A radio frequency ablation system, includes a single frequency RF signal generator, control circuitry configured to set phases and amplitudes of a plurality of replicas of the RF signal, a plurality of non-linear amplifiers, configured to amplify the plurality of replicas of the RF signal, and to drive a respective plurality of ablation electrodes in a patient body with the amplified replicas. A processor is configured to receive a superposition of the plurality of replicas as a return signal from a body surface patch electrode, and to adaptively adjust phases and amplitudes of the amplified replicas in response to the return signal with the control circuitry to zero crosstalk currents. In a tissue contact check mode of operation the phases of the amplified replicas are identical, and in an ablation mode of operation the phases of the amplified replicas differ from one another.
