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US 6,426,641 B1Granted
Single pin performance screen ring oscillator with frequency division
AssigneeInternational Business Machines Corporation
InventorsSteven P. Koch, Donald L. Wheater, Larry Wissel
Life of this patent
Estimating the term…
Abstract
An oscillator circuit on a chip with a single I/O node whose output generally corresponds to a performance level of the IC chip. The single I/O node provides an easy access and testing point for evaluating chip performance. The I/O node is used for coupling to the oscillator circuit, and for activating and monitoring its oscillating output signal. The single I/O node may be accessed at the wafer level, after packaging, or in the field.
Claims6
Apparatus comprising:
- an IC chip;
- a pad on IC chip;
- an oscillator circuit manufactured on the IC chip, the oscillator circuit comprising:
- an oscillator having a first input and a first output;
- only one I/O point connected to the pad for receiving an activation signal which starts the oscillator, and for outputting an oscillating signal having a frequency generated by the started oscillator;
- and
- a first inverter having a second input coupled to the I/O point and a second output coupled to the first input of the oscillator, and a buffer having a third input coupled to the first output of the oscillator and a third output coupled to the I/O point, wherein the first inverter and the buffer isolate the oscillator from the I/O point after the oscillator is started to maintain the frequency of the oscillating signal independent of loading on the I/O point,
- further wherein the frequency of the oscillating signal is monitored in order to determine whether the frequency falls within a predetermined performance window.
5 more elements
An IC chip testing system comprising:
- an IC chip;
- a contact pad on the IC chip;
- an oscillator circuit manufactured on the IC chip, the oscillator circuit comprising:
- an oscillator having an input and an output;
- only one I/O node connected to the contact pad for receiving an activation signal which starts the oscillator, and for outputting an oscillating signal having a frequency generated by the started oscillator;
- and
- a first inverter coupled to the one I/O node and the input of the oscillator, and a buffer coupled to the output of the oscillator and the one I/O node, wherein the first inverter and the buffer isolate the oscillator from loading effects induced upon the one I/O node after the one I/O node receives the activation signal so that the frequency of the oscillating signal is thereafter independent of loading on the one I/O point.
4 more elements
A method of testing an IC chip, comprising:
- manufacturing an oscillator circuit on the IC chip, wherein the oscillator circuit comprises an oscillator having an input and an output, only one I/O point, a first inverter and a buffer;
- providing a contact pad on the IC chip that is connected to the only one I/O point;
- coupling a probe to the pad, including inducing an activation voltage on the pad with the probe for starting the oscillator circuit oscillating and maintaining contact between the probe and the pad;
- the probe receiving an oscillating signal having a frequency from the started oscillator circuit through the pad via the only one I/O point;
- the first inverter coupled to the one I/O point and the input of the oscillator, and the buffer coupled to the output of the oscillator and the one I/O point, wherein the first inverter and the buffer isolate the oscillator from the one I/O point after the oscillator is started for maintaining the frequency of the oscillating signal independent of loading on the one I/O point, and
- measuring the frequency of the oscillating signal.
3 more elements
Dependencies are inferred from the claim text.