US Patent 11923853 Circuit structures to measure flip-flop timing characteristics

A ring oscillator circuit with a frequency that is sensitive to the timing of a clock-to-Q (clk2Q) propagation delay of one or more flip-flops utilized in the ring oscillator. The clock2Q is the delay between the clock signal arriving at the clock pin on the flop and the Q output reflecting the state of the input data signal to the flop. Clk2q delay measurements are made based on measurement of the ring oscillator frequency, leading to more accurate estimates of clk2Q for different types of flip-flops and flip-flop combinations, which may in turn enable improvements in circuit layouts, performance, and area.