A transmitter has a signal generator, an amplifier, a detection circuit, a comparison circuit, a loop filter, and an adjustable clock. The signal generator produces a signal. The signal is produced with a first frequency characteristic and contains frequency-related information. The detection circuit detects the first frequency-related characteristic and generates an associated signal in response. A comparison circuit compares the signal from the detection circuit and another signal. It outputs a signal associated with the difference between the two. A loop filter receives the output of the comparison circuit and generates a signal to the signal generator in. The loop filter is clocked at a second frequency by a signal from a clock circuit. The clock circuit can compare the first frequency and the second frequency, and can change the second frequency based upon a relationship between the two frequencies.