Mixed-signal quadratic operators for the feature extraction of neural signals

This paper presents design principles for reusing charge-redistribution SAR ADCs as digital multipliers. This is illustrated with an 8-b fully-differential rail-to-rail SAR ADC/multiplier, designed in a 180 nm HV CMOS technology. This reconfigurability property can be exploited for the extraction of product-related features in neural signals, such as energy content, or for the discrimination of spikes using the Teager operator.