X-band Power Amplifier Research Articles

A high-power and high-gain X-band Si/SiGe/Si heterojunction bipolar transistor

A double mesa-type Si/SiGe/Si (n-p-n) heterojunction bipolar transistor (HBT) with record output power and power gain at X-band (8.4 GHz) is demonstrated. The device exhibits collector breakdown voltage BV/sub CBO/ of more than 24 V and a maximum oscillation frequency f/sub max/ of 37 GHz. Under continuous-wave operation and class-AB biasing conditions, 24.2-dBm (263-mW) RF output power with concurrent gain of 6.9 dB is measured at the peak power-added efficiency (28.1%) from a single ten-emitter fingers (780-/spl mu/m/sup 2/ emitter area) common-base HBT. The maximum RF output power achieved is as high as 26.3 dBm (430 mW in saturation) and the maximum collector efficiency is 36.9%. The low collector doping concentration together with the device layout result in negligible thermal effects across the transistor and greatly simplifies the large-signal modeling. The conventional Gummel-Poon model yields good agreement between the modeled and the measured de characteristics and small-signal S-parameters. The accuracy of the model is further validated with the measured power performance of the SiGe power HBT at X-band. These results set a benchmark for power performance for SiGe-based HBTs and indicate promise for their implementation in efficient X-band power-amplifier circuits.

An X-band high-power amplifier using SiGe/Si HBT and lumped passive components

We report the design and fabrication of a compact microwave monolithic integrated circuit (MMIC) amplifier, which demonstrates high output power at X-Band. A single-stage power amplifier is demonstrated, with a double-mesa type SiGe/Si HBT as the active device and spiral inductors and MIM capacitors as lumped passive components. At 8.4 GHz, a linear gain of 8.7 dB, an output power at peak efficiency of 23 dBm, and a saturated output power P/sub sat/ of 25 dBm, are measured. To our knowledge, this is the first MMIC X-Band power amplifier using SiGe/Si HBTs.

Integrated electrically tuned X-band power amplifier utilizing Gunn and IMPATT diodes

A totally integrated X-band power amplifier for FM and PM communication system applications having 1-W output power and 30-dB gain is described. The amplifier consists of two electrically tuned injection-locked oscillator stages taht are tunable over a 500-MHz range with 250-MHz minimum locking bandwidth. A Gunn diode is utilized in the first stage and a silicon IMPATT diode in the second stage oscillator for the best overall FM noise, AM/PM conversion, output power, and efficiency. The FM noise and AM/PM conversion of the separate stages are presented in relation to overall amplifier performance. The amplifier design includes a combined power monitor and `out-of-lock' detection circuit. In addition, temperature-compensated current and voltage regulators and automatic interface circuitry to shut off the amplifier when out of lock occurs are described. Temperature compensation for the free-running frequency of each stage over the temperature and frequency range is discussed.