US4078205A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electronic filter circuit
Assignee: Honeywell International Inc
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Filing: 1975-11-03
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Granted: 1978-03-07
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Expires: 1995-11-03
Abstract
Abstract To eliminate the high frequency portion of an input signal while permitting low frequency and DC portions to pass, the electronic filter utilizes an n-1 order active network in combination with a capacitor to generate a shunt current, thereby providing a low pass filter having n-order operating characteristics. Included in the active network is an active element, such as an operational amplifier, which responds to an input signal by creating a voltage across the capacitor, resulting in a shunt current that in turn provides the desired filter characteristics. In certain special cases the n-order active filter can utilize a differentiating element in combination with n-2 order active network along with the capacitor to achieve n-order operating characteristics.
Inventors
- 👤 Michael Marion Van Schoiack
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 04:30
CPC Classifications
H; H03; H03H; H03H11/00; H03H11/02; H03H11/04; H03H11/12; H03H11/126
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
59 words
An n-order active shunt filter comprising: terminal means for receiving an input signal from a signal source; an n-1 order active network connected across said terminals and responsive to said input signal; and capacitor means, operatively connected between said active network means and said terminal means, for generating a shunt current in cooperation with said n-1 order active network.
Claim 2
Dependent Claim
59 words
An n-order active shunt filter comprising: terminal means for receiving an input signal from a signal source; an n-1 order active network connected across said terminals and responsive to said input signal; and capacitor means, operatively connected between said active network means and said terminal means, for generating a shunt current in cooperation with said n-1 order active network.
Claim 3
Dependent Claim
134 words
An n-order active shunt filter comprising: a set of input terminals for receiving an input signal from a signal source that includes a load impedence Z L including a load resistance R L ; capacitor means, including a capacitor C, operatively connected to one of said terminals for transmitting a shunt current; and an n-1 order active network, operatively connected to said input terminals and said capacitor means, effective to shunt a current through said capacitor C from the output of the filter, wherein said active network has a transfer function: ##EQU28## wherein D = A n S n + A n-1 S n-1 + . . . + AS + 1, S represents the Laplace operator and A n + A n-1 + . . . + A represent the filter polynomial coefficients.
Claim 4
Dependent Claim
134 words
An n-order active shunt filter comprising: a set of input terminals for receiving an input signal from a signal source that includes a load impedence Z L including a load resistance R L ; capacitor means, including a capacitor C, operatively connected to one of said terminals for transmitting a shunt current; and an n-1 order active network, operatively connected to said input terminals and said capacitor means, effective to shunt a current through said capacitor C from the output of the filter, wherein said active network has a transfer function: ##EQU28## wherein D = A n S n + A n-1 S n-1 + . . . + AS + 1, S represents the Laplace operator and A n + A n-1 + . . . + A represent the filter polynomial coefficients.
Claim 5
Dependent Claim
19 words
The active shunt filter of claim 2 wherein said n-1 active network is capacitively coupled to said input terminals.
Claim 6
Dependent Claim
87 words
The active shunt filter of claim 2 wherein n = 1 and said n-1 active network includes: an operational amplifier operatively connected to one of said terminals effective to receive the input signal at its negative input terminal; a resistor interposed between said operational amplifier's negative input terminal and said input terminal; a resistive feedback network connecting the output of said operational amplifier with the negative input terminal of said operational amplifier; and means for operatively connecting the output of said operational amplifier to said capacitor C.
Claim 7
Dependent Claim
105 words
An n-order active shunt filter comprising: a set of input terminals for receiving an input signal from a signal source that includes a load resistance R L ; capacitor means including a capacitor C operatively connected to one of said terminals for transmitting a shunt current; and an n-1 order active network, operatively connected to said input terminals, effective to shunt a current through said capacitor C from the output of the filter, wherein said active network has a transfer function: ##EQU29## wherein S represents the Laplace operator and A n + A n-1 + . . . + A represents the filter polynomial coefficients.
Claim 8
Dependent Claim
105 words
An n-order active shunt filter comprising: a set of input terminals for receiving an input signal from a signal source that includes a load resistance R L ; capacitor means including a capacitor C operatively connected to one of said terminals for transmitting a shunt current; and an n-1 order active network, operatively connected to said input terminals, effective to shunt a current through said capacitor C from the output of the filter, wherein said active network has a transfer function: ##EQU29## wherein S represents the Laplace operator and A n + A n-1 + . . . + A represents the filter polynomial coefficients.
Claim 9
Dependent Claim
101 words
The active shunt filter of claim 5 wherein n=and said n-1 active network includes: an operational amplifier having its negative input terminal capacitively coupled to one of said input terminals; a resistor interposed between said operational amplifier's negative input terminal and said input terminal; means, including a resistor, for connecting said operational amplifier's positive terminal to the other of said input terminals; a feedback network, including a grounded capacitor operatively connected between two resistors, connecting the output of said operational amplifier with said negative input terminal; and means for operatively connecting the output of said operational amplifier to said capacitor C.
Claim 10
Dependent Claim
96 words
An n-order active low pass active shunt filter comprising: a set of input terminals for receiving an input signal from a signal source including a load resistance R L and a load capacitance C L connected in parallel; an n-1 order active network, operatively connected to said input terminals, effective to shunt a current through a capacitor C from the output of the filter, wherein said active network has a transfer function: ##EQU30## wherein S represents the Laplace operator and A n + A n-1 + . . . + A represents the filter polymonial coefficients.
