A device including a voltage regulator with an adaptive switching frequency circuit for noise-sensitive analog circuits, such as oscillatory systems with phase-lock loops (PLLs) and voltage-controlled oscillators (VCOs) is described. In an exemplary embodiment, the device includes a reference clock oscillator, a low-jitter oscillator, a power supply including a clock signal input to regulate a power supply voltage for the low-jitter oscillator, a clock detector to generate a clock detector control signal when the low-jitter oscillator output frequency is stable, and a multiplexer to select between a reference clock oscillator output signal and a low-jitter oscillator output signal as the clock signal input to the power supply to mitigate effects of period jitter in the low-jitter oscillator output signal when the clock detector control signal is asserted. In a further exemplary embodiment, a clock detector control signal is configured to control the multiplexer to select the low-jitter oscillator output signal as the clock signal input to the power supply when the low-jitter oscillator output frequency is stable.