A voltage controlled oscillator includes a plurality of serially connected composite gain stages. A composite gain stage includes a transconductance stage and a transimpedance stage. The transconductance stage has first and second current paths from a first power supply voltage terminal to a second power supply voltage terminal. A first variable resistance is coupled between the first and second current paths. The transimpedance stage has a first inverter and a second inverter. The first inverter has an input terminal coupled to the output of the first current path and an output terminal. The second inverter has an input terminal coupled to the output of the second current path, and an output terminal. A second variable resistance is coupled between the input terminal and the output terminal of the first inverter, and a third variable resistance is coupled between the input terminal and the output terminal of the second inverter.