In accordance with an embodiment, a method includes: receiving, by an adjustable frequency doubling circuit, a first clock signal having a first clock frequency; using the adjustable frequency doubling circuit, generating a second clock signal having a second clock frequency that is twice the first clock frequency; measuring a duty cycle parameter of the second clock signal, where the duty cycle parameter is dependent on a duty cycle of the first clock signal or a duty cycle of the second clock signal; and using the adjustable frequency doubling circuit, adjusting the duty cycle of the first clock signal or the second clock signal based on the measuring.