Abstract: Circuitry for determining timing characteristics, for example, access time, setup time, hold time, recovery time and removal time, of as-manufactured digital circuit elements, such as latches, flip-flops and memory cells. Each element under test is embodied in variable-loop-path ring oscillator circuitry that includes multiple ring-oscillator loop paths, each of which differs from the other(s) in terms of inclusion and exclusion of ones of a data input and a data output of the element under test. Each loop path is caused to oscillate at each of a plurality of frequencies, and data regarding the oscillation frequencies is used to determine one or more timing characteristics of the element under test. The variable-loop-path ring oscillator circuitry can be incorporated into a variety of test systems, including automated testing equipment, and built-in self test structures and can be used in performing model-to-hardware correlation of library cells that include testable as-manufactured digital circuit elements.

Abstract: Circuitry for determining timing characteristics, for example, access time, setup time, hold time, recovery time and removal time, of as-manufactured digital circuit elements, such as latches, flip-flops and memory cells. Each element under test is embodied in variable-loop-path ring oscillator circuitry that includes multiple ring-oscillator loop paths, each of which differs from the other(s) in terms of inclusion and exclusion of ones of a data input and a data output of the element under test. Each loop path is caused to oscillate at each of a plurality of frequencies, and data regarding the oscillation frequencies is used to determine one or more timing characteristics of the element under test. The variable-loop-path ring oscillator circuitry can be incorporated into a variety of test systems, including automated testing equipment, and built-in self test structures and can be used in performing model-to-hardware correlation of library cells that include testable as-manufactured digital circuit elements.

Abstract: A structure and associated method to allow an oscillator circuit to operate with a plurality of different crystals. The oscillator circuit comprises a semiconductor device and a crystal. The semiconductor device comprises a primary inverting amplifier and a crystal substitution damping resistor. The crystal is electrically coupled to the primary inverting amplifier. A resistance value of the crystal substitution resistor is adapted to vary in order to control an amount of current flow from the primary inverting amplifier to the crystal. The amount of the current flow to the crystal is dependent upon an electrical property of the crystal.