An Analytical Approach in Analysis of Local Oscillator Near-the-Carrier AM Noise Suppression in Microwave Balanced Mixers

In this paper, a new formulation based on conversion matrix method is proposed to analyze “near-the-carrier local ocillator (LO) noise” down conversion to IF in microwave mixers. This method could be easily applied to analyze LO noise down conversion in any type of mixer. Practical results of this method have been compared with the envelope method and measurement results. It is shown that despite the conventional AM noise suppression in balanced mixers, the near-the-carrier LO noise suppression does not occur necessarily at the center frequency of hybrid in balanced mixers. AM noise suppression values are predicted precisely.