US Patent 10256834 Analog to digital converter

An analog-to-digital converter (“ADC”) has an input terminal configured to receive an analog input voltage signal. A first ADC stage is coupled to the input terminal and is configured to output a first digital value corresponding to the analog input voltage signal and an analog residue signal corresponding to a difference between the first digital value and the analog input signal. A second ADC stage is coupled to the first ADC stage and is configured to convert the analog residue signal to a second digital value. At least one of the first ADC stage and the second ADC stage includes a first sub-stage configured to convert an analog signal to a first number of bits of a digital value representing the analog signal, and a second sub-stage configured to convert the analog signal to a second number of bits of the digital value, where the second number of bits is greater than the first number of bits. A controller is coupled to the first and second ADC stages and configured to combine the first digital value and the second digital value into a digital output signal representing the analog input voltage signal.