摘要
Built-in speed grading (BISG) is a technique that measures the maximum operating speed ( F-max) of a circuit under grading (CUG) in silicon. Recently, it has been reported as an effective aging sensor as well. In nowadays-chiplet-based design, the BISG circuit and the CUG could use different process technologies. In general, the BISG circuit needs to produce a clock signal with a frequency matching the F-max of the CUG. In this article, we discuss how to leverage an existing flexible wide-range cell-based phased-locked loop (PLL) with a frequency doubling circuit (FDC) to support even higher F-max for a CUG that may use a more advanced technology in another die. As demonstrated in a 90 nm process, a PLL supporting a frequency range of 40 MHz, 1.25 GHz using a mature 90 nm CMOS process can now support up to 2 GHz.