Patent ID: 6859103
Filing Date: 2005-02-22
Classification: H03F

Abstract:
1. A bias circuit for improving linearity of a radio frequency (RF) power amplifier, the RF power amplifier including an RF transistor and a first capacitor, the RF transistor having a collector, an emitter, and a base, the first capacitor having a terminal connected to the base of the RF transistor and another terminal for receiving an RF input signal, the bias circuit comprising: a bias transistor having a collector, an emitter, and a base, the collector being connected to a DC voltage source and the base being connected to a bias voltage source; a second capacitor having a first terminal and a second terminal, the first terminal being connected to the emitter of the bias transistor; and a first inductor having a third terminal and a fourth terminal, the third terminal being connected to the second terminal of the second capacitor and the fourth terminal being connected to a ground; wherein the second capacitor and the first inductor construct a first LC series-connected resonator circuit for directly conducting part of the RF input signal coupled to the bias transistor into the ground, thereby improving linearity of the RF power amplifier.