Analysis of harmonic termination impedance on RF/microwave multiplier efficiency

Harmonic terminating impedances have been shown to drastically effect the performance of RF/microwave frequency multipliers. In the literature, various apparently differing conclusions have been obtained on the proper terminating impedances for active multipliers to achieve optimum performance. This paper presents a rigorous and concise approach leading to the determination of harmonic terminating impedances for optimum efficiency. The approach is illustrated in HEMT frequency multipliers in S and C bands. Results have been obtained which have conversion gains of 6 dB with harmonic suppression of greater than 25 dBc utilizing this approach.