Channelized front-ends for broadband signal processing with sub-band dynamic range control

Abstract

A frequency-folded analog-to-digital converter (FF-ADC) simultaneously channelizes and digitizes a broadband input signal, while using a single LO. The broadband signal is downconverted and aliased in polyphase signal paths. The aliased signals are band-limited and are individually digitized using low-frequency sub-band ADCs. Channelization is performed using harmonic rejection after digitization. In this work an FF-ADC architecture is described wherein the sub-bands can be individually attenuated before the ADCs. This helps to relax the dynamic range requirement of the ADCs in the presence of a large variation over frequency in power spectral density in the broadband input signal. It is also shown that sub-band rejection better than 15 dB can be achieved for selected bands, without calibration, while the rest of the sub-bands are downconverted with equal gain. The approach is verified in simulation.