Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for dynamically tuning circuit elements. One aspect includes a variable capacitance device. The device includes a first capacitor, a first switch, a second capacitor, a second switch, and control circuitry. The control circuitry is configured to adjust respective capacitances of the first and second capacitors by causing a first control signal to be applied to the first-switch control terminal for a duration of time in response to detecting a zero voltage condition across the first switch, and by causing a second control signal to be applied to the second-switch control terminal for the duration of time in response to detecting a zero voltage condition across the second switch.