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Patent US3881158A successfully refreshed from Google Patents.
US3881158A
Expired / Lapsed
US
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Multipurpose active filter network
Assignee: AG Communication Systems Corp
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Filing: 1974-05-29
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Granted: 1975-04-29
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Expires: 1994-05-29
Abstract
Abstract An active biquadratic filter circuit having a plurality of nodes connected by admittances and including a pair of operational amplifiers and a pair of capacitors connected in a configuration providing optional lowpass, highpass, and allpass filter with certain of said functions being simultaneously obtainable.
Inventors
- 👤 Henry J Orchard
- 👤 Charles E Schmidt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 10:06
CPC Classifications
H; H03; H03H; H03H11/00; H03H11/02; H03H11/34
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
202 words
An active filter configuration having six nodes comprising: a first admittance connected between a first and second of said nodes; a second admittance connected between said second and third of said nodes; a third admittance connected between said third and fourth of said nodes: a fourth admittance connected between said fourth and fifth of said nodes; a fifth admittance connected between said fifth and sixth of said nodes; a voltage input terminal adapted for connection to an input voltage source having a common reference; a sixth admittance connected between said input terminal and said second node; a seventh admittance connected between said input terminal and said sixth node; each of said admittances comprising an RC two terminal network; a first differential input amplifier having an output connected to said third node; a second differential input amplifier having an output connected to said fifth node; circuit means connecting the inputs of said amplifier to said second, fourth and sixth nodes; said configuration providing a filter output terminal at one of nodes three and five for a filter output voltage having a common reference; said first node being connected to said common reference; and at least two of said admittances each containing a capacitor.
Claim 2
Dependent Claim
202 words
An active filter configuration having six nodes comprising: a first admittance connected between a first and second of said nodes; a second admittance connected between said second and third of said nodes; a third admittance connected between said third and fourth of said nodes: a fourth admittance connected between said fourth and fifth of said nodes; a fifth admittance connected between said fifth and sixth of said nodes; a voltage input terminal adapted for connection to an input voltage source having a common reference; a sixth admittance connected between said input terminal and said second node; a seventh admittance connected between said input terminal and said sixth node; each of said admittances comprising an RC two terminal network; a first differential input amplifier having an output connected to said third node; a second differential input amplifier having an output connected to said fifth node; circuit means connecting the inputs of said amplifier to said second, fourth and sixth nodes; said configuration providing a filter output terminal at one of nodes three and five for a filter output voltage having a common reference; said first node being connected to said common reference; and at least two of said admittances each containing a capacitor.
Claim 3
Dependent Claim
24 words
The filter circuit of claim 1, and an eighth admittance connected between said first and sixth nodes and providing a general non-minimum-phase biquadratic filter.
Claim 4
Dependent Claim
43 words
The filter circuit of claim 1, said first, second, third, fourth and seventh admittances each comprising a conductance; said fifth and sixth admittances each comprising a capacitor; said third node providing a lowpass output port; said fifth node comprising a highpass output port.
Claim 5
Dependent Claim
22 words
The filter circuit of claim 3, and an admittance connected between said first and sixth nodes providing a general non-minimum-phase biquadratic filter.
Claim 6
Dependent Claim
43 words
The filter circuit of claim 3, the inverting and non-inverting inputs of said first amplifier being connected to said fourth and sixth nodes respectively; and the inverting and non-inverting inputs of said second amplifier being connected to said fourth and second nodes respectively.
Claim 7
Dependent Claim
43 words
The filter circuit of claim 2, the inverting and non-inverting inputs of said first amplifier being connected to said fourth and sixth nodes respectively; and the inverting and non-inverting inputs of said second amplifier being connected to said fourth and second nodes respectively.
Claim 8
Dependent Claim
43 words
The filter circuit of claim 4, the inverting and non-inverting inputs of said first amplifier being connected to said fourth and sixth nodes respectively; and the inverting and non-inverting inputs of said second amplifier being connected to said fourth and second nodes respectively.
Claim 9
Dependent Claim
19 words
The filter circuit of claim 5, said fifth and sixth admittances each comprising conductances in combination with said capacitors.
Claim 10
Dependent Claim
43 words
The filter circuit of claim 1, the inverting and non-inverting inputs of said first amplifier being connected to said second and sixth nodes respectively; and the inverting and non-inverting inputs of said second amplifier being connected to said fourth and sEcond nodes respectively.
Claim 11
Dependent Claim
23 words
The filter circuit of claim 9, and an eighth admittance connected between said first and sixth nodes providing a general non-minimum-phase biquadratic filter.
Claim 12
Dependent Claim
42 words
The filter of claim 3, the inverting and non-inverting inputs of said first amplifier being connected to said second and sixth nodes respectively; and the inverting and non-inverting inputs of said second amplifier being connected to said fourth and second nodes respectively.
Claim 13
Dependent Claim
45 words
A bandpass filter as defined in claim 9, said first and third admittances each comprising a capacitor, said second, fourth, fifth, sixth and eighth admittances each comprising a conductance, and said seventh admittance being of zero value; and said output terminal being at node (5).
Claim 14
Dependent Claim
43 words
The filter circuit of claim 1, the inverting and non-inverting inputs of said first amplifier being connected to said fourth and sixth nodes respectively; and the inverting and non-inverting inputs of said second amplifier being connected to said sixth and second nodes respectively.
Claim 15
Dependent Claim
24 words
The filter circuit of claim 13, and an eighth admittance connected between said first and sixth nodes and providing a general non-minimum-phase biquadratic filter.
Claim 16
Dependent Claim
43 words
The filter circuit of claim 3, the inverting and non-inverting inputs of said first amplifier being connected to said fourth and sixth nodes respectively; and the inverting and non-inverting inputs of said second amplifier being connected to said sixth and second nodes respectively.
Claim 17
Dependent Claim
43 words
The filter circuit of claim 1, the inverting and non-inverting inputs of said first amplifier being connected to said fourth and second nodes respectively; and the inverting and non-inverting inputs of said second amplifier being connected to said sixth and second nodes respectively.
Claim 18
Dependent Claim
24 words
The filter circuit of claim 16, and an eighth admittance connected between said first and sixth nodes and providing a general non-minimum-phase biquadratic filter.
Claim 19
Dependent Claim
43 words
The filter circuit of claim 3, the inverting and non-inverting inputs of said first amplifier being connected to said fourth and second nodes respectively; and the inverting and non-inverting inputs of said second amplifier being connected to said sixth and second nodes respectively.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-04-28 | 1978-10-28 | 1979-04-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-28 | 1982-10-28 | 1983-04-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-28 | 1986-10-28 | 1987-04-29 | $7700.00 | Window Closed / Lapsed |