US4631495A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low-noise RF preamplifier (especially for nuclear magnetic resonance system)
Assignee: General Electric Co
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Filing: 1985-05-06
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Granted: 1986-12-23
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Expires: 2005-05-06
Abstract
Abstract A low-noise radio-frequency preamplifier, especially suited for use in the reception channel of a nuclear magnetic resonance spectrometer and the like, utilizes a low-noise input stage having a plurality of bipolar junction transistors effectively connected in radio-frequency parallel, but with each of the plurality of parallel bipolar transistors isolated from one another for direct current flow through at least one electrode thereof.
Inventors
- 👤 Otward M. Mueller
- 👤 William A. Edelstein
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 13:46
CPC Classifications
H; H03; H03F; H03F3/00; H03F3/189; H03F3/19; H03F1/00; H03F1/26
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
50 words
A radio-frequency (RF) preamplifier comprising: a linear low-noise input stage having a plurality N of bipolar junction transistors having like electrodes effectively connected in RF parallel, and with each of the base electrodes of said plurality of parallel bipolar junction transistors being isolated from one another for direct current flow.
Claim 2
Dependent Claim
50 words
A radio-frequency (RF) preamplifier comprising: a linear low-noise input stage having a plurality N of bipolar junction transistors having like electrodes effectively connected in RF parallel, and with each of the base electrodes of said plurality of parallel bipolar junction transistors being isolated from one another for direct current flow.
Claim 3
Dependent Claim
20 words
The preamplifier of claim 1, further comprising at least one additional gain stage serially connected after the low-noise input stage.
Claim 4
Dependent Claim
15 words
The preamplifier of claim 2, further comprising means for switch selecting the total preamplifier gain.
Claim 5
Dependent Claim
20 words
The preamplifier of claim 3, further comprising means for independently setting the collector current in each of the paralleled transistors.
Claim 6
Dependent Claim
20 words
The preamplifier of claim 2, further comprising means for independently setting the collector current in each of the paralleled transistors.
Claim 7
Dependent Claim
20 words
The preamplifier of claim 1, further comprising means for independently setting the collector current in each of the parallel transistors.
Claim 8
Dependent Claim
32 words
The preamplifier of claim 1, wherein the input stage transistors are each biased to have an optimum input impedance of about NxZ 0 , where Z 0 is a preselected characteristic impedance.
Claim 9
Dependent Claim
34 words
The preamplifier of claim 7, wherein N=2, Z 0 is about 50 ohms and the optimum source impedance of the preamplifier is between about 25 ohms and about 70 ohms at a predetermined frequency.
Claim 10
Dependent Claim
82 words
In combination in a nuclear magnetic resonance (NMR) sample investigation system: an antenna for receiving an NMR response signal; and a radio-frequency (RF) preamplifier comprising a linear low-noise input stage having a plurality N of bipolar junction transistors having like electrodes effectively connected in RF parallel and directly connected to said antenna without any additional impedance-matching network therebetween and with each of the base electrodes of said plurality of parallel bipolar junction transistors being isolated from one another for direct current flow.
Claim 11
Dependent Claim
82 words
In combination in a nuclear magnetic resonance (NMR) sample investigation system: an antenna for receiving an NMR response signal; and a radio-frequency (RF) preamplifier comprising a linear low-noise input stage having a plurality N of bipolar junction transistors having like electrodes effectively connected in RF parallel and directly connected to said antenna without any additional impedance-matching network therebetween and with each of the base electrodes of said plurality of parallel bipolar junction transistors being isolated from one another for direct current flow.
Claim 12
Dependent Claim
23 words
The combination of claim 9, wherein said preamplifier further comprises at least one additional gain stage serially connected after the low-noise input stage.
Claim 13
Dependent Claim
15 words
The combination of claim 10, further comprising means for switch selecting the total preamplifier gain.
Claim 14
Dependent Claim
20 words
The combination of claim 11, further comprising means for independently setting the collector current in each of the paralleled transistors.
Claim 15
Dependent Claim
20 words
The combination of claim 10, further comprising means for independently setting the collector current in each of the paralleled transistors.
Claim 16
Dependent Claim
20 words
The combination of claim 9, further comprising means for independently setting the collector current in each of the paralleled transistors.
Claim 17
Dependent Claim
32 words
The combination of claim 9, wherein the input stage transistors are each biased to have an optimum input impedance of about NxZ 0 , where Z 0 is a preselected characteristic impedance.
Claim 18
Dependent Claim
34 words
The combination of claim 15, wherein N=2, Z 0 is about 50 ohms and the optimum source impedance of the preamplifier is between about 25 ohms and about 70 ohms at a predetermined frequency.
References Cited (Backward Citations)
US4090150A
Cited
US4348643A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-12-22 | 1990-06-23 | 1990-12-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-12-22 | 1994-06-23 | 1994-12-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-12-22 | 1998-06-23 | 1998-12-23 | $7700.00 | Window Closed / Lapsed |