A Novel High-Speed Parallel Sampling Technique By Analog And Digital Twice Mixing

This paper proposed a novel parallel sampling technique by twice mixing operation is proposed. Firstly, the input signal is equally split into two channel, and sent to an analog mixer to respectively mix a square wave signal that are out of phase by 180 degrees. The DC and first-order harmonic component allows the entire component of the input signal to be folded into the same Nyquist sub-band of the digitizer after low-pass filtering. Secondly, the filtered signals are digitized synchronously at the same sampling clock. A pair of linear phase FIR filters can be implemented to easily compensate the non-ideal or the mismatch of the digitizers in a whole sub-band. Finally, remix the sampled data respectively after digital down conversion, and the results are combined to obtain the parallel sampling result. The technique is step by step deduced and analyzed mainly based on the frequency domain method. Through a rational design the resulting signal spectrum substantially matches the original frequency spectrum. Analog and digital twice mixing technique break the bandwidth limit of digitizers, and its performance benefit from the symmetry of the two acquisition and propagation channel.