Patent ID: 6963257

Claim:
A duplexer for use in a communication device, the communication device having an antenna for conveying communication signals; a transmit path operatively connected to the antenna for transmitting the signals; and a receive path operatively connected to the antenna for receiving the signals, said duplexer comprising: a first coupled resonator device disposed in the transmit path for filtering the signals in the transmit path; a second coupled resonator device disposed in the receive path for filtering the signals in the receive path; and a phase shifter disposed in the receive path and operatively connected to the second coupled resonator device, wherein each of said first and second coupled resonator devices comprises: an input end for receiving the signals in the corresponding path, and an output end for providing filtered signals in the corresponding path; a first resonator operatively connected to the input end to provide acoustic wave signals indicative of the received signals; a first delay section, responsive to the acoustic wave signals, for providing delayed acoustic wave signals; an intermediate resonator having a first end and a second end, responsive to the delayed acoustic wave signals at the first end, for producing at the first and second ends electric signals indicative of the delayed acoustic wave signals for generating further acoustic wave signals at the second end; a second delay section, responsive to the further acoustic wave signals, for providing further delayed acoustic wave signals, the second delay section spaced from the first delay section; and a second resonator operatively connected to the output end, for providing the filtered signals to the output end responsive to the further delayed acoustic wave signals.