LINEAR HIGH-FREQUENCY AMPLIFIER WITH HIGH INPUT IMPEDANCE AND HIGH POWER EFFICIENCY

A high-frequency power amplifier circuit offers the advantages of high input impedance, good linearity, high power efficiency and accurate bias current control in a compact and economical circuit configuration. The amplifier includes a single-ended output stage driven by a symmetrical push-pull emitter follower stage with both active pull-down and active pull-up capability. The emitter follower stage is driven by an active phase-splitter stage, with bias current for the phase-splitter stage and subsequent stages being provided by a bias-current control stage which is directly connected to the phase splitter stage. A linear voltage-to-current converter stage receives a high-frequency input voltage and provides a high-frequency current signal to the input terminal of the bias-current control stage that controls the current in the output stage.