Parametric characterization of six-port interferometer demodulator through mixer modeling

Abstract

Functional parameters of six-port demodulator are studied in this paper. Indeed, noise figure (NF), conversion loss and inter-modulation products, which are the key parameters of a mixer, are derived through theoretical analysis and validated by simulations. In order to reduce the conversion loss while keeping the power detector's working condition in the square law region and maintain the benefits of low-power LO, the detector biasing technique is also investigated. Also, by modeling the six-port interferometer as a mixer, a platform of extracting a set of equivalent mixer parameters through circuit simulations is proposed. As a case study, the proposed technique is applied to extract the mixer model of a six-port interferometer demodulator operating in E-band with a commercial diode of Avago HSCH-9161. Such a modeling technique provides RF receiver designers a quantitative way of understanding the six-port interferometer demodulators and comparing them with traditional mixer-based zero-IF demodulators.