DC offsets in direct-conversion receivers: characterization and implications

Since DC-offsets can have a large, negative impact on the performance of direct-conversion receivers, it is important to determine the offset performance of a given design. This article discusses one technique that can be used to characterize and measure dc-offsets in DCR circuit applications. DC-offsets are a primary concern in the design of DCRs and must be characterized in determining the performance of a particular receiver design. By measuring the dc level at the output of a DCR front-end in separate steps, the source of the offsets - device mismatches, LO self-mixing, and second order nonlinearities - can be resolved.