Design and Development of Higher Order Subharmonic Mixers

Abstract

Microwave mixers are inevitable modules in any RF sub-system. Enabling frequency translation, mixers have always played a pivotal role for venturing into the higher frequency domain. Progressive development in Monolithic Microwave Integrated Circuit (MMIC) technology has enabled the realization of highly condensed and complex core chip RF modules covering THz technology via realization of high frequency mixers employing Schottky diodes. Likewise, the mixing phenomenon has advanced from fundamental mixing to sub-harmonic mixing wherein higher order of lower frequency Local Oscillator (LO) frequency is utilized advantageously making the circuitry compact and avoiding the need for generating higher LO frequencies. This research work involves investigation wherein three novel findings have evolved as an outcome of the research; formulating spurious frequency determination, simplifying fundamental I-Q mixer and realizing 6X Sub-harmonic IQ mixer using improved idlers. The findings are briefly described below: (i) Formulae for Determining Heterodyne System Spurious Frequencies that Coincide with Desired Output Frequency: Till date, no direct formulae have been reported for determination of the lowest order coinciding spurious. (ii) Proposal and Demonstration of a Simplified Design Topology for I-Q mixers: Conventional I-Q Mixers utilize hybrids, vias, cross over or wire-bonds for realization. The proposed design is based on a unique arrangement of six RF power dividers and avoids complex structures like hybrids or vias. (iii) Design and Realization of a 6X Sub-harmonic IQ MMIC using Improved Lumped Component Microwave Multi-Frequency Idler:Two design methodologies for realization of compact and improved microwave lumped component multi-frequency idlers for monolithic integrated circuits have been proposed and using this a 6X Sub-harmonic IQ MMIC Mixer has been designed.