An 82fsrms-Jitter and 22.5mW-Power, 102GHz W-Band PLL Using a Power-Gating Injection-Locked Frequency-Multiplier- Based Phase Detector in 65nm CMOS

As the utilization of the mm-wave spectrum becomes active, designers' interests are shifting to even higher frequencies in the W-band. Given their potential use as carrier frequencies for the next-generation mobiles (i.e., beyond 5G), these W-band signals must have ultra-low phase noise (PN). Currently, the most popular solution to generate such frequencies is with a cascaded architecture: a first-stage PLL generates a low-PN signal at a relatively low frequency at which the VCO LC tank has a high Q factor, and following frequency multipliers (FMs) increase the frequency to the W-band [1]. Although various FMs have been proposed, all of them are limited in their ability to achieve a high multiplication factor, M. Push-push or harmonic-selection circuits have high conversion losses. Injection-locked FMs (ILFMs) require multiple stages due to their narrow lock ranges, which increase power consumption and complexity. Thus, single-stage direct PLLs [2-4] would be preferred if they could have a sufficiently wide loop bandwidth to suppress the poor PN of a W-band VCO. Subsampling PLLs (SSPLLs) are suitable for extending the bandwidth since they have low in-band PN due to the high phase-error (?? ERR ) detection gain of a subsampling phase detector (PD). Nevertheless, when SSPLLs operate in the W-band, the degradation of PN is unavoidable because the ?? ERR detection gain decreases as the frequency of the VCO, f VCO , increases. As described at the left of Fig. 23.4.1, when the switch of the PD, SWPD, is closed, the output of the PD, SPD, should track the signal of the VCO, S VCO , closely. However, when f VCO increases to the W-band, the amplitude of SPD is reduced significantly by a parasitic pole that is present due to the turned-on resistance of SW PD , R ON , and the sampling capacitor, CS. When SWPD is turned off, ?? ERR is detected in SPD, but its magnitude is already suppressed significantly relative to that in SVCO. This effect also can be interpreted in the frequency domain where S VCO is suppressed by a low-pass filter before the information of ?? ERR is extracted at the baseband frequencies