A 23.5-28.5 GHz High-Gain CMOS Transceiver Based on LO Phase-Shifting Architecture With Broadband LO/IF for 5G Communications

This paper presents a high-flexibility and low-cost transceiver (TRX) in 65-nm CMOS process for fifth-generation (5G) communications. The TRX is based on local-oscillator (LO) phase-shifting architecture with 5 bits of gain control and 6 bits of phase control. To enhance the transceiver gain, bandwidth, efficiency, noise performance, and achieve ultra-low amplitude and phase errors without any calibration, a variety of innovative techniques are introduced in this work. The TX path demonstrates a measured peak conversion gain (CG) of 43.1 dB with the IF fractional bandwidth of 79% from 3.5 to 8.1 GHz and the RF of20% from 23.4 to 28.5 GHz. The measured TX OP1dB is up to 13.3 dBm at26 GHz. In the RX mode, the measured peak CG is 29.6 dB with 134% fractional bandwidth of the IF (2.1 to 10.6 GHz), 19% of the RF (23.7 to 28.6 GHz) and the minimum noise Figure is 5.5 dB (including T/R switch). Moreover, the TRX with 6-bit phase resolution realizes a measured RMS amplitude and phase errors of less than 0.63 dB and 2. 4°, respectively. The proposed wideband transceiver simultaneously implements broadband RF/LO/IF while maintaining ultra-low gain and phase errors without any calibration. Such a system with only one chip can meet the requirements of IF, LO and RE frequency combinations of different scenarios, which is suitable for high data-rate and low cost 5G applications.

I. Introduction

The fifth-generation (5G) communication systems at millimeter-wave (mm-wave) frequencies are being actively developed which meet the demand of high-speed and low-latency data links [1]–[3]. Within the frequency range 2 (FR2) defined in the 5G new radio (NR) standard, there are different frequency bands have been allocated worldwide to 5G mm-wave wireless communication systems, including n257 band (26.5-29.5 GHz), n258 band (24.25-27.50 GHz), and n261 band (27.5-28.35 GHz) [4]. To improve the equivalent isotropic radiated power (EIRP) and signal-to-noise ratio (SNR) of transceivers at mm-wave bands, 5G communication links will rely on directive communications using phased-array techniques to overcome high free-space path loss (FSPL) [5]–[8]. Based on above-mentioned, the cost and size of phased-arrays need to be significantly lowered for massive use, which indicates the designed phased-array beamformer chips should not only can operate over a wider band so as to allow multi-standard operation, but also require the low noise amplifier (LNA), power amplifier (PA), switches, phase shifters (PSs), variable gain amplifiers (VGAs), up/downconverters integrated together on a single chip.