An apparatus includes a first circuit, a second circuit, and a capacitor. The first circuit includes a sense element. The capacitor couples the first circuit to the second circuit. The first feedback path couples the second circuit to the first circuit. And the second feedback path couples the second circuit to the first circuit. A method includes generating, for an oscillator signal having an amplitude and a gain, a substantially direct current signal related to an amplitude, and controlling the gain with the substantially direct current signal.