US3621407A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multiloop rc active filter apparatus having low-parameter sensitivity with low-amplifier gain
Assignee: National Aeronautics and Space Administration
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Filing: 1970-02-27
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Granted: 1971-11-16
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Expires: 1990-02-27
Abstract
Abstract A multiloop RC active filter network having low parameter sensitivity with low amplifier gain comprising at least two passive components and two voltage amplifiers one of which has a positive gain K1 which is less than unity and the other providing a negative gain of magnitude of K2 in the outer feedback loop. These circuits can provide any Q and can be made to oscillate with K1 and K2 within certain given ranges. Monolithic integrated circuit thick or thin film techniques are used in the preferred embodiment to provide the passive RC components.
Inventors
- 👤 William J Kerwin
- 👤 Charles V Shaffer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 05:16
CPC Classifications
H; H03; H03B; H03B5/00; H03B5/20; H03H; H03H11/00; H03H11/02; H03H11/04; H03H11/12; H03H11/1204
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
135 words
An active filter network comprising: electrode means for entering an input signal; electrode means for extracting an output signal; a first amplifier having first and second inputs and an output; a passive RC network having first, second, and third terminals; a second amplifier having at least one input and an output; said entering means being coupled to said extracting means; said entering means being further coupled to said second input of said first amplifier; said output of said first amplifier being coupled to said extracting means and said second terminal of said passive network; means interconnecting said first terminal of said passive network, said input of said second amplifier, and said first input of said first amplifier; and means for connecting said output of said second amplifier to said third terminal of said passive network.
Claim 2
Dependent Claim
135 words
An active filter network comprising: electrode means for entering an input signal; electrode means for extracting an output signal; a first amplifier having first and second inputs and an output; a passive RC network having first, second, and third terminals; a second amplifier having at least one input and an output; said entering means being coupled to said extracting means; said entering means being further coupled to said second input of said first amplifier; said output of said first amplifier being coupled to said extracting means and said second terminal of said passive network; means interconnecting said first terminal of said passive network, said input of said second amplifier, and said first input of said first amplifier; and means for connecting said output of said second amplifier to said third terminal of said passive network.
Claim 3
Dependent Claim
32 words
An active filter network as recited in claim 1 wherein said first input of said first amplifier is an inveRting input and said input of said second amplifier is a noninverting input.
Claim 4
Dependent Claim
19 words
An active filter network as claimed in claim 2 wherein said three-terminal passive RC network comprises a twin-T network.
Claim 5
Dependent Claim
41 words
An active filter network as claimed in claim 2 wherein said three-terminal passive RC network includes a distributed RC network, and a resistive element of said distributed RC network is connected between said first and second terminals of said passive network.
Claim 6
Dependent Claim
22 words
An active filter network as claimed in claim 2 wherein said passive RC network is comprised of lumped resistance and capacitive elements.
Claim 7
Dependent Claim
53 words
An active filter network as set forth in claim 2 wherein said passive RC network comprises a four-terminal distributed RC network having a resistive element and two capacitive elements, said second input of said first amplifier is unused, and the fourth terminal of said distributed RC network is connected to said entering means.
Claim 8
Dependent Claim
61 words
An active filter network as recited in claim 2 wherein said second amplifier has a second input connected to said entering means and the overall transfer function of said active filter network is where T1 1(p) is the transfer function of the passive network, K1 is the gain of said second amplifier and K2 is the gain of said first amplifier.
Claim 9
Dependent Claim
19 words
An active filter network as recited in claim 7 wherein the inputs of both of said amplifiers are differential.
Claim 10
Dependent Claim
19 words
An active filter network as recited in claim 2 wherein said inputs of said first amplifier are differential inputs.
Claim 11
Dependent Claim
32 words
An active filter network as recited in claim 9 wherein the gain of said first amplifier is in excess of one and the gain of said second amplifier is less than unity.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-11-15 | 1975-05-17 | 1975-11-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-15 | 1979-05-17 | 1979-11-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-15 | 1983-05-17 | 1983-11-16 | $7700.00 | Window Closed / Lapsed |