Estimation and compensation of I/Q linear phase imbalance based on the generalized cross correlation and cross-power spectrum phase method

Abstract

The in-phase/quadrature (I/Q) imbalance results in insufficient mirror frequency attenuation, which must be enhanced using additional analog or digital signal processing. This paper proposes a novel method to solve the estimation of I/Q linear phase imbalance (LPI), which is the main part of the I/Q imbalance. LPI consists of time delay deviation (TDD) and local oscillator (LO) phase offset. Generalized Cross Correlation (GCC) and Cross-power Spectrum Phase (CSP) are commonly used methodologies of TDD calculation. Compared with other conventional methods of applying GCC or CSP alone, the proposed approach combines GCC and CSP to joint estimate LPI without additional hardware, where GCC is utilized to evaluate TDD and CSP is applied to estimate the LO phase offset with the TDD estimation value from GCC. The MATLAB simulation is utilized to evaluate the effectiveness of the proposed method. The experimental results of the complete suppression of the mirror frequency and the correct constellation show that LPI has been accurately estimated and compensated with the appropriate compensation structure.