Asynchronous capacitive SAR ADC based on Hopfield network

Abstract

This letter revisits a Hopfield network for an SAR ADC configuration, which enables low voltage, low power and fast operation with small circuitry. It employs an asymmetrical Hopfield network to avoid local minimum, and it uses capacitors and switches instead of very large resistors. Our N-bit SAR ADC uses N chopper-type comparators with asynchronous parallel operation, which is different from the conventional asynchronous SAR ADC employing only one comparator. It requires only the sampling clock for each input data sampling; no internal high frequency clock is required. Its AD conversion time is determined only by the comparator delays and the capacitor charge/discharge settling times; hence it is very fast and the AD conversion latency is only one or two clock cycles. Its operation is verified with SPICE simulations.