Nonreciprocal Time-Varying Transmission Line With Carrier Boosting Technique for Low-Noise RF Front Ends

A new non-reciprocal time-varying transmission line (TVTL) for low-noise RF front ends is presented in this letter. The proposed design is featured with the carrier boosting technique, where the carrier line is periodically loaded with varactors to boost the carrier signal, hence to improve the conversion gain of the TVTL at high frequencies without deteriorating other performances such as noise and linearity. Implemented in a Rogers circuit board, a prototype of the proposed design achieves an operating frequency range from 0.65 to 1.15 GHz with a measured receiving conversion gain of 5 dB, which is about 10 dB higher than conventional design.