Single-Chip Tri-Band WCDMA/HSDPA Transceiver without External SAW Filters and with Integrated TX Power Control

With growing WCDMA adoption there is a strong demand to reduce the cost of WCDMA terminals. Contributing to the relatively high WCDMA terminal cost is the low integration of today's WCDMA radios. Since WCDMA is an FDD system the transmitter and receiver are on simultaneously. A duplexer is used to isolate the receiver from the transmit signal but the isolation of small low-cost duplexers is limited, with a guaranteed isolation at the TX frequency of not more than 52dB. For a Class-3 terminal with 2dB TX path loss due to duplexer and switch, the power at the PA output is +26dBm and the receiver will see a TX leakage of up to -26dBm. Today's state-of- the-art WCDMA transceivers deal with the TX blocking problem by using an external TX SAW filter to eliminate TX noise in the RX band and an external LNA and RX SAW filter to achieve sufficient RX linearity. A typical tri-band transceiver requires 6 SAW filters and 3 LNAs. The tri-band WCDMA transceiver presented here eliminates all external SAW filters and LNAs and achieves excellent performance with standard low-cost duplexers.