A first radio frequency (RF) generator includes a first RF power source that generates an RF power output. A first sensor generates at least one sensor signal based on the RF power output. A first signal processing unit generates magnitude and phase signals associated with the at least one sensor signal. A second signal processing unit generates a first control signal to control a frequency and a phase of the first RF power source based on the magnitude and phase signals. The first RF power source determines, based on the magnitude signals, whether to generate the RF power output in response to the first control signal or in response to a second control signal received from a second RF generator.