Peak detection in a near field communicator to provide reliable measurement of amplitude of a RF signal for accurate demodulation and regulation

摘要

A near field communicator has an inductive coupler or antenna 50, for coupling to a RF H-field produced by another near field communicator to provide an induced RF voltage AC1-AC2. A peak detector 52 is coupled to receive the RF voltage from the inductive coupler 50 and senses a change in polarity of the received RF voltage. The peak detector 52 provides an output signal 56 based on the received RF voltage after a delay (65, 67 fig.3a) following the sensed changed in polarity (63 fig.3a). Additionally, the peak detector 52 may control a voltage controlled impedance to couple the voltage to an output of the peak detector 52 in response to the sensed change in polarity of the voltage. Furthermore, the near field communicator may provide a delayed control signal to a pulse generator (69, 71 fig.3a) in dependence upon the inductively coupled voltage and the pulse generator (69, 71 fig.3a) causes the voltage to be coupled to a voltage regulator.