Posted on Jul 7, 2012 6593
This 60-W. 28-V broadband amplifier covers the 225-400 MHz military communications band. The amplifier may be used singly as a 60-W output stage in a 225-400 MHz transmitter. or by using two of these amplifiers combined with quadrature couplers, a 100-W output amplifier stage can be constructed. The circuit is designed to be driven from a 50-0 source and work into a nominal 50-0 load. The input network consists of two microstrip 1-sections composed of Z1, Z2, and C2 through C6.
C1 serves as a deblocking capacitor. A 4:1 impedance ratio coaxial transformer T1 completes the input matching network. L1 and a ferrite bead serve as a base decoupling choke. The output circuit consists of shunt inductor 12 at the collector, followed by two microstrip L-sections composed of Z3, Z4, and C8 through Cl1. C12 serves as a de blocking capacitor, and is followed by another 4:1 impedance ratio coaxial transformer. Collector decoupling is accomplished through the use of 13, U, C14, C15, C16, and Rl.