Driver with transmission path loss compensation

• US 6,360,180 B1
• Filed: 05/10/1999
• Issued: 03/19/2002
• Est. Priority Date: 05/10/1999
• Status: Active Grant

• Current Assignee: Teradyne Incorporated
• Original Assignee: Teradyne Incorporated
• Inventors: Breger, Peter
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): PRETLOW, DEMETRIUS R
• Application Number:
  US09/309,134
• Time in Patent Office: 1,044 Days
• Field of Search: 702/108, 702/57-59, 702/67, 702/68, 702/117-123, 702/182-185, 327/317, 327/382, 327/285, 327/321, 327/165, 326/32, 326/26, 324/765, 716/4
• US Class Current: 702/108
• CPC Class Codes: G01R 31/31924 Voltage or current aspects, e.g. driver, receiver

Abstract

A driver for applying a deterministic waveform along a lossy transmission path to a device-under-test is disclosed. The driver includes a signal generator for producing a substantially square-wave signal at an output node and an injector coupled to the output node for modifying the square-wave signal to pre-compensate for expected losses along the lossy path.

Claims

1. A driver for applying a deterministic waveform along a lossy transmission path to a device-under-test, said driver including:

a signal generator for producing a substantially square-wave signal at an output node; and

an injector coupled to said output node for modifying said square-wave signal to pre-compensate for expected losses along said lossy path.

2. A driver according to claim 1 wherein said signal generator comprises:

a first clamping circuit for setting a first signal level;

a second clamping circuit for generating a second signal level; and

an output switch coupled to said first and second clamping circuits and operative to selectively pass said first and second signal levels to said output node.

3. A driver according to claim 1 wherein said injector comprises:

an output sampler coupled to said output node; and

an RC network coupled to said output sampler to generate a compensation signal based on the signal sampled by said output sampler.

4. A driver according to claim 3 wherein said compensation signal comprises injection current to modify a portion of said substantially square-wave signal.

5. A channel card for use in a semiconductor tester to drive and capture signals to and from a device-under-test, said channel card including:

a formatter;

a comparator having an input coupled to said device-under-test and an output feeding said formatter; and

a driver having an input coupled to said formatter and an output connected through a lossy transmission path to said device-under-test, said driver including;

a signal generator for producing a substantially square-wave signal at an output node; and

an injector coupled to said output node for modifying said square-wave signal to pre-compensate for expected losses along said lossy path.

6. A channel card according to claim 5 wherein said signal generator comprises:

a first clamping circuit for setting a first signal level;

a second clamping circuit for generating a second signal level; and

an output switch coupled to said first and second clamping circuits and operative to selectively pass said first and second signal levels to said output node.

7. A channel card according to claim 5 wherein said injector comprises:

an output sampler coupled to said output node; and

an RC network coupled to said output sampler to generate a compensation signal based on the signal sampled by said output sampler.

8. A method of applying a driving waveform from a driver output along a lossy signal path to a device-under-test, said method including the steps of:

establishing a first clamped signal level;

switching said driver output to said first clamped signal level; and

injecting energy into said output node to modify said first clamped signal level and compensate for losses to said clamped signal level along said lossy signal path.

9. A method according to claim 8 wherein said injecting step includes:

sampling the signal at said driver output; and

applying said energy at said output node at a level dependent on the signal sampled in said sampling step.