Low-cost auto-calibration of passive polyphase filter in image reject receiver

A low-cost auto-calibration technique of Radio-Frequency (RF) Passive Polyphase Filter (PPF) for high image rejection in low Intermediate Frequency receiver is presented. The resistance values of the filter are process and temperature dependent with great mismatch constraints especially in the RF domain. That can severely impact the circuit performances if not controlled. In order to overcome this limitation, an in-line auto-calibration of the PPF resistance values, based on Design Of Experiment (DOE) methodology, is presented. Using DOE, a model is derived from thermal and process deviations of the chip responses. This approach results in a robust and low-cost solution.