Dead zone-less low power phase frequency detector, independent of duty cycle variations for charge pump phase locked loop

In phase frequency detector (PFD) phase characteristics, the presence of dead zone fails to turn on the charge pump (CP) of the phase locked loop (PLL). This degrades the phase noise in PLL. To overcome this drawback in PFD, a circuit to eliminate dead zone using pass transistor logic (PTL) and delay cells (DCs) is proposed in this paper. The proposed circuit has been implemented in UMC 0.18 μm\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\upmu \mathrm{m}$$\end{document} CMOS process and simulated in a cadence spectre environment. From the post layout simulation results, it is noted that for a phase difference of -π\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$- \pi$$\end{document} to +π\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$+ \pi$$\end{document}, the PFD achieves 100% linearity and is free from the dead zone. The designed PFD consumes power of 28.8 μ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\upmu$$\end{document}W at an operating frequency of 100 MHz. The proposed PFD is also verified across process voltage temperature (PVT) variations for its linearity. The PFD is independent of duty cycle variations of its input clock signals. It occupies an area of 312.4 μm2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\upmu \mathrm{m}^{2}$$\end{document}.