An integrated circuit includes phase locked loop (PLL) circuitry, voltage controlled oscillator (VCO) circuitry, and interface circuitry. The PLL circuitry includes a reference signal input terminal, a reference frequency divider circuit, a reference signal output terminal, a switch, a phase detector, a charge pump, and a control voltage output terminal. The reference frequency divider circuit is coupled to the reference signal input terminal. The switch is coupled to the reference frequency divider circuit and to the reference signal output terminal. The switch is configured to switchably connect the reference frequency divider circuit to the reference signal output terminal. The VCO circuitry includes a control voltage input terminal, a VCO, calibration circuitry, and a calibration input/output (I/O) terminal. The VCO is coupled to the control voltage input terminal. The calibration circuitry is coupled to the VCO. The calibration I/O terminal is coupled to the calibration circuitry.