Adjustable Radio Frequency Front End Receiver for SDR and CR Applications Employing Noise Cancelling

This paper presents a highly linear radio frequency front end (RFFE) receiver (Rx) with its frequency response characterized by having an adjustable shape, center frequency, and bandwidth (BW). The RFFE Rx output is sampled at an adjustable sampling rate to be fed to an ADC for further baseband processing. The architecture employs a generalization of noise cancelling theory to reduce the noise figure (NF) by including an auxiliary path besides its main path to be able to subtract the noise at the output. Simulated on 65 nm technology, this method is proved to reduce the NF from 6.5 dB to 3.5 dB for a selected filter impulse response and down to 2.3 dB in case of implementing a Sinc frequency response.