COMPLEX BANDPASS DeltaSigmaAD MODULATOR, AD CONVERSION CIRCUIT AND DIGITAL WIRELESS RECEIVER

摘要

PROBLEM TO BE SOLVED: To obtain a complex bandpass ΔΣAD modulator achieving high speed though having a simple arrangement. SOLUTION: In the complex bandpass ΔΣAD modulator 7, an input complex analog signal is passed through subtractors SU31 and SU32 and a complex bandpass filter 10, AD-converted through AD converters AD11 and AD12 into a complex digital signal, and DC-converted through DA converters DA11 and DA12 into a complex analog signal which is then subtracted from the input complex analog signal and outputted. Multiplexers MU1 and MU2 input and output the complex digital signal alternately to/from the DA converters DA11 and DA12 to generate a DA converted analog signal. DWA logic circuits DL1 and DL2 are provided at prestages of the DA converters DA11 and DA12 and employ a high-pass element rotation method for an I signal of the complex digital signal and a low-pass element rotation method for a Q signal thus obtaining a complex analog filter. COPYRIGHT: (C)2006,JPO&NCIPI