Apparatus and method for testing impedances of interconnect devices
First Claim
1. Apparatus for testing long term and intermittent impedance changes in an interconnect device used to couple data processing system components, said apparatus comprising:
- a bridge circuit means for receiving a radio frequency input signal, an interconnect device being coupled in one arm of said bridge circuit by means of a cable, said interconnect device having a coupled impedance coupled thereto, said coupled impedance and said interconnect device impedance being generally equal to a characteristic impedance of said cable coupling said interconnect device to said bridge circuit means, said bridge circuit means providing an output signal in response to said radio frequency input signal when a value of said interconnect device impedance in said bridge circuit means changes;
first signal processing means responsive to said output signal for providing a DC signal proportional to slow changes in said interconnect device impedance; and
second signal processing means responsive to said output signal for providing a count signal in response to intermittent changes in said interconnect device impedance.
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Accused Products
Abstract
In electronic devices, such as data processing systems that operate at high frequencies, the integrity of the interconnect or coupling apparatus transferring signals between component modules is critical to prevent compromise of information being transferred. However, the interconnect or coupling apparatus is subject to both long term and to short term impedance variations. Apparatus is disclosed for testing both the long term impedance changes and the rapid fluctuations that are not observable by current testing procedures. In addition, apparatus is disclosed for providing controllable rapid impedance changes to verify the operation of test apparatus, disclosed herein, for measuring the rapid impedance changes.
12 Citations
23 Claims
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1. Apparatus for testing long term and intermittent impedance changes in an interconnect device used to couple data processing system components, said apparatus comprising:
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a bridge circuit means for receiving a radio frequency input signal, an interconnect device being coupled in one arm of said bridge circuit by means of a cable, said interconnect device having a coupled impedance coupled thereto, said coupled impedance and said interconnect device impedance being generally equal to a characteristic impedance of said cable coupling said interconnect device to said bridge circuit means, said bridge circuit means providing an output signal in response to said radio frequency input signal when a value of said interconnect device impedance in said bridge circuit means changes; first signal processing means responsive to said output signal for providing a DC signal proportional to slow changes in said interconnect device impedance; and second signal processing means responsive to said output signal for providing a count signal in response to intermittent changes in said interconnect device impedance. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. The method of testing an impedance of an interconnect device used to couple data processing system components, said method comprising the steps of:
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coupling said interconnect device to a first end of a cable; coupling a coupled impedance to said interconnect device, said coupled impedance and an interconnect device having a characteristic impedance of said cable; coupling a second end of said cable in one arm of said bridge circuit, impedances of remaining arms of said bridge circuit being chosen to balance an impedance associated with said one arm; applying a radio frequency signal across said bridge circuit; detecting an imbalance signal when said bridge circuit is not balanced because of an intermittent change in impedance in said one arm when said change is greater than a preselected value; and processing said imbalance signal to provide a state signal during said intermittent change in impedance and to provide a clock signal with a frequency determined by said radio frequency signal. - View Dependent Claims (12, 13, 14, 15, 16)
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17. Test apparatus for testing intermittent and long term changes in an impedance of an interconnect device used in coupling data processing system components, said test apparatus comprising:
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bridge means with terminals for receiving a radio frequency signal, wherein said interconnect device is coupled to a first arm of said bridge means by means of a cable, wherein said interconnect device has a first impedance coupled thereto, said first impedance and an interconnect impedance providing a characteristic impedance for said cable, said bridge means for providing an imbalance signal when an impedance of said first arm changes from an initial value and said radio frequency signal is applied to said bridge means; amplifier means for receiving said imbalance signal and for providing a first output signal during a period when an intermittent first arm impedance change exceeds a preselected value, said amplifier means providing a clock signal having a frequency determined by said radio frequency signal during said period. - View Dependent Claims (18, 19, 20, 21, 22, 23)
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Specification