W.J. Ho

Application of GaInP/GaAs DHBTs to power amplifiers for wireless communications

Next-generation power amplifiers must operate at lower supply voltages without sacrificing linearity or efficiency. GaInP/GaAs double-heterojunction bipolar transistors with GaInP collectors can improve over GaAs single-heterojunction bipolar transistors (HBTs) in power-amplifier applications, based on lower offset voltage, increased breakdown electric field, and absence of saturation charge storage. To best exploit these characteristics, amplifier architectures that employ HBTs in switching mode can be used.

A 30 GHz bandwidth AlGaAs-GaAs HBT direct-coupled feedback amplifier

A DC to 30 GHz broadband amplifier based on the Darlington connected transistors with series and shunt resistive feedback was implemented with self-aligned AlGaAs-GaAs heterojunction bipolar transistor (HBT) technology. The measured performance shows 7.8 dB of gain with -3-dB roll-off bandwidth of 30 GHz. Measured at 1 GHz, the noise figure was 5.7 dB, 1-dB compression power was 11 dBm, and the third-order intermodulation product intercept point (IP3) was 23.9 dBm.<<ETX>>

High-performance low-base-collector capacitance AlGaAs/GaAs heterojunction bipolar transistors fabricated by deep ion implantation

Low-base-collector capacitance (C/sub bc/) AlGaAs/GaAs HBTs with f/sub MAX/>200 GHz and f/sub T/=52 GHz have been fabricated. With co-implants of high energy, high dose He/sup +/ and H/sup +/ ions through the external base layer, part of the heavily doped n/sup +/ sub-collector was compensated leading to a decrease in the extrinsic portion of C/sub bc/. The implants caused only a slight increase of base resistance. Using this approach in combination with a standard low dose, shallow collector compensating implant, C/sub bc/ of double implanted HBTs can be reduced by more than 35%.<<ETX>>

4 W, 7-12 GHz, compact CB HBT MMIC power amplifier

Extremely compact, broadband, heterojunction bipolar transistor (HBT) power amplifiers (PAs) were demonstrated with excellent performance. Common base (CB) HBTs were used in three single-stage broadband power amplifier designs, 1 W, 2 W, and 4 W, covering 7 to 11 GHz. In addition, a 1-W common emitter (CE) HBT linear amplifier was studied for its intermodulation property for communication application. The CB HBT PAs show good scaling relation in output power level. The peak power added efficiency is 40% for both the 1-W and 2-W versions, and 34% for the 4-W version. The chip size is only 2.15 mm by 2.9 mm for the 4-W CB HBT power amplifier. The CE HBT PA provides 1-W saturated output power in class B operation. In class A linear operation, 0.4-W output power was achieved. A two-tone test showed that IM/sub 3/ is better than -20 dBc at 1-dB compression point.<<ETX>>

A high-efficiency HBT MMIC power amplifier

An AlGaAs/GaAs heterojunction bipolar transistor monolithic microwave IC (HBT MMIC) power amplifier is developed that demonstrates very high power-added efficiency, high gain, and broad bandwidth. It uses a cascode structure with four 200- mu m common-emitter HBT cells driving four common-base cells of the same size. This amplifier achieves over 14-dB gain from 6 to 10 GHz, with a peak power-added efficiency (PAE) of 47% at 7.5 GHz at an output power level of 31 dBm. This corresponds to a power density of over 3 W per millimeter of emitter length. Input and output matching networks, as well as biasing networks, are all contained within the chip, which measures 80*80 mils (2*2 mm).<<ETX>>

0.7 W X-Ku-band high-gain, high-efficiency common base power HBT

Small sized AlGaAs-GaAs HBTs (heterojunction bipolar transistors) have achieved excellent power performance throughout the microwave frequency band. With the implementation of the multi-via-hole design, the HBT performance (gain and efficiency) is maintained as the size increases. A 0.7 W common-base (CB) power HBT with performance around 10 dB gain and 50% PAE well into the Ku band is reported. The performance is comparable to the pseudomorphic HEMT in this frequency range. The yield and uniformity are excellent. The high bias voltage (9.3 V V/sub ce/) is also desirable from a system viewpoint. >

44-GHz monolithic plane-wave amplifiers

A Plane Wave Amplifier is an array of small power amplifiers that accept input signals via input antennas and radiate amplified output signals from an output antenna. Such array amplifiers promise a method of efficient power at EHF. This concept has been experimentally explored in the 40-50 GHz band and gain over acceptable bandwidths has been measured. >

A GaAs BiFET LSI technology

A GaAs BiFET LSI technology has been successfully developed for low power, mixed mode communication circuit applications. The direct placement of the FET on the HBT emitter cap layer simplifies the device epitaxial growth and process integration. High integration levels and functional circuit yield have been achieved. Excellent HBT and FET characteristics have been produced with the noise figure of the FETs comparable to those of traditional MESFETs, enabling them to perform well in front end receiver applications. Through this technology, several LSI circuits, including 32-bit by 2-bit shift registers and a single-chip DRFM have been successfully demonstrated.

25 GHz HBT frequency dividers

A report is presented on a regenerative frequency divider and a static frequency divider implemented with (AlGa)As/GaAs heterojunction bipolar transistors (HBTs). Both dividers have been operated at input frequencies higher than 25 GHz. Also described is a frequency divider implemented with AlInAs/GaInAs HBTs operating up to 17.1 GHz, at considerably reduced power. These frequency dividers are among the fastest ever reported for each of these circuit types and illustrate the feasibility of using direct frequency division in microwave systems up to K/sub u/ band.<<ETX>>

A multifunctional HBT technology

A self-aligned AlGaAs/GaAs HBT technology has been developed for the fabrication of both high-performance microwave circuits and high-performance digital circuits. The technology provides transistors with high f/sub max/ (up to 218 GHz), high f/sub t/ (up to 98 GHz), and high efficiency (power added efficiency higher than 67.8% at 10 GHz) microwave amplification to at least 20 GHz. A MMIC amplifier has demonstrated 7-dB gain between 14 and 24 GHz. Excellent performance of high-speed digital circuits, such as ring oscillators, frequency dividers, MUXs, DEMUXs, and phase detectors has also been achieved on the same wafer. A multifunction chip covering the entire microwave band is feasible. The technology requirements and self-aligned AlGaAs/GaAs HBT process for multifunction chip application are described. The performances of HBTs, MMIC, and high-speed digital circuits fabricated on the same wafer are reported.<<ETX>>