A system incorporating and method of operating phase locked loop circuitry. In one embodiment, having programmable circuitry for adjustment of loop dynamics, a VCO has a first input terminal for selecting phase and frequency characteristics of an output signal and an output terminal on which the output signal is provided. A detector generates first VCO input signals indicative of phase and frequency differences between the VCO output signal and a reference signal. Circuitry digitizes the first VCO input signals and generates an integral path input signal therefrom. Slow integral path circuitry comprising, a first transistor device and a programmable low pass filter: receives the integral path input signal, and provides a low pass filtered version of the integral path input signal to control conduction through the first transistor device and provide a first adjustment signal for adjustment of the frequency of the VCO output signal.