US4176312A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrical circuitry for measuring low level signals
Assignee: Teradyne Inc
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Filing: 1978-02-24
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Granted: 1979-11-27
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Expires: 1998-02-24
Abstract
Abstract Electrical circuitry for measuring low level signals comprising a source of ac signals to be measured, a synchronous detector clocked at the frequency of said ac, and a transformer coupling the source to the detector, improved in that, between the transformer and the detector, there are provided a wideband amplifier for amplifying both the information signal and noise present in the transformer output, followed by a filter having a passband of width intermediate those of the amplifier and the detector and centered on the clock frequency of the detector.
Inventors
- 👤 Joseph F. Wrinn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 06:14
CPC Classifications
G; G01; G01R; G01R19/00; G01R19/0046; G01R19/0053; G01R31/00; G01R31/28; G01R31/316
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
87 words
In electrical circuitry for measuring low level signals comprising a source of ac signals to be measured, a synchronous detector clocked at the frequency of said ac, and a transformer coupling said source to said detector, that improvement comprising, between said transformer and said detector, a wideband amplifier for amplifying both the information signal and noise present in the transformer output, followed by a filter having a passband of width intermediate those of said amplifier and said detector and centered on the clock frequency of the detector.
Claim 2
Dependent Claim
87 words
In electrical circuitry for measuring low level signals comprising a source of ac signals to be measured, a synchronous detector clocked at the frequency of said ac, and a transformer coupling said source to said detector, that improvement comprising, between said transformer and said detector, a wideband amplifier for amplifying both the information signal and noise present in the transformer output, followed by a filter having a passband of width intermediate those of said amplifier and said detector and centered on the clock frequency of the detector.
Claim 3
Dependent Claim
17 words
The improvement of claim 1 wherein said amplifier has a gain-bandwidth product of at least 5 MHz.
Claim 4
Dependent Claim
20 words
The improvement of claim 1 or 2 wherein said filter passband is no wider than 10% of said clock frequency.
Claim 5
Dependent Claim
19 words
The improvement of claims 1 or 2 wherein said detector has a bandwidth of no more than 15 Hz.
Claim 6
Dependent Claim
23 words
The improvement of claims 1 or 2 wherein said source is a probe for testing integrated circuit elements mounted on a circuit board.
Claim 7
Dependent Claim
16 words
The improvement of claim 5 wherein said signals from said probe are in the microvolt range.
References Cited (Backward Citations)
US3501694A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-11-26 | 1983-05-28 | 1983-11-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-11-26 | 1987-05-28 | 1987-11-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-11-26 | 1991-05-28 | 1991-11-27 | $7700.00 | Window Closed / Lapsed |