Patent ID: 7359686

Claim:
A signal amplifier circuit, comprising: an amplitude-modulated (AM) amplifier, operable to amplify an input AM signal, the AM amplifier comprising: a first stage comprising a high-impedance input terminal operable to receive the input AM signal; a second stage coupled to the first stage and operable to provide a gain of greater than one to an output of the first stage; and a third stage coupled to the second stage, the third stage comprising a low-impedance output terminal operable to output an amplified AM signal; a frequency-modulated (FM) amplifier operable to amplify an input FM signal, wherein the FM amplifier comprises a plurality of feedback paths and wherein an input impedance and an output impedance of the FM amplifier are substantially constant as a frequency of the input FM signal varies; an automatic gain control (AGC) circuit comprising: a first root-mean square (RMS) detector operable to measure an RMS voltage level of an input signal received by the AGC circuit; and a first level adjuster, operable to adjust a voltage level of the input signal received by the AGC circuit based on the RMS voltage level measured by the first RMS detector; wherein the AGC circuit is operable to receive as the input signal an output signal of at least one of the AM amplifier and the FM amplifier and adjust the voltage level of that output signal; a voltage supply operable to draw current from a source and to output a substantially stable voltage level at an output terminal; wherein the AM amplifier, the FM amplifier, and the AGC circuit are coupled to the output terminal of the voltage supply.