An Electrical Balance Duplexer Architecture Without Inherent Insertion Loss Limitation

Current surface acoustic wave based duplexers have the drawback of fixed frequency response, leading to complex RF front ends with a high amount of duplexers and switches. New approaches for tunable duplexers such as electrical balance duplexers (EBD) have the drawback of limited insertion loss or the need of active components which introduce noise. In this work we present a variation of the electrical balance duplexer overcoming this fundamental 3 dB insertion loss limitation for frequency division duplex (FDD) applications. The measurements showed an insertion loss smaller 3 dB for a varactor based realization.