In a modern multi-core SoC, the Built-In Speed Grading (BISG) of each logic core is often necessary in order to ensure an adequate operating margin for accommodating all kinds of variation (e.g., PVT variation), and to guide the dynamic VDD tuning process as well. In general, a speed grading method for a logic core can be performed by repeating a specific delay test session, (e.g., built-in self-test with the latch-off capture scheme), with varying test clock frequencies to derive the maximum operating speed of a specific core under testing. In this paper, we propose an easy-to-use speed grading method featuring a wide-range synthesizable clock generation scheme so that it can support a logic core that could be used with different supply voltages and speeds in different application domains.