A non-binary capacitor array calibration circuit with 22-bit accuracy in successive approximation analog-to-digital converters

A novel capacitor array calibration circuit is presented in this paper. A non-binary capacitor array with 20 capacitors is used. The capacitor calibration algorithm is based on a perceptron learning rule, developed for artificial intelligence applications. The capacitor weights are adaptively calibrated to match the physical capacitors with up to 22 bit accuracy. Capacitor matching is not a limiting factor to the resolution. A mixed-signal microcontroller architecture is used to efficiently implement the novel capacitor array calibration algorithm. This calibration circuit is being used to design a 1.5 Mega samples per second (MSPS), 16 bit, 50 mW successive approximation analog-to-digital converter (ADC).