Patent ID: 6191649
Filing Date: 2001-02-20
Classification: H03D,H04L

Abstract:
A quadrature demodulator, comprising:a receiving circuit for receiving a quadrature modulated signal;a local oscillator for generating a local carrier;a complex multiplier for demodulating a quadrature modulated signal by complex-multiplying the quadrature modulated signal with the local carrier generated in the local oscillator;a symbol error detector for detecting a symbol error between the carrier of the modulated signal and the local carrier determined from the signal demodulated at the complex-multiplier;a feedback loop for controlling the local carrier generated at the local oscillator by feeding back the symbol error detected at the symbol error detector to the local oscillator;a numerical control oscillator for generating a recovered phase signal under the control of the symbol error branched from the feedback loop; andan error detector for compensating the local carrier to reduce the symbol error according to the recovered phase signal.