Patent US4178544A successfully refreshed from Google Patents.
US4178544A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrical measurement circuitry for low level AC signals
Assignee: Teradyne Inc
•
Filing: 1978-02-24
•
Granted: 1979-12-11
•
Expires: 1998-02-24
Abstract
Abstract Circuitry for making electrical measurements with low level ac signals, featuring a transformer with a coaxial cable primary having its outer shield grounded to provide an electrostatic shield, and a probe cable for a three-tipped probe in which four wires are arranged in two twisted pairs, one tip is connected to a wire in each pair, and the other two tips are respectively connected to the remaining two wires.
Inventors
- 👤 Mark S. Hoffman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 12:05
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/28; G01R31/316; G01R1/00; G01R1/02; G01R1/06; G01R1/067; G01R1/073
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
111 words
In electrical circuitry for measurement of low level ac signals during testing of an electrical element, comprising a three tip probe, and measurement circuitry connected to said probe to make successive voltage measurements between selected pairs of said tips while during each said measurement an ac test signal is injected into said element through the tip not in the then-selected pair, that improvement wherein the output cable from said probe to said measurement circuitry comprises four wires arranged in two twisted pairs, one said tip is connected to a said wire in each said twisted pair, and the other two said tips are respectively connected to the remaining two said wires.
Claim 2
Dependent Claim
111 words
In electrical circuitry for measurement of low level ac signals during testing of an electrical element, comprising a three tip probe, and measurement circuitry connected to said probe to make successive voltage measurements between selected pairs of said tips while during each said measurement an ac test signal is injected into said element through the tip not in the then-selected pair, that improvement wherein the output cable from said probe to said measurement circuitry comprises four wires arranged in two twisted pairs, one said tip is connected to a said wire in each said twisted pair, and the other two said tips are respectively connected to the remaining two said wires.
Claim 3
Dependent Claim
12 words
The improvement of claim 1 wherein said twisted pairs are individually shielded.
Claim 4
Dependent Claim
17 words
The circuitry of claim 1 wherein said one tip is in each said selected pair of tips.
Claim 5
Dependent Claim
20 words
The improvement of claim 1 wherein said source is a probe for testing IC elements mounted on a circuit board.
Claim 6
Dependent Claim
20 words
The improvement of either of claims 1 or 4 wherein said signals from said probe are in the microvolt range.
References Cited (Backward Citations)
US2685673A
Cited
US3048775A
Cited
US3300718A
Cited
US3283242A
Cited
GB1191637A
Cited
US3766470A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-12-10 | 1983-06-11 | 1983-12-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-12-10 | 1987-06-11 | 1987-12-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-12-10 | 1991-06-11 | 1991-12-11 | $7700.00 | Window Closed / Lapsed |