Claim 11
Dependent Claim
96 words
An n-order active low pass active shunt filter comprising: a set of input terminals for receiving an input signal from a signal source including a load resistance R L and a load capacitance C L connected in parallel; an n-1 order active network, operatively connected to said input terminals, effective to shunt a current through a capacitor C from the output of the filter, wherein said active network has a transfer function: ##EQU30## wherein S represents the Laplace operator and A n + A n-1 + . . . + A represents the filter polymonial coefficients.
Claim 12
Dependent Claim
102 words
The active shunt filter of claim 7 wherein n = 2 and said n-1 active network includes: an operational amplifier having its negative input terminal coupled to one of said input terminals; a resistor interposed between said operational amplifier's negative input terminal and said input terminal; means, for connecting the positive terminal of said operational amplifier to the other of said input terminals; a feedback network, including a grounded capacitor operatively connected between two resistors, connecting the output of said operational amplifier with said negative input terminal; and means for operatively connecting the output of said operational amplifier to said capacitor C.
Claim 13
Dependent Claim
34 words
The n-order active filter of claim 7 wherein the values of A, R L , C, and C L are selected such that the transfer function of said n-1 order active network becomes: ##EQU31##
Claim 14
Dependent Claim
35 words
The n-order active filter of claim 9 wherein said n-1 order active network includes: a differentiating circuit operatively connected to one of said terminals; and an n-2 active network operatively connected to said differentiating circuit.
Claim 15
Dependent Claim
29 words
The n-order active filter of claim 10 wherein said differentiating circuit includes a capacitor C D operatively connected between one of said input terminals and said n-2 active network.
Claim 16
Dependent Claim
63 words
The n-order active filter of claim 11 wherein n = 2 and wherein said n-2 active network includes: an operational amplifier operatively connected to said capacitor C D ; a resistive feedback network connecting the output of said operational amplifier with an input terminal of said operational amplifier; and means for operatively connecting the output of said operational amplifier to said capacitor C.
Claim 17
Dependent Claim
65 words
The n-order filter of claim 11 wherein n= 3 and wherein said active network includes: an operational amplifier operatively connected to said capacitor C D ; means for connecting said capacitor C D to one of said input terminals; a feedback network, including a grounded capacitor operatively connected between two resistors; means for operatively connecting the output of said operational amplifier to said capacitor C.
Claim 18
Dependent Claim
50 words
The n-order active filter of claim 11 wherein said n-2 order active network includes an operational amplifier having substantially equal potential on each input terminal and combining capacitors C D and C into a single capacitor C A operatively connected between one of said input terminals and said operatively amplifier.
Claim 19
Dependent Claim
32 words
The n-order active filter of claim 14 additionally including: a feedback network, including a grounded capacitor operatively connected between two resistors, connecting the output of said operational amplifier to said capacitor C.
Claim 20
Dependent Claim
65 words
An n-order active low pass shunt filter comprising: a set of input terminals for receiving an input signal from a signal source; a differentiating circuit operatively connected to one of said input terminals; an n-2 order active network operatively connected between said differentiating circuit and said other input terminal; and a capacitor C, operatively connected between said n-2 active network and said first input terminal.
Claim 21
Dependent Claim
65 words
An n-order active low pass shunt filter comprising: a set of input terminals for receiving an input signal from a signal source; a differentiating circuit operatively connected to one of said input terminals; an n-2 order active network operatively connected between said differentiating circuit and said other input terminal; and a capacitor C, operatively connected between said n-2 active network and said first input terminal.
Claim 22
Dependent Claim
17 words
The active filter of claim 16 wherein said signal source includes a load resistor R L .
Claim 23
Dependent Claim
44 words
The n-order active filter of claim 17 wherein the combined transfer function of said differentiating and said n-2 network is: ##EQU32## wherein S represents the Laplace operator and A n + A n-1 + . . . + A represents the filter polynomial coefficients.
Claim 24
Dependent Claim
29 words
The n-order active filter of claim 18 wherein said differentiating circuit includes a capacitor C D operatively connected between one of said input terminals and said n-2 active network.
Claim 25
Dependent Claim
62 words
The n-order active filter of claim 19 wherein n = 2 and wherein said n-2active network includes: an operational amplifier operatively connected to said capacitor C D ; a resistive feedback network connecting the output of said operational amplifier with an input terminal of said operational amplifier; and means for operatively connecting the output of said operational amplifier to said capacitor C.
Claim 26
Dependent Claim
65 words
The n-order filter of claim 19 wherein n=3 and wherein said n-2 active network includes: an operational amplifier operatively connected to said capacitor C D ; means for connecting said capacitor C D to one of said input terminals; a feedback network, including a grounded capacitor operatively connected between two resistors; means for operatively connecting the output of said operational amplifier to said capacitor C.
Claim 27
Dependent Claim
50 words
The n-order active filter of claim 19 wherein said n-2 order active network includes an operational amplifier having substantially equal potential on each input terminal and combining capacitors C D and C into a single capacitor C A operatively connected between one of said input terminals and said operational amplifier.
Claim 28
Dependent Claim
48 words
The n-order active filter of claim 22 additionally including: a feedback network, including a grounded capacitor operatively connected between two resistors, connecting the output of said operational amplifier with its negative input terminal; and means for operatively connecting the output of said operational amplifier to said capacitor C.
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) | 1981-03-06 | 1981-09-05 | 1982-03-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-03-06 | 1985-09-05 | 1986-03-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-03-06 | 1989-09-05 | 1990-03-07 | $7700.00 | Window Closed / Lapsed |