Low Cost, Power-Efficient Reconfigurable Passive FET Mixers

Abstract

This paper describes a novel resistive passive FET mixer co-designed with a reconfigurable VCO (voltage controlled oscillator) that acts as a LO (local oscillator), can operate with low noise figure, and high dynamic range without the need of external balun (balance-to-unbalance) network. In this approach, dynamic slope optimizer network, which drives and resonates the gates of the mixing cell (Dual-FETs) for a given conduction angle of the differential (180deg phase shift) VCO output is adapted to meet the challenge of the conflicting requirements such as linearity, conversion loss, and noise figure. By introducing dynamic feedback mechanism by incorporating series resistor and capacitor between the drain and gate of the mixing cell (Dual-FETs) network, impedance level can be optimized for minimum loss of the RF signal, thereby; it improves the flatness of the conversion loss over the operating frequency band. The typical measured input intercept points (IIP3) and conversion loss is 39 dBm and 8.5 dB with the LO power typically 15dBm for the frequency bands (RF: 1150-2450 MHz, LO: 1200-2650 MHz, IF: 50-200 MHz).