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

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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.34\times 0.98$ </tex-math></inline-formula> mm2.