Direct RF under sampling reception method with lower sampling frequency

摘要

In conventional RF under sampling front ends the sampling frequency is greater than the anti-aliasing filter's bandwidth, which is usually larger than the desired signals bandwidth. In this paper a technique for lowering the sampling frequency required for an RF under sampling receiver is presented. Mathematical expressions to ensure that signal integrity is preserved have been derived. Using these expressions the minimum sampling frequency required is halved. To validate the technique, simulation and measurement of a front-end using the conventional and the proposed techniques has been performed. In the simulation the conventional and proposed techniques achieved SNRs of 22.8 dB and 22.4 dB respectively. The measured SNR for the conventional technique was 19.8 dB and 20.3 dB for the proposed. Using QPSK modulation the EVM was measured to be −19.8 dB for the conventional and −19.5 dB for the proposed techniques.