Patent ID: 7558333
Filing Date: 2009-07-07
Classification: H04L

Abstract:
1. A method of minimizing the distortion caused by a saturated power amplifier or up-converter or RF circuit to phase modulated signals, the method comprising the steps of: mapping k bits d=(d feeding a coefficient cos φ(d) to a first finite impulse response filter for summing a series of the delayed filter coefficients {p(j)} weighted by the symbol coefficients {cos φ(d)} to form a filtered in-phase signal; and feeding a coefficient sin φ(d) to a second finite impulse response filter for summing a series of the delayed filter coefficients {p(j)} weighted by the symbol coefficients {sin φ(d)}to form a filtered quadrature signal, wherein the filtering of the in-phase signal and the quadrature signal with a pulse shaping function p(t) of L≧2 symbols long, and the pulse shaping function satisfies: where x(t) is the convolution of p(t) and p(LT s −t), T s is the symbol time; when the impulse response p 1 (t) of the saturated power amplifier is known, the function x(t) is the convolution of g(t)=p(t)*p 1 (t) and g(T−t), where T is the duration of g(t).