Measuring internal signals of an integrated circuit
First Claim
1. A method for testing an integrated circuit, the method comprising:
- generating a plurality of internal signals within the integrated circuit (IC);
selecting a first internal signal from the plurality of internal signals in response to a command from an external test station;
coupling the first internal signal to a first external pin of the IC either directly or via a buffer circuit located within the IC in response to a command from the external test station; and
measuring the first internal signal by the external test station by monitoring the first external pin of the IC to produce a measured value;
further including calibrating the buffer circuit by;
providing a known calibration signal to a second external pin of the IC;
coupling the known calibration signal to the first external pin of the IC via the buffer circuit in response to a command from the external test station; and
measuring the known calibration signal after it is buffered by monitoring the first external pin of the IC by the external test station to produce a calibration value.
1 Assignment
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Accused Products
Abstract
An integrated circuit (IC) is provided with functional logic having a plurality of internal signal lines and test logic. The test logic has a plurality of inputs coupled to the plurality of internal signal lines and with an output coupled to a first external pin of the integrated circuit. The test logic includes a buffer, and the test logic is configured to selectively couple each of the signals received on the plurality of signal lines either directly or via the buffer to the first external pin of the IC. The test logic is configured to selectively couple a signal received on a second external pin of the IC either via the buffer to the first external pin of the IC in order to calibrate the buffer.
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Citations
7 Claims
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1. A method for testing an integrated circuit, the method comprising:
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generating a plurality of internal signals within the integrated circuit (IC); selecting a first internal signal from the plurality of internal signals in response to a command from an external test station; coupling the first internal signal to a first external pin of the IC either directly or via a buffer circuit located within the IC in response to a command from the external test station; and measuring the first internal signal by the external test station by monitoring the first external pin of the IC to produce a measured value; further including calibrating the buffer circuit by; providing a known calibration signal to a second external pin of the IC; coupling the known calibration signal to the first external pin of the IC via the buffer circuit in response to a command from the external test station; and measuring the known calibration signal after it is buffered by monitoring the first external pin of the IC by the external test station to produce a calibration value. - View Dependent Claims (2, 3, 4)
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5. A method for testing an integrated circuit, the method comprising:
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generating a plurality of internal signals within the integrated circuit (IC); selecting a first internal signal from the plurality of internal signals in response to a command from an external test station; coupling the first internal signal to a first external pin of the IC either directly or via a buffer circuit located within the IC in response to a command from the external test station; and measuring the first internal signal by the external test station by monitoring the first external pin of the IC to produce a measured value; further including; determining a common mode of the first internal signal; and selecting from among more than one buffer to couple the first internal signal to the first external test pin in accordance with the common mode of the first internal signal. - View Dependent Claims (6, 7)
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Specification