An integrated circuit comprises a microelectromechanical (MEMS) resonator circuit that generates a reference frequency and that includes a semiconductor oscillator that generates resonator drive signal having a drive frequency and a MEMS resonator that receives the resonator drive signal. A temperature sensor senses a temperature of the integrated circuit. Memory stores calibration parameters and selects at least one of the calibration parameters as a function of the sensed temperature, wherein the drive frequency is based on the calibration parameters.