A 28-nm FD-SOI 115-fs Jitter PLL-Based LO System for 24-30-GHz Sliding-IF 5G Transceivers

A system for local oscillator (LO) signal generation in 5G millimeter-wave (mmW) multi-antenna transceivers is presented. The system is modular with one phase locked loop (PLL) per antenna element transceiver, and a test circuit implemented in 28-nm fully depleted silicon on insulator (FD-SOI) CMOS features two such PLLs and a 491.52 MHz crystal oscillator (XO) generating a common frequency reference. A fractional-N architecture is employed to achieve high-frequency resolution, and the quantization noise is reduced using a novel frequency divider, which achieves full integer resolution while still using a pre-scaler. The system covers the 3rd Generation Partnership Project (3GPP) bands n257 and n258, achieved by a digital coarse tuning of the voltage-controlled oscillator (VCO). The chip area of each PLL is 0.11 mm(2), and 0.029 mm(2) for the XO. The total power consumption of the system is 35 mW, where each PLL consumes 15.4 mW and the XO consumes 0.84 mW. The total rms jitter from 20-kHz to 500-MHz offset for a 26-GHz carrier is just 115 fs, corresponding to an FOMj of -244 dB, which is the best reported figure for a fractional-N PLL above 15 GHz. The error-vector magnitude (EVM) due to phase noise is -34.6 dBc using an orthogonal frequency-division multiplexing (OFDM) signal with 120-kHz sub-carrier spacing, sufficient to support 256 QAM.