A 65nm CMOS wideband TDD front-end with integrated T/R switching via PA re-use

Abstract

A wideband time-division duplex (TDD) front-end with an integrated transmit/receive (T/R) switching technique is implemented in 65nm CMOS. By re-using the PA as an LNA during receive mode, the system eliminates the conventional series T/R switch from the signal path and utilizes only DC mode control switches to enable TDD co-existence. With integrated front-end balun transformer, the full polar transmitter achieves 20dBm peak output power with 32.7% peak drain efficiency. In receive mode, the PA is reconfigured into a wideband 3.4GHz-5.4GHz LNA achieving -6.7dBm P1dB and 5.1dB NF.