Patent ID: 7541868
Filing Date: 2009-06-02
Classification: H03F

Abstract:
1. A circuit for pre-distorting a signal input to an amplifier comprising: a signal divider operable for dividing an input signal into signal portions that travel in a primary path and a secondary path; a delay element in each of the primary and secondary paths for introducing a group delay to the signal portions in the respective paths, the delay elements having different values between the paths to introduce different delays to the signal portions in each of the respective paths; a signal combiner operable for combining the signal portions in the respective paths into a combined output signal having an effective delay that is influenced by a combination of the delays of the signal portions in the primary and secondary paths; a variable gain circuit arranged in each of the primary and secondary paths, the variable gain circuits operable, based on the level of the input signal, to vary the level of the input signal portion that each path contributes to the combined output signal and thereby vary the effect of each signal portion delay on the effective delay of the combined output signal for modulating the effective delay of the combined output signal.