An electrosurgical generator includes one or more radio frequency (RF) power sources and an output stage including at least two output lines for connection to an electrosurgical instrument. The generator includes means for measuring a parameter associated with the electrosurgical procedure, such as the impedance measured across two of the output lines. A controller controls the generator such that it delivers a first RF waveform (such as a cutting signal) or a second RF waveform (such as a coagulating signal) to the output lines, and, in a combined mode, both first and second waveforms. The controller automatically adjusts at least one aspect of one or both waveforms in the combined mode, in response to the measured parameter associated with the surgical procedure.