A frequency measuring circuit may include an edge detector, a charge pump, and an analog-to-digital (A/D) converter. The edge detector may be configured to generate an output pulse responsive to an edge of an input clock signal. The charge pump may be configured to generate an output signal responsive to the output pulse from the edge detector. The analog-to-digital (A/D) converter may be configured to convert the output signal into a digital value representing a frequency of the input clock signal. Related methods and integrated circuit memory devices are also discussed.