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

Abstract

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 \left(\phi_{\text {ERR}}\right) detection gain of a subsampling phase detector (PD). Nevertheless, when SSPLLs operate in the W-band, the degradation of PN is unavoidable because the \phi_{\text {ERR}} detection gain decreases as the frequency of the VCO, f_{\text {vco}}, increases. As described at the left of Fig. 23.4.1, when the switch of the \mathrm{PD}, S W_{\mathrm{PD}}, is closed, the output of the \mathrm{PD}, S_{\mathrm{PD}}, should track the signal of the VCO, S_{\text {vco}}, closely. However, when f_{\text {vco}} increases to the W-band, the amplitude of S_{\mathrm{PD}} is reduced significantly by a parasitic pole that is present due to the turned-on resistance of S W_{\mathrm{PD}}, R_{\mathrm{ON}}, and the sampling capacitor, C_{\mathrm{S}} When S W_{\mathrm{PD}} is turned off, \phi_{\mathrm{ERR}} is detected in S_{\mathrm{PD}}, but its magnitude is already suppressed significantly relative to that in S_{\mathrm{vCO}}. This effect also can be interpreted in the frequency domain where S_{\text {vco}} is suppressed by a low-pass filter before the information of \phi_{\text {ERR}} is extracted at the baseband frequencies.