate of 22 GHz

Wideband impedance-matched integrated optoelectronic transmitter

ABSTRACT A GaAs/GaAlAsintegrated optoelectronic transmitterhas been developed for wideband operation at 1 to4 GHz. This transmittercombines a GaAS/GaA1AS single-quantum-well (SQW) ridge-waveguide laserwith a GaAs MESFET driver circuit The single-stage driver circuit has an rfgain of9 dB and is impedance matched to both the low resistance laserload and the 50 fl microwaveinput by using reactive MMIC components. This design results in a nearly flat frequency response in the band of interest Acombination of both laser and MMIC fabrication processes has been used to realize the transmitter in the vertically integratedMOVPE-grown material. 1. INTRODUCTION Monolithically integratedoptoelectronic transmittershavedemonstratedvery high speedoperauonandcanbeusedin microwave-modulatedopticallinks orhigh-speeddigital interconnects. Small-signal analog modulation frequencies of3 to6GHz and digitalmodulation rates as high as 10 Gb/s have been reported.15 By combining these transmitters with integrated receivers and optical

Multigigahertz monolithic GaAs optoelectronic receivers using 0.2 mu m gate-length MESFETs

Two GaAs optical receiver front-ends are reported. Each consists of an MSM photodetector and a transresistance amplifier that drives a 50 Omega load. One amplifier has a measured analog bandwidth of 6.5 GHz, while the other has one of 4.5 GHz. The transresistance-bandwidth product for both is 2.1 THz- Omega .<<ETX>>

GaAs/GaAlAs integrated optoelectronic transmitter for microwave applications

A monolithically integrated optoelectronic transmitter is being developed for wideband microwave-modulated links. The transmitter is designed to operate at signal frequencies of several gigahertz. It combines a GaAs/GaAlAs ridge-waveguide laser with a GaAs MESFET driver circuit. The laser has one of its cavity mirrors formed by dry etching so that the die size of the transmitter is not limited to the laser cavity length. The single-stage driver circuit is matched to both the low impedance of the laser and the 50 (Omega) microwave input by the inclusion of reactive components. A single-growth, vertically integrated material structure is used. Potential step-coverage problems that might result from this vertical integration are avoided by the use of air-bridge connections. The submicrometer FET gates are formed by direct-write electron-beam lithography.