Antenna Switch Embedded in Transmission Line Transformers of Differential PA and LNA

Abstract

An antenna switch embedded in the matching transmission line transformers (TLTs) of a differential power amplifier (PA) and LNA is presented, which selects the transmitter and receiver (Tx and Rx) in 5G communication systems. Because the switching function is implemented in the matching networks of a PA output and an LNA input, the chip size and insertion loss are reduced. A balun, an antenna switch, and matching networks of the PA and LNA are implemented simultaneously by carefully designing a three-port series-combining TLT with Tx and Rx switches. The measured insertion losses of Tx and Rx are 0.42 and 1.01 dB, respectively, at 28 GHz, and the isolation values of the Tx and Rx paths are 24.1 and 31.7 dB, respectively.