Diplexer separates two different frequency bands in the receive path and combines them in the transmit path, with bands being widely separated, such as separating GSM and WCDMA. Duplexer uses a single antenna for both transmit and receive simultaneously for bands closer together, such as uplink and downlink DCS. Duplexers have higher Tx-Rx isolation around 90-95 dB and use bandpass filters or switching to separate transmit and receive signals on the same channel.