Low-power passive frequency doublers of high efficiency using varactor diodes

Abstract

Low-power frequency doublers with high conversion efficiency are required for passive transponder applications in the L and S bands. Varactor diodes have been investigated in this work and designed to work at maximum efficiency for an input frequency of 1250 MHz. The experimental conversion efficiency obtained was 71% as compared to 74% from the theoretical analysis. Owing to physical constraints this relatively high efficiency is obtained only for a limited input power range near 10 mW.