Decision directed scheme for IQ imbalance compensation on OFCDM direct conversion receiver

Abstract

Recently, the direct conversion scheme has been actively investigated for the purpose of cost miniaturization and low power consumption of wireless receivers. IQ imbalance is one of the problems for the direct conversion receiver. In the direct conversion receiver, a pi/2 phase shifter and a double balance mixer (DBM) for the radio frequency (RF) signal is required. However, it is difficult to obtain the accurate phase shifter and the linear DBM over broad bandwidth. As a result, the balance between in-phase (I) and quadrature-phase (Q) of the demodulated signals may be lost. In the case of OFCDM modulations, this IQ imbalance causes intercarrier interference (ICI) in the demodulated signals. In this paper, the decision directed scheme for IQ imbalance compensation is proposed