Design of sub-harmonic mixer MMIC for EHF satellite links

Abstract

This paper presents the design flow of a compact GaAs MMIC for Extremely High Frequency (EHF) satellite communications. The proposed circuit enables sub-harmonic mixing capability and integrates a LO buffering section, thus allowing for low frequency and low power reference signal interface. Circuit design is described in detail providing a comprehensive view of the followed theoretical approach, starting from mixer core definition until the complete synthesis of LO/RF/IF interfaces. In particular, the design flow of an innovative three-conductor Marchand balun is deeply analysed. Fabricated MMIC operates in the 43.5-50 GHz band and results in a compact layout (2.4 × 2.4mm2) featuring a port-to-port isolation better than 25 dB with a typical conversion loss of 12 dB.