Low sensitivity complex image rejection filter for GNSS receivers

In this paper, a new approach for the design of a low sensitivity complex-filter is proposed. The approach is based on realising the filter using low sensitivity allpass sections. The complex filter obtained can be used as image-reject filter in low-IF GNSS receivers. The filter configuration is modular, i.e. is composed of the same subcircuits which simplifies the design of the circuit. A Chebyshev type OTA-C image-reject filter obtained by cascading two third-order allpass-based complex filters is presented. Post layout simulation results of the filter using SPECTRE in CADENCE design tool verifying its proper operation are provided.