Row circuit ring oscillator method for evaluating memory cell performance
First Claim
1. A method for measuring characteristics of a memory array, said method comprising:
- enabling a cascade of memory cells of a particular row of said memory array, wherein said memory cells form a ring oscillator having a frequency dependent on a loading provided by other rows of memory cells in said memory array;
measuring a frequency of oscillation of said ring oscillator in order to determine a characteristic of said memory array; and
adjusting a leakage present at outputs of said memory cell by changing a state of said other memory cells within said memory array, and wherein said measuring is performed for multiple leakage states selected by said adjusting, whereby said method determines an effect of said leakage on said frequency.
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Accused Products
Abstract
A method for evaluating memory cell performance provides for circuit delay and performance measurements in an actual memory circuit environment. A ring oscillator implemented in a row of memory cells and having outputs connected to one or more bitlines along with other memory cells that are substantially identical to the ring oscillator cells is operated by the method. Logic may be included for providing a fully functional memory array, so that the cells other than the ring oscillator cells can be used for storage when the ring oscillator row wordlines are disabled. One or both power supply rails of individual cross-coupled inverter stages forming static memory cells used in the ring oscillator circuit may be isolated from each other in order to introduce a voltage asymmetry so that circuit asymmetry effects on delay can be evaluated.
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Citations
12 Claims
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1. A method for measuring characteristics of a memory array, said method comprising:
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enabling a cascade of memory cells of a particular row of said memory array, wherein said memory cells form a ring oscillator having a frequency dependent on a loading provided by other rows of memory cells in said memory array; measuring a frequency of oscillation of said ring oscillator in order to determine a characteristic of said memory array; and adjusting a leakage present at outputs of said memory cell by changing a state of said other memory cells within said memory array, and wherein said measuring is performed for multiple leakage states selected by said adjusting, whereby said method determines an effect of said leakage on said frequency. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for measuring characteristics of a memory array, said method comprising:
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enabling a cascade of memory cells of a particular row of said memory array, wherein said memory cells form a ring oscillator having a frequency dependent on a loading provided by other rows of memory cells in said memory array; and measuring a frequency of oscillation of said ring oscillator in order to determine a characteristic of said memory array, and wherein said enabling is performed by providing a connection between an output of a given sense amplifier having at least one input connected to a corresponding given bitline of said memory array and a next bitline of said memory array, and enabling an output of said sense amplifier onto said next bitline, whereby a state change at each bitline is propagated to said next bitline through said sense amplifier of said given row and said particular memory cell corresponding to said next column member of said particular row. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification