A programmable-load CMOS ring oscillator/inverter chain for propagation-delay measurements

A description is given of a test structure consisting of a combination of a ring oscillator and an inverter chain. The circuit can be used to carry out propagation delay measurements on two circuit types and under a number of load conditions. Full characterization only takes one test circuit. The elements of this structure are connected to a programmable load varying from a fan-in of 1 up to a fan-in of 15. In this way, the operating environment of the circuit can be simulated in hardware. The measurements can be carried out by means of a conventional automated digital measurement system providing AC and DC parametric measurement capabilities.<
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