Compact frequency multiplier using an artificial left-handed transmission line

This paper presents a compact size frequency doubler using an artificial transmission line design approach. The multiplier features conversion gain and high fundamental signal rejection. The frequency multiplying is employing the current combining push-push technique. Two GaAs FETs are driven by 900 MHz anti-phase signals from a simple LHM-TL phase shifter instead of the conventional balun/power divider. The transistor can be loaded directly onto the input and output port of the LHM-TL phase shifter since FETs virtually need no input power. The experimental results show the excellent agreements between the design and ADS^reg simulations. The frequency doubler has a conversion gain of 5 dB and 30% of size reduction compare to the conventional transmission line/hybrid circuit implementation.