Push=pull RF power amplifier

摘要

The amplifier includes first and second high voltage FETs (Q1,Q2). Each FET has a semiconductor die region which is contained at a predetermined location within a heat transmitting base. A minimal number of transformers are employed with an impedance matching transformer (T1) feeding an input balun (T2) which supplies the input signal in a push-pull to the gates of the FETs. The first and second FETs are mounted on a heat conducting spreader plate in heat transfer relation. A strap formed from aluminium or fibreglass is attached onto the spreader plate and sandwiches the first and second transistors between the strap and the plate. The strap is superimposed over the locations of the semiconductor die regions. A temperature sensor is mounted on the spreader plate at a position between the transistors. A bias device coupled to the temperature sensor adjusts a voltage applied to the transistors according to detected changes in temperature.