US Patent 7368874 Dynamic depressed collector

A biasing system for use with a multi-stage depressed collector of a high power amplifier includes one or more adjustable power sources. A power controller provides control signals to the power sources depending on the operational RF power level. For low power applications, biasing of collector electrodes is reduced such that savings in energy costs are realized, and operational temperature and wear are reduced. The control signals are based on values stored in a look-up table. For multiple depressed electrodes, biasing can be controlled in tandem or independently.