Multi-stage quadratic amplitude modulator capable of compensating for the quadratic phase deviation of a carrier pair

摘要

In a demodulator for demodulating a multilevel quadrature amplitude modulated signal into inphase and quadrature demodulated signals (ID) and (QD), a processing unit (10) processes the multilevel quadrature amplitude modulated signal to produce inphase and quadrature processed signals (IDS) and (QDS). An inphase phase controller (20) is supplied with an inphase control signal and the inphase and the quadrature processed signals and produces an inphase phase controlled signal as the inphase demodulated signal. The inphase demodulated signal comprises an inphase data signal and an inphase error signal. A quadrature phase controller (21) is supplied with a quadrature control signal and the inphase and the quadrature processed signals and produces a quadrature phase controlled signal as the quadrature demodulated signal. The quadrature demodulated signal comprises a quadrature data signal and a quadrature error signal. An inphase multiplier (22) multiplies the inphase error signal by the quadrature data signal and produces an inphase multiplied signal as the inphase control signal. A quadrature multiplier (23) multiplies the quadrature error signal by the inphase data signal and produces a quadrature multiplied signal as the quadrature control signal.