Planar broadband MIC balanced frequency doublers

Broadband microwave frequency doublers employing beam-lead Schottky barrier diodes in a novel planar balun configuration are presented. The doubler circuits can be scaled to different frequency bands. Two circuits have been developed with a nominal output power of +11 dBm covering the 6-18 GHz and 10-27 GHz bands, respectively. The output power level is sufficient to provide local oscillator power for unbiased single-balanced mixers. Excellent performance was achieved, combined with a wide operating bandwidth and flat frequency response. A minimal conversion loss of 8.4 dB and an output frequency ratio exceeding 1:3 were achieved. The high fundamental frequency isolation is of special note. A reverse operation mode is presented. It allows one to optimize the performance at low input power levels by forward-biasing the diodes.<>