Sampling receiver with multi-branch sigma-delta modulators and digital

Abstract

An IF sampling receiver for use in a wireless communication system includes first and second channels, with one channel generating an in-phase (I) component of an incoming analog IF signal, and the other channel generating a quadrature (Q) component of the analog IF signal. Each of the two channels of the IF sampling receiver includes a corresponding sigma-delta modulator channel. Each of the two sigma-delta modulator channels may be separated into m parallel branches by applying a polyphase decomposition technique to one or more resonators associated with the sigma-delta modulator. The invention thus provides a general framework for configuring a given channel of a sigma-delta modulator to include m parallel branches. The invention also provides a technique for separating a given sigma-delta modulator into n parallel channels, where n is greater than 2. Each of the n parallel channels may then be separated into m parallel branches. Mismatch between the first and second channels of the IF sampling receiver may be corrected by using a ratio of first and second channel power levels, as measured during a calibration mode, to multiply one of the I or Q components during normal operation, such that the I and Q components are brought back into balance to a first order approximation.