Multi-channel analog-to-digital conversion using a single-channel quantizer

We present a novel analog-to-digital converter (ADC) architecture and conversion scheme to digitize multiple input channels using a single-channel quantizer. The proposed system consists of an analog front-end and a digital back-end. In the analog front-end, bandlimited M-channel sparse signals are discretized using sample-and-hold circuits, and then modulated using pseudo-random binary sequences. After modulation, the modulated signals are summed together before quantization. This mixture is converted to digital sequences with finite resolution followed by a single quantizer. The digital back-end separates the digitized mixture into M-channel digital sequences. For separation, we propose different classes of reconstruction methods that are used in sparse signal representation. The experimental results, with an ideal quantizer, show perfect recovery of the input signals if the input signals have sufficient sparseness. In the case of a realistic ADC with 16-bit quantization noise, the reconstruction is possible up to 108 dB in signal-to-reconstruction error ratio.