A novel DC-offset cancelling circuit for DCR

Abstract

This paper describes a novel DC-offset canceling structure for Direct-Conversion Receiver (DCR). The proposed structure uses an I/Q tuning loop to remove DCoffset. I/Q mismatch issue is discussed and according solution to suppress I/Q mismatch effects is adopted. A variable bandwidth technique is employed to accelerate the loop acquisition when the system is first time turned on. Simulation results show that the differential DC-offset voltage is less than 3mV after the loop becomes locked when a DC-offset of 100mV is presented. Moreover, the tuning loop can efficiently suppress effects of I/Q mismatch. © 2005 IEEE.