US4494212A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Variable gain amplifier
Assignee: PerkinElmer Instruments LLC
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Filing: 1984-07-06
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Granted: 1985-01-15
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Expires: 2004-07-06
Abstract
Abstract A variable gain amplifier with digital output is described. The amplifier is useful for but not limited to input range selection in chart recorders or other measuring instruments. To minimize the number of expensive presision resistors used in the gain selection network each selected range is approximated by switching. A software routine then adjusts the gain after digitizing to the correct value for the selected range. Both range switching and gain correction are controlled by a general purpose microprocessor which also is available for other duties in the instrument.
Inventors
- 👤 William C. Muellner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 20:36
CPC Classifications
H; H03; H03G; H03G3/00; H03G3/20; H03G3/30
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
119 words
A variable gain amplifier, having a plurality of selectable gain ranges, comprising, in combination: operational amplifier means, a multipath resistor feedback network connected to said operational amplifier means, semiconductor switch means for switching said multipath resistor feedback network into a selected one of the paths in said feedback network, an analog to digital converter connected to the output of said feedback network, microprocessor means for controlling said semiconductor switch means corresponding to the selected gain range, said microprocessor means storing in memory a correction factor for each of said gain ranges, and said microprocessor means applying the correction factor corresponding to the selected gain range to the output of said analog to digital converter to provide a corrected gain.
Claim 2
Dependent Claim
119 words
A variable gain amplifier, having a plurality of selectable gain ranges, comprising, in combination: operational amplifier means, a multipath resistor feedback network connected to said operational amplifier means, semiconductor switch means for switching said multipath resistor feedback network into a selected one of the paths in said feedback network, an analog to digital converter connected to the output of said feedback network, microprocessor means for controlling said semiconductor switch means corresponding to the selected gain range, said microprocessor means storing in memory a correction factor for each of said gain ranges, and said microprocessor means applying the correction factor corresponding to the selected gain range to the output of said analog to digital converter to provide a corrected gain.
Claim 3
Dependent Claim
36 words
The variable gain amplifier of claim 1, wherein said feedback network comprises a plurality of voltage semiconductor switch means, said divider paths including switches to select a plurality of voltage ratios determined by said divider paths.
Claim 4
Dependent Claim
16 words
The variable gain amplifier of claim 2 wherein said switch means comprise solid state digital switches.
Claim 5
Dependent Claim
22 words
The variable gain amplifier of claim 3 wherein said switch means are actuated by bits in PIA latches controlled by said microprocessor.
Claim 6
Dependent Claim
53 words
The variable gain amplifier of claim 1 wherein said correction factor is predetermined by said microprocessor means by applying a known input voltage to the amplifier and determining the value of said correction factor required to provide a correct output value from the analog to digital converter corresponding to the selected gain range.
Claim 7
Dependent Claim
53 words
The variable gain amplifier of claim 2 wherein said correction factor is predetermined by said microprocessor means by applying a known input voltage to the amplifier and determining the value of said correction factor required to provide a correct output value from the analog to digital converter corresponding to the selected gain range.
Claim 8
Dependent Claim
53 words
The variable gain amplifier of claim 3 wherein said correction factor is predetermined by said microprocessor means by applying a known input voltage to the amplifier and determining the value of said correction factor required to provide a correct output value from the analog to digital converter corresponding to the selected gain range.
Claim 9
Dependent Claim
53 words
The variable gain amplifier of claim 4 wherein said correction factor is predetermined by said microprocessor means by applying a known input voltage to the amplifier and determining the value of said correction factor required to provide a correct output value from the analog to digital converter corresponding to the selected gain range.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-01-15 | 1988-07-16 | 1989-01-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-01-15 | 1992-07-16 | 1993-01-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-01-15 | 1996-07-16 | 1997-01-15 | $7700.00 | Window Closed / Lapsed |