Patent ID: 7308024

Claim:
A cordless communication device having a handset unit and a base unit, comprising: a transceiver, disposed in the handset unit, having a transmitter and a receiver, wherein the handset unit transceiver includes: at least one intermediate frequency (IF) filter adapted to filter a received audio signal to output an IF signal corresponding to the received audio signal; a quadrature detector adapted to input the IF signal and to output a base band signal corresponding to the received audio signal, the base band signal being a composite of a sinusoid with an overlay of a pulse amplitude modulated (PAM) signal including the received audio signal chopped at a predetermined frequency; a high pass filter adapted to filter the base band signal to output a square wave pulse train identical to the PAM signal; and a ringing oscillator adapted to generate a switching signal in synchronization with the square wave pulse train and to generate a 180 degrees out-of-phase version of the switching signal, wherein the transmitter is turned on and off at a predetermined frequency by the switching signal and the receiver is turned on and off by the 180 degrees out-of-phase version of the switching signal, to ensure than the receiver is turned off when the transmitter is turned on.