US3586990A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low-pass active parallel-t filter with zero source impedance
Assignee: GTE Automatic Electric Laboratories Inc
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Filing: 1969-10-30
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Granted: 1971-06-22
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Expires: 1989-10-30
Abstract
Abstract The input of the capacitive series arm contains two capacitors to function as the first series capacitor and also as an input voltage divider, the divider being connected between a source of input signal and the capacitive series arm to provide low-pass characteristics. Compared with low-pass filters using resistive voltage dividers, the resistance between the series capacitors and the source of input signal is low, and therefore the series capacitive arm has true reactance.
Inventors
- 👤 Gideon Willoner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 10:56
CPC Classifications
H; H03; H03H; H03H11/00; H03H11/02; H03H11/04; H03H11/12; H03H11/1295
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
207 words
An active parallel-T filter of the type having a resistive series arm and capacitive series arm, each of said arms having a usual respective shunt element, a buffer amplifier connected between the outputs of said arms and at least one of said shunt elements, said filter having a single input to be connected to a source of signal voltage, said filter being modified to obtain low-pass characteristiCs in that it has voltage dividing means to apply to said capacitive series arm a desired fraction of said signal voltage applied to the input of said resistive series arm, the improvement comprising first and second input capacitors substituted for a first series capacitor of said capacitive series arm, said capacitive series arm having a second series capacitor of the usual value C, said first input capacitor being connected between said input of said resistive series arm and the junction connecting said second series capacitor and a respective one of said shunt elements, said second input capacitor being connected between a common circuit terminal and the junction connecting said first input capacitor, said second series capacitor and said respective shunt element, and said input capacitors functioning as said voltage dividing means in addition to functioning as a first series capacitor.
Claim 2
Dependent Claim
207 words
An active parallel-T filter of the type having a resistive series arm and capacitive series arm, each of said arms having a usual respective shunt element, a buffer amplifier connected between the outputs of said arms and at least one of said shunt elements, said filter having a single input to be connected to a source of signal voltage, said filter being modified to obtain low-pass characteristiCs in that it has voltage dividing means to apply to said capacitive series arm a desired fraction of said signal voltage applied to the input of said resistive series arm, the improvement comprising first and second input capacitors substituted for a first series capacitor of said capacitive series arm, said capacitive series arm having a second series capacitor of the usual value C, said first input capacitor being connected between said input of said resistive series arm and the junction connecting said second series capacitor and a respective one of said shunt elements, said second input capacitor being connected between a common circuit terminal and the junction connecting said first input capacitor, said second series capacitor and said respective shunt element, and said input capacitors functioning as said voltage dividing means in addition to functioning as a first series capacitor.
Claim 3
Dependent Claim
55 words
In a filter as claimed in claim 1 wherein said first input capacitor has a value KC and said second input capacitor has a value (1-K)C where K is the ratio of the voltage applied to the input of said capacitive series arm to the voltage applied to the input of said resistive series arm.
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) | 1974-06-21 | 1974-12-21 | 1975-06-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-06-21 | 1978-12-21 | 1979-06-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-06-21 | 1982-12-21 | 1983-06-22 | $7700.00 | Window Closed / Lapsed |