In this paper, we address the architecture of an antenna diversity receiver. An innovative architecture has been introduced based on code multiplexing, it significantly reduces the power consumption of the front-end. This architecture uses the direct sequence spread spectrum technique in order to multiplex the different antennas contributions through a single IQ demodulator. This paper address the performances of this kind of architecture. Simulation and measurement results show that, in a Gaussian case, the bit error rate does not increase significantly with the multiplexing. IQ imbalance study shows that the new architecture has the same sensitivity to IQ mismatches than the classical stack-up architecture.