Internal calibration techniques for quadrature receiver mismatch errors

摘要

The performance of systems requiring the use of quadrature receivers is significantly degraded in the presence of mismatch errors between the In-phase (I) and Quadrature (Q) branches. This paper discusses the mismatch problem and introduces promising solutions. These solutions are independent of communication format, which improves the generality and flexibility of the techniques. Current literature emphasizes estimation of either local oscillator (LO) mismatch or frequency dependent path mismatch using an external calibration signal. This paper develops techniques to estimate both LO mismatch and path mismatch using internally generated calibration signals derived from the system local oscillator. Once the mismatch errors are obtained, LO mismatch can be corrected by analog adjustment and path mismatches are corrected digitally.