US Patent 7479810 Slew-rate detection circuit using switched-capacitor comparators

In general, in one aspect, the disclosure describes an apparatus that includes a first switched capacitor comparator to be charged to a first reference voltage and to compare an input signal to the first reference voltage and to generate a first output signal when the input signal reaches the first reference voltage. A second switched capacitor comparator to be charged to a second reference voltage and to compare the input signal to the second reference voltage and to generate a second output signal when the input signal reaches the second reference voltage. Time between the first output signal and the second output signal is slew rate of the input signal.