A novel DC-cancellation architecture for direct conversion receivers

A master-slave DC-cancellation system, that allows reduction of built-in low-frequency noise inherent to a direct conversion receiver at the baseband level, has been studied and designed. The system can ideally totally cancel the noise produced by the local oscillator leakage to the antenna, as well as the flicker noise provided by the down-converters. The system features an analog dummy loop used to collect the leakage and reproduce the flicker noise. Using the same structure as the useful path, it is able to subtract noise by integration and re-injection into the system. The performances of the system are limited only by the gain mismatches between the dummies and the paths they correct as well as leakage or noise mismatches between them. A study of nonidealities is also performed.