Parametric Amplication of Time-varying Transmission Lines (TVTL) and its Applications
Time-varying transmission lines (TVTL) has recently been introduced as one of the most promising transmission line structures that offers non-reciprocal frequency translation without magnetic materials [1-4]. Its sinusoidal parametric amplification with almost no noise penalty has been widely discussed and applied in building components such as broadband circulator. In this research, this parametric coupling mode was applied as a parametric mixer in frequency translational RF receiver. The frequency translational RF receiver can select the desired received band in the presence of undesired adjacent-channel blockers without suffering much signal-to-noise (SNR) degradation.
Exponential parametric amplification is another parametric amplification mode in TVTL that has not yet been fully explored. It can be achieved by designing the cutoff frequency of TVTL to short-circuit the upper sideband of converted signals. Recent measurements on a 12-unit TVTL chip showed proofs of the theory of exponential parametric amplification at signal frequency. A maximum of 2.43 dB insertion loss improvement was observed at 1.2 GHz with a 21.4 dBm carrier driven at 6 GHz. Furthermore, the noise figure of TVTL in exponential amplification region was generally better than that of the passive TVTL, indicating a better noise performance with the help of exponential amplification.