Patent ID: 8730016

Claim:
A non-contact communication device comprising: an antenna having an antenna impedance and being configured to receive an AC signal having an input voltage and an input current, a main unit comprising a power-extraction unit having a charge pump and a communication unit including a main unit impedance, a tuning circuit, and a matching network for matching the antenna impedance to the main unit impedance and comprising a capacitor bank for providing a selectable capacitance, wherein the tuning circuit includes a passive phase detector for detecting a phase difference between the input voltage and the input current, and the passive phase detector being configured to respond to the input voltage and the input current by generating a quadrature phase error signal, the tuning circuit being configured to respond to the quadrature phase error signal by adjusting the impedance of the matching network in dependence on the phase difference so as to minimize quadrature phase error, by selecting the capacitance of the matching network.