Patent ID: 8305142

Claim:
A circuit comprising: a first node for passing a first input signal for amplification by an amplifier, the first input signal having a fundamental frequency, the amplifier being assumed to add unwanted distortion to an amplified first input signal stemming from generation of a multi-ordered harmonic of the fundamental frequency; and a predistortion circuit connected to the first node without being connected to the output of the amplifier, the predistortion circuit comprising: a single input/output node coupled to the first node, wherein the single input/output node both receives the first input signal at the first node and provides at the first node a predistortion output signal of the predistortion circuit, derived from the first input signal, that is applied to an input of the amplifier; a first capacitor having a first terminal connected to receive the fundamental frequency, the first capacitor having a second terminal; a forward biased diode junction connected to receive the fundamental frequency from the second terminal, the diode junction conducting a forward biased current and generating at least a second harmonic of the fundamental frequency; and a second capacitor connected to the diode, the second capacitor receiving at least some of the forward biased current such that a combination of at least the diode and the second capacitor generates an inverted signal having a frequency approximately equal to the second harmonic of the fundamental frequency, wherein the inverted signal is coupled through the first capacitor to the first node for providing the predistortion output signal to the first input signal.