A Compact RF Module With Hybrid Stacked Transformer and Integrated Transceiver Switch in 65 nm CMOS Technology

Yuting Chen, Qing Guo, Yue Ma, Xingang Ren, Bo Wu, Gang Wang, Xianliang Wu

Abstract: In this brief, we propose an RF module that integrates a Doherty power amplifier (PA), a low noise amplifier (LNA), and a transceiver (TRX) switch. This configuration enables transmitter (TX) and receiver (RX) mode conversion using a single MOSFET as a switch and a hybrid stacked transformer (HSTF) that covers just 0.0182 mm2. The HSTF co-designs the output matching network (OMN) of the Doherty PA and the input matching network (IMN) of the LNA, thereby reducing insertion loss and significantly miniaturizing the RF front-end. The introduction of an adjustable capacitor bank helps in regulating the parasitic capacitance generated by different operating modes in the HSTF. The 35–41 GHz TRX front-end is implemented in a 65 nm CMOS (1P9M) process. In the TX mode, the high saturated output power (Psat), 1-dB output compression point (OP1dB) and peak power added efficiency (PAE) are measured as 18.6 dBm, 17.7 dBm, and 25.8% at 38 GHz, respectively. The measured PAE at 6-dB and 9-dB power back-off (PBO) efficiency are 18.3% and 13.7%, resulting in efficiency enhancement ratios of 1.46 and 1.51 when compared with an ideal class-B PA. In the RX mode, the minimum noise figure (NF) is 4.8 dB at 38 GHz. The overall chip size of the TRX, including the three-stage PA/LNA and I/O pads, is approximately $1.34\times 0.98$ mm2.