APPARATUS AND METHOD FOR PERFORMING A FOUR-POINT VOLTAGE MEASUREMENT FOR AN INTEGRATED CIRCUIT

• US 20070075712A1
• Filed: 09/30/2005
• Published: 04/05/2007
• Est. Priority Date: 09/30/2005
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Agere Systems Incorporated (Broadcom, Inc.)
• Inventors: Fitzgerald, David, Connolly, Barrett, Micko, Gregory, Petrie, Neil
• Granted Patent: US 7,218,125 B2
• Time in Patent Office: Days
• US Class Current: 324/715
• CPC Class Codes: G01R 31/2884 using dedicated test connectors, test elements or test circuits on the IC under test G01R31/2855 takes precedence
• CPC Class Codes: G01R 31/2886 Features relating to contacting the IC under test, e.g. probe heads; chucks G01R31/2865 takes precedence, test connections, e.g. test sockets, or probes per se, G01R1/04 or G01R1/06

Abstract

A method and apparatus for determining a voltage, such as a bias voltage, supplied by an integrated circuit. A nominal terminating resistor is connected across a first and a second input/output pads from which the voltage is supplied. The voltage is measured across third and fourth pads connected, respectively, to the first and second pads. In an alternative embodiment the functionality of the third and the fourth pads is multiplexed between chip operational circuitry unrelated to the voltage to be measured and a connection to the first and second pads for measuring the voltage.

Claims

1. A test apparatus for measuring a signal generated on an integrated circuit by a source during a testing mode, wherein the signal is supplied to first and second bond pads of the integrated circuit, and wherein during an operational mode an operational component is connected to the first and second bond pads, the test apparatus comprising:

first and second conductive elements for connecting the first and the second bond pads to a resistive element having a value related to a value of the operational component;

a measuring device; and

third and fourth conductive elements for connecting the measuring device to third and fourth bond pads of the integrated circuit responsive to the source.

2. The apparatus of claim 1 wherein the resistive element comprises a nominal resistance of a disk drive storage system read head.

3. The apparatus of claim 1 wherein the signal comprises a bias voltage for biasing a read head of a disk drive storage system.

4. The apparatus of claim 1 wherein the signal comprises a bias current for biasing the read head of a disk drive storage system.

5. The apparatus of claim 1 wherein the first, the second, the third and the fourth conductive elements comprise a first, a second, a third and a fourth test probe.

6. The apparatus of claim 1 wherein internal resistance of the measuring device is so large relative to a contact resistance associated with operation of the test apparatus that a measured signal measured by the test apparatus is insensitive to contact resistance.

7. The apparatus of claim 6 wherein influence of contact resistance on signal measurement introduces less than 1 percent error.

8. The apparatus of claim 1 wherein the integrated circuit further comprises a first and a second circuit element each configurable to an operable or a non-operable state and connected to the third and the fourth bond pads, respectively, and a first switchable element disposed between a first terminal of the source and the third bond pad, and a second switchable element disposed between a second terminal of the source and the fourth bond pad, wherein in the operational mode the first and the second circuit elements are configured to the operable state and the first and the second switchable elements are switched to an open state, and wherein in the testing mode the first and the second circuit elements are configured to the non-operable state and the first and the second switchable elements are switched to a closed state to connect the source across the third and the fourth bond pads.

9. The apparatus of claim 8 wherein the first and the second circuit elements comprise a first and a second output driver.

10. The apparatus of claim 8 wherein the first and the second switchable elements each comprises a metal oxide semiconductor field effect transistor each having a gate, each gate for receiving a control signal to switch the first and the second transistors to the opened state or to the closed state.

11. The apparatus of claim 1 wherein the measuring device comprises a first measuring device for measuring a first signal between the third bond pad and ground and a second measuring device for measuring a second signal between the fourth bond pad and ground, wherein the signal generated on the integrated circuit comprises a sum of the first and the second signals.

12. The apparatus of claim 1 wherein the measuring device comprises a measuring device for measuring the signal between the third and the fourth bond pads, and wherein the signal represents the signal generated on the integrated circuit.

13. A test apparatus for measuring a signal generated on an integrated circuit by a source during a testing mode, wherein the signal is supplied to first and second bond pads of the integrated circuit, and wherein during an operational mode an operational component is connected to the first and second bond pads, the test apparatus comprising:

first and second conductive elements for connecting the first and the second bond pads to a resistive element having a value related to a value of the operational component;

a measuring device; and

a third conductive element for connecting the measuring device to a first terminal of the source to measure a first signal and then connecting the measuring device to a second terminal of the source to measure a second signal, wherein the signal generated on the integrated circuit comprises a sum of the first and the second signals.

14. The apparatus of claim 13 wherein the resistive element comprises a nominal resistance of a disk drive storage system read head.

15. The apparatus of claim 13 wherein the signal comprises either a bias voltage for biasing a read head of a disk drive storage system or a bias current for biasing the read head of the disk drive storage system.

16. The apparatus of claim 13 wherein the first, the second and the third conductive elements comprise a first, a second and a third test probe.

