Evaluation techniques of frequency-dependent I/Q imbalances in wideband quadrature mixers

Abstract

As bandwidths of digital wireless communications get wider, it is essential to evaluate the I/Q imbalances among quadrature mixer ports in terms of the mismatch characteristics of the analog components in the I and Q paths and the carrier phase offset. This paper describes a technique to evaluate frequency-dependent I/Q imbalances and carrier phase offset in wideband quadrature mixers. Using an SSB stimulus, the response of a DUT with imbalances is modeled mathematically, and an identification algorithm using a unique input stimulus is constructed. The validity of this technique is confirmed using an actual WiMAX transceiver on an ATE.