RF CMOS Duplexers for Frequency-Division Duplex Radios: The Most Recent Developments

One main challenge for modern mobile communication systems is simultaneous demand for higher data rates (performance) and lower power consumption and size (cost). One way to increase wireless data transfer capacity is to employ frequency-division duplex (FDD) wireless systems where both transmitter (Tx) and receiver (Rx) work at the same time but in two different frequency bands with sufficient amount of guard band between them. An FDD system requires sharing the antenna between Tx and Rx [
Figure 1(a)
]. Because of the simultaneous operation of Tx and Rx units, modern FDD front-end realizations face numerous challenges, as shown in
Figure 1(b)
: