US 6,822,435 B2Granted

Comparator circuit for differential swing comparison and common-mode voltage comparison

AssigneeNPTest, LLC

InventorToshihiro Nomura

Life of this patent

Estimating the term…

Loading patent…

Abstract

A comparator circuit includes at least one transconductance stage that receives two test voltages and two reference voltages. The transconductance stage produces two test currents that are proportional to the test voltages and two reference currents. A switching circuit is coupled to the transconductance stage. The switching circuit has two output terminals that are coupled to a conventional comparator stage. The switching circuit can combine the test currents with the reference currents to realize a differential swing comparison mode and a common-mode comparison mode as required for testing differential signals. Moreover, by disabling appropriate output signals from the at least one transconductance stage, a single-ended comparison mode is realized. By using two identical transconductance amplifiers, the non-linearity of the transconductance stage is advantageously canceled out.

Claims17

Dependent claims

An apparatus comprising:

at least one stage having a first input terminal that receives a first test voltage, a second input terminal that receives a first reference voltage, a third input terminal that receives a second test voltage, and a fourth input terminal that receives a second reference voltage, said at least one stage having a first output terminal upon which is produced a first test signal that is proportional to said first test voltage, a second output terminal upon which is produced a first reference signal that is proportional to said first reference voltage, a third output terminal upon which is produced a second test signal that is proportional to said second test voltage, and a fourth output terminal upon which is produced a second reference signal that is proportional to said second reference voltage;
a switching circuit coupled to said at least one stage, said switching circuit having a first output terminal that is switchably coupled to said first output terminal and one of said third output terminal and said fourth output terminal of said at least one stage, said switching circuit having a second output terminal that is switchably coupled to said first output terminal and one of said third output terminal and said fourth output terminal of said at least one stage;
and
a comparator circuit having a first input terminal coupled to said first output terminal of said switching circuit and a second input terminal coupled to said second output terminal of said switching circuit.

1 more element

Dependencies are inferred from the claim text.

Facts

Application: 10/057,134Filed 24 Jan 2002
Published: US 2003/0137289 A124 Jul 2003
Granted: 23 Nov 2004
Term ends: Not estimatedThe source records don’t support an estimate.

Classification4 codes

G01R 31/31703
Testing of digital circuits: comparison aspects, e.g. signature analysis, comparators
G01R 31/31924
Stimuli generation or application of test patterns to the device under test [DUT]: voltage or current aspects, e.g. driver, receiver
G01R 31/31932
With comparison between actual response and known fault free response: comparators
G01R
Measuring electric variables

Family

US 2003/0137289 A1Pre-grant publication · published 24 Jul 2003
US 6,822,435 B2This patent

From the US filing history. Foreign family members aren’t listed.

Timeline

Citations

Open elsewhere

Building an agent or pulling many patents? Use the API or MCP server instead of scraping pages. Get an API key