With an ideal model of a six-port communications receiver in mind, the optimal local oscillator (LO) power at the diode mixers for maximum signal-to-noise-ratio (SNR) at the baseband outputs is determined by simulations. The simulation setup contains the equivalent circuit for a diode mixer that has been used in a six-port communications receiver demonstrator [1]. By means of noise analysis and one tone harmonic balance simulations the SNR characteristics with respect to the LO power is derived in the presence of diode shot noise, and of diode shot noise combined with LO phase noise. The results show that a properly adjusted LO power is essential for the receiver performance.
