Pourakbar, Mohammadreza (2016) A tunable low-isolation device for adaptive duplexers. PhD thesis, Victoria University.

Abstract

Today's fourth generation (4G) long term evolution (LTE) handsets using frequency division duplex operate on two frequencies to provide simultaneous transmission and reception. A duplexer isolates the sensitive receiver (Rx) circuits from the high-power transmitter (Tx) output. The classical duplexer relies on two highly selective filters using surface acoustic wave or thin film bulk acoustic resonator technology. One is placed in the transmitter path to attenuate the Tx noise in the Rx band and another is placed in the receiver path to prevent the large Tx leakage signal from overloading the receiver. These filters have low insertion loss and high linearity, but support only one frequency band, are bulky and cannot be integrated into the receiver microcircuit. A set of duplexers connected to the antenna through an antenna switch is therefore required for multi-band operation, handicapping the radio handset in terms of cost and size. The lack of a tunable duplexer alternative is a major drawback. The current research trend is to make the duplexer frequency agile, adaptive and integrable. In this thesis, single-band and multi-band integrated solutions of a low-isolation device (LID) are proposed to provide the initial isolation for an adaptive duplexer scheme employing cancelling loops.

Search Google Scholar

Repository staff login