Ultra-wideband GaN Power Amplifiers - From Innovative Technology to Standard Products

Andrey Kistchinsky
Microwave Systems JSC
Russia

Introduction
A number of the modern electronic systems applications require generation, processing, amplification, and emission of signals that have a continuous broadband spectrum or modulated signals with a relatively narrow spectrum whose frequency may change in broad ranges. The first group of applications may include UWB systems of short distance data transmission, radar systems with UWB signals of different kinds (pulse, multi-frequency, or quasi-noise), RFID-systems, and a number of others. The second group includes electronic warfare (EW) systems, EMC-testing systems, as well as universal measuring and testing equipment.
Usually, signals with fractional bandwidth over 20% of band center or more than 500 MHz of absolute bandwidth are referred to UWB signals. As applied to the signal-processing devices, in particular, to amplifiers, the interpretation of the term UWB is somewhat different. Depending on the relative bandwidth the amplifiers are usually divided into the following kinds: narrowband (frequency coverage - relation of the upper working frequency to the lower working frequency (W) is less than 1.2:1); wideband (W from 1.2:1 to 2:1), and ultra-wideband ones (W greater than 2:1). In the present article we shall speak about technologies of microwave ultra-wideband power amplifiers.
The main parameters determining the possibility of using an power amplifier in a definite electronic system are as follows: a working frequency bandwidth (ΔF), the output power with the given criteria of distortion (Po), and the efficiency of transformation DC source power into the output power (DE). With the increase of the frequency coverage W the achieved DE is significantly lowered.