Efficient Wideband mmW Transceiver Front End for 5G Base Stations in 22-nm FD-SOI CMOS

Abstract

This article presents a fully integrated millimeter-wave (mmW) transceiver front end covering 24.25–29.5 GHz. It features a wideband Doherty power amplifier utilizing adaptive bias and a transmit/receive switch (TRX-switch) that has embedded low noise amplifier to antenna matching. The phase shift of 90° to the Doherty auxiliary amplifier is achieved using a separate IQ-mixer with rearranged phases in the auxiliary path, ensuring a wideband 90° phase shift, and avoiding 3-dB loss from radio frequency (RF) input power splitting. Special emphasis is on the analysis of adaptive bias, the Doherty output combiner network, the decoupling capacitors, and the TRX-switch. Including TRX-switch losses of 1.1 dB in transmit mode, the transmitter reaches a saturated output power of 18.3 dBm with a 1-dB output compression point of 15.9 dBm. Stimulated with a 400-MHz 16-QAM orthogonal frequency-division multiplexing (OFDM) IQ-signal at baseband, without digital IQ-compensation and predistortion, the transmitter delivers a 26.5-GHz modulated signal with an output power ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$P_{\mathrm{ out}}$ </tex-math></inline-formula> ) of 12.8 dBm and an error vector magnitude (EVM) of -20.2 dB. The complete transmitter, including quadrature local oscillator drivers, then achieves a power added efficiency (PAE) of 5.8%. For a 1600-MHz wide 64-QAM OFDM signal, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$P_{\mathrm{ out}}$ </tex-math></inline-formula> is 9.0 dBm, with an EVM <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$=\,\,-$ </tex-math></inline-formula> 23.3 dB and a complete transmitter PAE of 3.2%. In receive mode including TRX-switch, at 27.25 GHz, the noise figure is below 4 dB with a gain of 23 dB and a third-order input-referred intercept point of -9 dBm. The active part of the die, manufactured in 22-nm fully depleted silicon on insulator (FD-SOI) CMOS, occupies 2.3 mm2.

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