A novel electronically tunable active duplexer for wireless transceiver applications

In this paper, a novel electronically tunable active duplexer suitable for reconfigurable wireless transceiver applications is presented. The theory, design, and measured results of a varactor tunable active duplexer are summarized. The prototype active duplexer presented in this paper provides an electronically adjustable isolation of 20-50 dB between isolated ports and a gain of approximately 5 dB between coupled ports in the tunable range from 1.62 to 1.82 GHz in both transmit and receive modes of operations. The measured noise figure of the duplexer varied from 1.77 to 2.44 dB in the tuning range. The measured output powers at the 1-dB gain compression point and third-order intercept point, varied from 8.5 to 9.5 dBm and 20 to 29.5 dBm, respectively, in the tuning range. The design guidelines, measured S-parameters, and results of yield analysis of the duplexer are presented. The proposed duplexer can be implemented as a monolithic microwave integrated circuit