Exemplary embodiments are directed to wireless power transfer. A receiver with a receive antenna couples with near field radiation in a coupling-mode region. The receiver generates an RF signal at a resonant frequency responsive to the near field radiation. A de-tuning circuit generates a variable impedance responsive to a control signal to modify the RF signal to a smaller amplitude or to a different resonant frequency. A rectifier converts the modified RF signal to a DC signal. A comparator creates a feedback loop by generating the control signal responsive to comparing the DC signal to a reference voltage. The de-tuning circuit may operate in digital mode or in linear mode with the feedback. An impedance element may be coupled to the de-tuning circuit to generate a voltage proportional to a current through the de-tuning circuit. The proportional voltage is rectified to a receive signal with information sent from a transmitter.