A comparator tracking scheme for an analog-to-digital converter (ADC) may implement a dynamic window size by varying, over time, a number of comparators powered up to convert an analog input signal to a digital output signal. A comparator-tracking scheme may be implemented, for example, in a controller coupled to a plurality of comparators in an ADC. For example, the controller may determine a window size for the ADC and determine a window position for the ADC. The controller may then activate comparators of the ADC within a window centered at the window position and having a width of the window size. The controller may determine a window size by analyzing an output of a filter. When the filter output indicates a rapidly changing analog input signal, the controller may dynamically increase a window size of the ADC, which may increase a number of comparators powered on.