| 摘要 |
A test structure for gathering switching history effect statistics includes a waveform generator circuit that selectively generates a first test waveform representative of a 1SW transistor switching event, and a second test waveform representative of a 2SW transistor switching event; and a history element circuit coupled to the waveform generator circuit, the history element circuit including a device under test (DUT) therein, and a variable delay chain therein, wherein a selected one of the first and second test waveforms are input to the DUT and the variable delay chain; wherein the history element circuit determines fractional a change in signal propagation delay through the DUT between the 1SW and 2SW transistor switching events, with the fractional change in signal propagation delay calibrated with timing measurements of a variable frequency ring oscillator; and wherein the test structure utilizes only external low-speed input and output signals with respect to a chip.
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