Ultra-low power comparator with sampling control loop adjusting frequency and/or sample aperture window

Methods and apparatus for minimizing average quiescent current for a desire voltage error in a comparator are disclosed. An example method includes receiving a first voltage and a reference voltage, outputting a second voltage when the first voltage is lower than the reference voltage, wherein the outputting of the second voltage increases the first voltage, counting a number of clock cycles while the first voltage is higher than the reference voltage, comparing the number of clock cycles to a maximum number of clock cycles and a minimum number of clock cycles, when the number of clock cycles is above the maximum number of clock cycles, decreasing a frequency of a clock associated with the number of clock cycles, and when the number of clock cycles is below the minimum number of clock cycles increase the frequency of the clock.