A 6.3µW 20b incremental zoom-ADC with 6ppm INL and 1µV offset

Incremental analog-to-digital converters (ADCs) can be applied in many instrumentation applications, such as the readout of bridge transducers and smart sensors [1-4]. Such applications require ADCs with high absolute accuracy and linearity, as well as high resolution. Moreover, since the signals of interest are typically near DC, such ADCs must employ robust offset and 1/f noise-reduction techniques. Fulfilling these requirements often results in ADCs with poor energy efficiency, thus preventing their use in systems powered by batteries or energy scavengers. This paper describes a micro-power incremental ADC that achieves 20b resolution, 1μV offset and 6ppm INL, while dissipating more than an order of magnitude less energy than ADCs with comparable precision [3-6]. This is achieved by the use of a 2-step or zoom ADC architecture [1,2], an inverter-based integrator, and various dynamic error-correction techniques.