An analog-to-digital converter ADC and a method to convert an analog input signal into a digital output signal comprising N bits on, n∈{0, . . . , N−1} is presented. The ADC contains a controller, a digital-to-analog converter DAC, and a comparator. The comparator generates a binary signal by comparing the analog input signal with an analog output signal of the DAC. The controller receives the binary signal generated by the comparator and generates, based on the binary signal, a digital control signal comprising N bits cn, n∈{0, . . . , N−1}. The DAC generates the analog output signal based on the digital control signal generated by the controller. The controller has a register which stores a previous sum value and an adder to determine a test sum value by adding.