17. The apparatus of claim 16 wherein an internal resistance of the measuring device is so large relative to a contact resistance of the third test probe that a measured signal measured by the test apparatus is insensitive to the contact resistance.

18. The apparatus of claim 13 wherein the integrated circuit further comprises a circuit element configurable to an operable or a non-operable state and connected to the third bond pad, and a first switchable transmission gate disposed between a first terminal of the source and the third bond pad, and a second switchable transmission gate disposed between a second terminal of the source and the third bond pad, wherein in the operational mode the circuit element is configured to the operable state and the first and the second transmission gates are switched to an opened state, and wherein in the testing mode the circuit element is configured to the non-operable state and alternately the first transmission gate is switched to the opened state while the second transmission gate is switched to the closed state for measuring a first voltage or a first current, and the first transmission gate is switched to the closed state while the second transmission gate is switched to the opened state for measuring a second voltage or a second current, and wherein the voltage or the current generated on the integrated circuit comprises a sum of the first and the second voltages or a sum of the first and the second currents.

19. The apparatus of claim 18 wherein the circuit element comprises an output driver.

20. The apparatus of claim 18 wherein the first and the second switchable transmission gates each comprises a metal oxide semiconductor field effect transistor each having a gate, each gate for receiving a control signal to switch the first and the second switchable transmission gates to the open state or to the closed state.

21. An apparatus for measuring a voltage or a current generated on an integrated circuit and supplied to first and second integrated circuit bond pads, wherein the integrated circuit comprises first and second contact regions each switchably connected to the first and the second bond pads through a respective switching element, the apparatus comprising:

a resistance for connecting across the first and the second bond pads, wherein the resistance represents the resistance of an element connected across the first and the second bond pads for receiving the voltage or current during operation of the integrated circuit;

a controller for controlling the first and the second switching elements to a closed configuration; and

a measuring device connected across the first and second terminals for measuring the voltage or current supplied across the first and the second bond pads.

22. The apparatus of claim 21 wherein the measuring device further comprises a first and a second test probe each including a first terminal end connected to the measuring device and a second terminal end connected to one of the first and the second terminals, wherein the first and the second test probes exhibit a contact resistance.

23. The apparatus of claim 22 wherein internal resistance of the measuring device is at least 100 times larger than the contact resistance of the first and the second test probes.

24. A preamplifier for a disk drive data storage system, the preamplifier comprising:

a signal source;

first and second bond pads connected across the signal source;

first and second switching elements; and

third and fourth bond pads switchably connected to the signal source through the respective first and second switching elements, wherein in an operational mode the first and second switching elements are placed in an opened configuration, and wherein in a testing mode the first and the second switching elements are placed in a closed configuration.

25. The preamplifier of claim 24 wherein the signal source comprises a bias voltage source for biasing a read head of a disk drive storage system.

26. The preamplifier of claim 24 further comprising a first and a second circuit element each configurable to an operable or a non-operable state and connected to the third and the fourth bond pads, respectively, the first switching element disposed between a first terminal of the source and the third bond pad, and the second switching element disposed between a second terminal of the source and the fourth bond pad, wherein in the operational mode the first and the second circuit elements are configured to the operable state and the first and the second switching elements are placed in the opened configuration, and wherein in the testing mode the first and the second circuit elements are configured to the non-operable state and the first and the second switching elements are placed in the closed configuration to connect the source across the third and the fourth bond pads.

27. A method for measuring a signal generated by a source disposed on an integrated circuit during a test, wherein the signal is supplied to first and second bond pads of the integrated circuit, and wherein during an operating mode an operational component is connected across the first and second bond pads, the method comprising:

connecting a resistive element having a value related to a value of the operational component across the first and the second bond pads; and

connecting a measuring device to third and fourth bond pads of the integrated circuit responsive to the source to determine a measured signal.

28. The method of claim 27 wherein the third and the fourth bond pads are responsive to the source through respective first and second switching elements, the method further comprising:

switching the first and the second switching elements to a closed configuration to connect the source to the third and the fourth bond pads.

29. The method of claim 27 wherein the step of connecting the measuring device further comprises:

connecting the measuring device to the third integrated circuit bond pad to determine a first referenced signal with respect to a reference;

connecting the measuring device to the fourth integrated circuit bond pad to determine a second referenced signal with respect to the reference; and

combining the first and the second referenced signals to determine the measured signal.

30. The method of claim 27 wherein the step of connecting the measuring device comprises connecting the measuring device across the third and fourth integrated circuit bond pads to determine the measured signal.

31. The method of claim 27 wherein the resistive element comprises a resistive element having a resistance of a disk drive storage system read head.

32. The method of claim 27 wherein the step of connecting the measuring device further comprises connecting a first terminal of the measuring device to the third bond pad through a first test probe and connecting a second terminal of the measuring device to the fourth bond pad through a second test probe, wherein a resistance of the measuring device is greater than a contact resistance of both the first and the second test probes.

33. The method of claim 27 further comprising:

determining a signal across the resistive element; and

determining a contact resistance of the first and the second test probes from the signal across the resistive element and the measured signal.