Michael G. Adlerstein

Measurement of series resistance in IMPATT diodes

A new method is given for determining the electrical series resistance of an IMPATT diode. The measurement is based on observation of the oscillation threshold bias current for a diode in a standard circuit. The method is applied to GaAs diodes near 40 GHz. The values obtained are used to quantitatively explain other performance characteristics of the diodes.

Thermal resistance measurements for AlGaAs/GaAs heterojunction bipolar transistors

A method for the measurement of the thermal resistance of heterojunction bipolar transistors (HBTs) has been developed. The measurement technique is described and its application is illustrated. Results for single-emitter HBTs are explained with the help of a model for HBT thermal resistance. Measured values agree with the predictions of the model for heat flow for single-emitter HBTs. >

Thermal stability of emitter ballasted HBT's

A simple analytical model is derived for thermoelectronic stability in heterojunction bipolar transistors (HBTs). An expression is presented for the value of emitter ballast resistor needed to stabilize the transistor. The result leads to a stability diagram on the current-voltage (I-V) plane which aids in the selection of emitter ballast resistors.

Ka-band GaAs HBT PIN diode switches and phase shifters

In this paper, we present results on millimeter-wave PIN diode switch arms and phase shifters fabricated in our HBT process line. The PIN diode is formed by the base-collector junction of the HBT and is therefore completely compatible with our conventional HBT process. A SPST switch arm exhibited 0.7 dB insertion loss and 21 dB isolation at 35 GHz. A high power version of this switch was capable of handling 29.5 dBm input power with less than 1 dB insertion loss at 17 V reverse bias. Low-pass/high-pass phase shifter bits with relative phase shifts of 45, 90, and 180/spl plusmn/10 degrees up to 36 GHz have also been demonstrated using HBT PIN diodes as switching elements. To our knowledge, this is the first demonstration of HBT PIN diode circuits at Ka-band. A detailed discussion of the circuit designs and measurements are given in the paper.<<ETX>>

Double-velocity IMPATT diodes

A new IMPATT diode structure is proposed. The device incorporates a heterojunction between materials having different electric field saturated carrier velocities. Analysis shows that such a diode can have significantly higher dc-to-microwave-power conversion efficiencies than conventional Read IMPATT diodes.

Pulsed 1-watt heterojunction bipolar transistors at 35 GHz

High-peak-power pulsed operation of common emitter AlGaAs-GaAs HBTs, at 35 GHz is reported. A 1.0-W peak power with 2.3-dB associated gain and power-added efficiency of 28% is obtained. Small devices gave up to 43% power-added efficiency with 190-mW output at 4.8-dB gain. The pulse length was 300 ns, and the duty cycle was 33%. The device design, small-signal characteristics, and power results obtained are described.<<ETX>>

Avalanche response time in GaAs as determined from microwave admittance measurements

Microwave admittance measurements in a high power GaAs double-drift Read diode are fitted to an analytical solution to the Read equation. The data can be explained within experimental error by the classical expression for intrinsic avalanche time\tau_{i} = l_{a}/3v_{S}. This is at variance with the prediction that τiin GaAs may be anomalously long.

Millimeter-wave GaAs read IMPATT diodes

We have designed, fabricated, and evaluated gallium arsenide Read IMPATT diodes for Ka-band (36-38 GHz)operation. The devices were packaged units intended for manufacturability and high yield. Oscillator output power as high as 710-mW CW was obtained at 9-percent efficiency. This paper describes design and fabrication techniques employed and discusses the potential and limitations of such devices.

A Ka-band HBT two-stage LNA

A Ka-band HBT two-stage LNA has been developed. This circuit is to be used in a multifunction T/R module which includes both analog and digital functions. The measured noise figure is 5 dB from 30 GHz to 34 GHz, with an associated gain of better than 7.5 dB. A single-stage LNA has also been developed. The measured noise figure is 4 dB from 33 GHz to 35 GHz with an associated gain of 4 dB. These results are the best yet reported at Ka-band for a HBT LNA. The amplifiers have been designed to minimize the noise measure.

35 GHz pulsed HBT MMIC amplifiers

A three-stage MMIC preamplifier and a two-stage power amplifier using GaAs/AlGaAs Heterojunction Bipolar Transistors (HBTs) have been developed for pulsed-power applications at 35 GHz. Both amplifiers have been fully characterized at 35 GHz with RF input power and base bias pulse wave forms having 33% duty cycles and 300 nS pulse lengths. The preamplifier delivers a peak output power of 19.6 dBm at 11% PAE and 12.6 dB associated gain at a bias of VCE=6 V and IC=128 mA. The power amplifier delivers a peak output power of 29 dBm at 15% PAE and 5 dB associated gain after minimal external tuning at a bias of VCE=6 V and IC=600 mA. The monolithic amplifiers reported here are based upon 35 GHz power HBTs and represent the first such amplifiers yet reported.<<ETX>>