A phase-locked loop circuit ("PLL") is adjustable in both phase and
frequency. By providing a plurality of taps on the voltage-controlled
oscillator of the PLL, and providing separate multiplexers, each of which
can select a different tap--one for the PLL feedback loop and one for the
PLL output--one allows the user to adjust the phase of the output
relative to that of the input. Similarly, by providing loadable pre-scale
(divide by N), post-scale (divide by K) and feedback-scale (divide by M)
counters, one allows the user to adjust the frequency of the output to be
M/(NK) times that of the input.