An impedance matching network includes a first input port that receives radio frequency (RF) power and includes an input impedance, an output port that provides the RF power and includes an output impedance, and a variable capacitance module that varies the output impedance. The variable capacitance module includes a first variable capacitor, a second variable capacitor, a first motor, and a second motor that adjusts a capacitance of the second variable capacitor. A relationship between a desired value of the capacitance and an actual value of the capacitance is dependent on a capacitance of the first variable capacitor.