Gain stability arrangement for HV MOSFET power amplifier

摘要

The amplifier includes a linear preamplifier which is coupled to a signal input and has an output. An RF output circuit provides an amplified RF output signal. A number of high-voltage FET are also provided with each having a source-drain current path coupled to the RF output circuit. Each FET has a gate coupled to the output of the linear preamplifier. A temperature sensor is in thermal communication with the transistors and has an output whose level varies in accordance with the temperature of the transistors. A short-term (minutes) gain stability compensation circuit is coupled to the temperature sensor output and controls the drain voltage. A short-term (seconds) gain stability compensation circuit has an input coupled to the RF output circuit and coupled to control the gain of the linear preamplifier means to compensate for short term changes in the RF output signal level.