A novel adaptive equalizer and compensator for direct conversion receivers

Abstract

A novel adaptive algorithm is proposed in this paper to remove I/Q mismatch, the second-order intermodulation (IM2), lSI and A WGN simultaneously in a direct conversion receiver (DCR) by using cascaded adaptive filters. 1M2 signals are treated as variable real DC values both in in-phase and quadrature channels separately, so they can be removed simultaneously with only one complex tap incorporated into a complex feed forward equalizer (CFFE). In addition, a real valued adaptive mismatch canceller is employed before the CFFE. Furthermore, a complex decision feedback equalizer (CDFE) is employed to cancel the residual lSI. To accelerate the convergence rates of the taps and to reduce the estimation variance, an internal iterative algorithm is introduced. Simulation results are provided to verify the superior performance of the proposed method.

An Adaptive Filtering Algorithm for Direct-Conversion Receivers: Architecture and Performance Analysis

“…It is obvious that the adaptations of and influence mutually. Hence, we propose an internal iterative algorithm below to accelerate the convergence of the algorithm and to reduce the estimation variance [8].…”

“…By estimating the coefficients in the model during the training period, the desired signal can then be estimated by the decision feedback method. To accelerate the convergence of the algorithm and to reduce the estimation variance, an internal iterative algorithm is introduced [8]. On top of that, the convergence analysis of the proposed algorithm is given, and the closed form of the MMSE of the algorithm is derived as the lower bound of its performance.…”

“…A real valued adaptive mismatch canceller is employed to cancel mismatch, and the varying dc offsets are removed by one complex tap [3], [8]. In addition, the flicker noise is modeled as a complex AR random process (Fig.…”