Broadband Frequency Doubler Design Based on Nonlinear Gaas FET Models

The aim of this paper is to present analysis and design procedures for a broadband frequency doubler. Based on these procedures a simple circuit that achieved 6 dBm output signal in 8-18 GHz band with 10 dB conversion loss was built. Our circuit consisted only of two single gate FETs. Careful analysis allowed us to achieve performance that was available in the past only by much more complicated circuits (which involved dual gate FETs or additional amplifier stages). The paper focuses on nonlinear behavior of the doubler. Some general properties of nonlinear circuits are proved and used to predict the doubler behavior. The results obtained agree well with computer simulation and performance of the real doubler.