Patent ID: 7190933

Claim:
A transceiver circuit having a transmitter circuit, a receiver circuit, and an automatic tuning circuit, where the transmitter circuit includes a power amplifier and where the automatic tuning circuit comprises: a capacitance bank coupled between the power amplifier and a package connection for connecting to a resonant circuit that includes an antenna, the capacitance bank having an input that is coupled to an output of the power amplifier, an output that is coupled to the resonant circuit, and a control input, where a capacitance of the capacitance bank is determined by a control word received at the control input; and a tuning circuit having a first input for receiving a first voltage present at the inputs of the power amplifier, a second input for receiving a second voltage present across the capacitance bank, a mode input for receiving a mode signal, and an output for generating the control word responsive to the first and second voltages, where the tuning circuit is further configured to hold constant the value of the control word responsive to the mode signal, where the mode signal corresponds to a receive mode.