An Ultra-Low Integrated-Phase-Noise 28-GHz LO Generator for 5G Transceivers Supporting Multiple Frequency Bands

This work presents a multi-band LO generator that concurrently can support existing cellular bands below 6 GHz and new millimeter-wave (mmW) bands for 5G. Using a low-noise reference-frequency doubler, a $\Delta \Sigma$ fractional-N phase-locked loop (PLL) generates GHz-range signals with low integrated phase noise (IPN). Then, injection-locked frequency multipliers increase these frequencies to mmW bands without degrading IPN. The proposed LO-generator was fabricated in a 65-nm CMOS process. When the PLL is in the fractional-N mode, the measured IPN and RMS jitter integrated from 1 kHz to 100 MHz of the 29.23-GHz signal were −31.4 dBc and 206 fs, respectively. When the PLL is in the integer-N mode, the measured IPN and RMS jitter of the 28.8-GHz signal were −33.1 dBc and 172 fs, respectively. The silicon area was 0.95 mm$^{\mathbf{2}}$, and the total power consumption was 36.4 mW.