Multi-switch-controlled multi-mode TRFE with a high-linearity ATRSW for 2.4-GHz ISM applications

This paper presents a multi-switch-controlled multi-mode transceiver front end (TRFE) designed for the 2.4-GHz industrial–scientific–medical (ISM) band, with a particular focus on enhancing the linearity of the transmit/receive switch (TRSW) on the antenna side. Considering the distinct power levels in the RX/TX paths, the TRSW is designed to be asymmetric. This design not only elevates IP_-0.1dB by over 50 % compared to the conventional symmetric topology, but also absorbing its function into the input matching network (IMN) of the low noise amplifier (LNA), thereby minimally impacting the noise figure (NF) of the RX chain. For the TX path, the high-pass component of the power amplifier (PA) output matching network (OMN) is repurposed, with a singular inductor being redeployed to serve as an inductive ESD safeguard. Moreover, the driving stage employs a passive gain-boosting technique, which elevates the gain by 3 dB compared to the traditional cascode structure. For verification, this TRFE is fabricated in 0.18-μm CMOS with a die size of 1.53 mm². It achieves a NF of 2.4 dB and a RX gain of 16.7 dB under a 3.3-V supply. A TX gain of 26.2 dB and a saturation output power of 23.3 dBm with a peak power-added efficiency (PAE) of 38.8 % are also demonstrated.