Optimum bias conditions for linear broadband InGaP/GaAs HBT power amplifiers

Abstract

Absfract -A design strategy for a linear broadbandInGaPlGaAs HBT power ampUfier is presented. This design takes advantage of the bias dependence of the nonlinear basecollector charge, expressed by the CK w VcE and k vs 1 , characteristies ofthe device. Using this technique, it Is shown that the second and third order distortions have separate optimum bias conditions, and furthermore, there is an distortions. This strong bias dependence of the uonUnear orders of distortion are verified on a 24" 0.5-11GHz

A High-Linearity Tapered Distributed Amplifier for Ultra-Wideband-Applications

“…The transistors are biased through the collector line by means of an external bias tee. The bias point was selected at the maximum of f t to achieve good linearity and high gain [1]. The chip size is 1.51 x 1.12 mm 2 .…”

“…In contrast a distributed amplifier can overcome the gain-bandwidth limitation. The principle of distributed amplification using discrete transistors is a technique where the input-and output capacitances of the transistors are combined with lumped inductors to form artificial transmission lines according to (1).…”

“…Wide bandwidth and high linearity amplifiers are essential in such applications. Typically high bandwidth and linearity are critical specifications and efficiency is a less important requirement [1]. One of the major challenges is to maintain high linearity over the entire bandwidth since narrow-band linearization techniques cannot be utilized.…”

250 MHz TO 30 GHz, UNILATERAL CIRCUITMODEL FOR INGAP/GAAS HBT

“…Meanwhile, analytical formulations like distortion analysis [1,2], non-linearity analysis [3][4][5], distributed amplifier design [1,6] and other applications [7,8] are derived based on simplified unilateral model assumption for the active device. In the area of model parameter extractions, many techniques, [9][10][11], have been presented to accurately extract active device small signal model parameters using bilateral model.…”

“…However, there is lack of published work on the extraction of an ultra wideband unilateral model and the model parameters. Some research works [3,4,12] who have used simplified unilateral model for their analyses assume that the base-collector feedback capacitance and emitter feedback resistance are very small and are simply neglected. When the voltage gain is much greater than one, feedback capacitance effectively shape input impedance.…”