The IQ Imbalance Model

Both analog In-phase and Quadrature (IQ) modulator and demodulator may introduce IQ imbalance. If it is left uncompensated, the system performance will be impaired. In this chapter, we first derive the IQ imbalance model without any other impairments. Then, we consider the IQ imbalance model in presence of frequency offset and phase noise. After that, we consider the IQ imbalance model in multiple antenna systems, firstly space-time or space-frequency encoded systems, then spatial multiplexing systems. At the end, we show the signal-to-interference ratio (SIR) degradation due to the IQ imbalance.