Bi-Directional Buffer For Interfacing Test System Channel

• US 20070290676A1
• Filed: 08/28/2007
• Published: 12/20/2007
• Est. Priority Date: 12/21/2004
• Status: Active Grant

• Current Assignee: FormFactor Incorporated
• Original Assignee: FormFactor Incorporated
• Inventors: Miller, Charles
• Granted Patent: US 7,977,958 B2
• Time in Patent Office: Days
• US Class Current: 324/149
• CPC Class Codes: G01R 31/2889 Interfaces, e.g. between probe and tester G01R31/31905 and G01R1/07364 take precedence
• CPC Class Codes: G01R 31/31713 Input or output interfaces for test, e.g. test pins, buffers for scan test G01R31/318572

Abstract

An emitter follower or source follower transistor is provided in the channel of a wafer test system between a DUT and a test system controller to enable a low power DUT to drive a test system channel. A bypass resistor is included between the base and emitter of the emitter follower transistor to enable bi-directional signals to be provided between the DUT channel and test system controller, as well as to enable parametric tests to be performed. The emitter follower transistor and bypass resistor can be provided on the probe card, with a pull down termination circuit included in the test system controller. The test system controller can provide compensation for the base to emitter voltage drop of the emitter follower transistor.

Claims

1-20. -20. (canceled)

21. :

A probe card apparatus comprising;

a plurality of electrical connections to communications channels to a tester for testing an electronic device;

a plurality of probes disposed to contact the electronic device; and

in a first communication channel, a first amplifier for amplifying a signal output by the electronic device and received at a first of the probes, the first amplifier providing the amplified signal to a first of the communications channels, and

a first by-pass electrical path for providing an electrical path to the first of the probes by-passing the first amplifier for test signals output by the tester and received at the first connection to the first of the communications channels.

22. :

The probe card apparatus of claim 21, wherein the first amplifier is a current amplifier for amplifying a current of the signal output by the electronic device.

23. :

The probe card apparatus of claim 22 further comprising a power supplied for supplying power to the first amplifier, the power having a voltage component sufficient for the amplifier to operate and the power having an additional voltage component sufficient to compensate for a voltage drop across the first amplifier.

24. :

The probe card apparatus of claim 22, further comprising;

a temperature sensor; and

a power supply circuit connected to the temperature sensor, the power supply circuit providing a voltage to the first amplifier that varies with a temperature sensed by the temperature sensor.

25. :

The probe card apparatus of claim 24 further comprising a memory connected to the power supply circuit for storing data correlating temperature versus voltage to the first amplifier.

26. :

The probe card apparatus of claim 21 further comprising;

a plurality of second amplifiers each for amplifying one of a plurality of second signals output by the electronic device and received at one of a second of the probes, each of the second amplifiers providing the one of the amplified second signals to one of a second plurality of connections to second ones of the communications channels; and

a plurality of second by-pass electrical paths each for providing an electrical path to one of the second of the probes by-passing one of the second amplifiers for test signals output by the tester and received at one of the second connections to one of the second of the communications channels.

27. :

The probe card apparatus of claim 21, wherein the first communication channel is bi-directional.

28. :

The probe card apparatus of claim 28 a, wherein the first communication channel is passively bi-directional.

29. :

A method of testing an electronic device, the method comprising;

providing a plurality of test signals from a tester for controlling testing of the electronic device through ones of communications channels between the tester and the electronic device, the providing comprising providing one of the test signals through a first by-pass path of a first of the communications channels to a first probe in contact with the electronic device; and

amplifying an output signal output by the electronic device and received at the first probe; and

providing the amplified output signal to the tester through the first communications channel,

wherein the first by-pass path by-passes the first amplifier.

30. :

The method of claim 29, wherein the amplifying comprises amplifying a current of the output signal.

31. :

The method of claim 30 further comprising providing power to the first amplifier, the power having a voltage component sufficient for the amplifier to operate and the power having an additional voltage component sufficient to compensate for a voltage drop across the first amplifier.

32. :

The method of claim 30, further comprising;

sensing a temperature adjacent the first amplifier; and

varying a voltage component of power supplied to the first amplifier in accordance with the sensed temperature.

33. :

The method of claim 29, wherein the providing a plurality of test signals further comprises providing ones of the test signals through second by-pass paths of second ones of the communications channels to second probes in contact with the electronic device; and

amplifying output signals output by the electronic device and received at the second probes; and

providing the amplified output signals to the tester through the second communications channels,

wherein the second by-pass paths by-pass the second amplifiers.

34. :

The method of claim 29 further comprising selectively connecting an output of the first amplifier through a resistor to ground.

35. :

The method of claim 29 further comprising selectively providing a current sink path from an output of the first amplifier.