Voltage Amplification of Radio Frequency Signals With Pitch-Asymmetric Acoustic Delay Lines

We present the conceptual approach, theoretical simulations, and experimental results of a novel device based on acoustic delay lines with different pitch between transmitter and receiver (dubbed pitch-asymmetric delay lines) for passive voltage amplification of radio frequency signals. The theoretical results show that it is possible to attain very high voltage gains in this new class of asymmetrical delay lines. The experimental results validate the ability to produce voltage gain, but significantly below theoretical predictions. We attribute this discrepancy to the high admittance at the nulls of the experimental response of the interdigital transducers. We investigate the maximum admittance at the nulls compatible with obtaining high voltage gains ( $>20~dB$ ) and find that it is two order of magnitude lower than that achieved in this work. [2019-0209]