US5192884A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Active filter having reduced capacitor area but maintaining filter characteristics
Assignee: Toshiba Corp
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Filing: 1990-10-15
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Granted: 1993-03-09
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Expires: 2010-10-15
Abstract
Abstract An active filter comprises a differential-type voltage-controlled current source. A first resistor is connected between the first input terminal of the voltage-controlled current source and a first signal source. A second resistor is connected between the second input terminal of the voltage-controlled current source and the second signal source (or the output terminal of the voltage-controlled current source). The incremental transfer conductance gm of the filter becomes smaller by R 2 /(R 1 +R 2 ) compared to that of an active filter which does not contain the first and the second resistors of the active filter of the invention, where R 1 and R 2 are resistance values of the first and the second resistors, respectively.
Inventors
- 👤 Takahiro Kusano
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 12:32
CPC Classifications
H; H03; H03H; H03H11/00; H03H11/02; H03H11/04; H03H11/0422; H03H11/0433
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
105 words
An active filter in an integrated circuit comprising: a differential circuit voltage-controlled current source including a first and a second input terminal and an output terminal, said first input terminal being connected to a first signal source for supplying a signal to be filtered by the active filter; a first resistor connected between the output terminal and the second input terminal of the voltage controlled current source; a second resistor connected between the first input terminal and the second input terminal of the voltage-controlled current source; and a capacitor connected between a second signal source and the output terminal of the voltage controlled current source.
Claim 2
Dependent Claim
105 words
An active filter in an integrated circuit comprising: a differential circuit voltage-controlled current source including a first and a second input terminal and an output terminal, said first input terminal being connected to a first signal source for supplying a signal to be filtered by the active filter; a first resistor connected between the output terminal and the second input terminal of the voltage controlled current source; a second resistor connected between the first input terminal and the second input terminal of the voltage-controlled current source; and a capacitor connected between a second signal source and the output terminal of the voltage controlled current source.
Claim 3
Dependent Claim
22 words
An active filter in an integrated circuit as claimed in claim 1, wherein the second signal source has a voltage of ground.
Claim 4
Dependent Claim
34 words
An active filter in an integrated circuit as claimed in claim 1, wherein the first and the second input terminals of the voltage-controlled current source are a non-inverting input and an inverting input, respectively.
Claim 5
Dependent Claim
31 words
An active filter in an integrated circuit as claimed in claim 1, further comprising a buffer amplifier connected between the output terminal of the voltage-controlled current source and the first resistor.
Claim 6
Dependent Claim
175 words
An active filter comprising: a first differential circuit voltage-controlled current source including a first and a second input terminal and an output terminal; a first signal source connected to the first input terminal of the first voltage-controlled current source; a second differential circuit voltage-controlled current source including a first input terminal connected to the output terminal of the first voltage-controlled current source, a second input terminal, and an output terminal connected to the second input terminal of the second voltage controlled current source; a first resistor connected between the output terminal of the second voltage-controlled current source and the second input terminal of the first voltage-controlled current source; a second resistor connected between the first and the second input terminals of the first voltage-controlled current source; a second signal source; a first capacitor connected between the second signal source and the output terminal of the first voltage-controlled current source; and a second capacitor connected between the output terminal of the second voltage-controlled current source and the first input terminal of the first voltage-controlled current source.
Claim 7
Dependent Claim
175 words
An active filter comprising: a first differential circuit voltage-controlled current source including a first and a second input terminal and an output terminal; a first signal source connected to the first input terminal of the first voltage-controlled current source; a second differential circuit voltage-controlled current source including a first input terminal connected to the output terminal of the first voltage-controlled current source, a second input terminal, and an output terminal connected to the second input terminal of the second voltage controlled current source; a first resistor connected between the output terminal of the second voltage-controlled current source and the second input terminal of the first voltage-controlled current source; a second resistor connected between the first and the second input terminals of the first voltage-controlled current source; a second signal source; a first capacitor connected between the second signal source and the output terminal of the first voltage-controlled current source; and a second capacitor connected between the output terminal of the second voltage-controlled current source and the first input terminal of the first voltage-controlled current source.
Claim 8
Dependent Claim
198 words
An active filter comprising: a first differential circuit voltage-controlled current source including a first and a second input terminal and an output terminal; a first signal source connected to the first input terminal of the first voltage-controlled current source; a second differential circuit voltage-controlled current source including a first input terminal connected to the output terminal of the first voltage-controlled current source, a second input terminal, and an output terminal; a first resistor having a first terminal connected to the second input terminal of the first voltage-controlled current source; a second resistor connected to the first and the second input terminals of the first voltage-controlled current source; a second signal source; a first capacitor connected between the second signal source and the output terminal of the first voltage-controlled current source; a second capacitor connected between the output terminal of the second voltage-controlled current source and the first input terminal of the first voltage-controlled current source; and a buffer amplifier having an input connected to the output terminal of the second voltage-controlled current source and having an output connected to a second terminal of the first resistor and to the second input terminal of the second voltage-controlled current source.
Claim 9
Dependent Claim
198 words
An active filter comprising: a first differential circuit voltage-controlled current source including a first and a second input terminal and an output terminal; a first signal source connected to the first input terminal of the first voltage-controlled current source; a second differential circuit voltage-controlled current source including a first input terminal connected to the output terminal of the first voltage-controlled current source, a second input terminal, and an output terminal; a first resistor having a first terminal connected to the second input terminal of the first voltage-controlled current source; a second resistor connected to the first and the second input terminals of the first voltage-controlled current source; a second signal source; a first capacitor connected between the second signal source and the output terminal of the first voltage-controlled current source; a second capacitor connected between the output terminal of the second voltage-controlled current source and the first input terminal of the first voltage-controlled current source; and a buffer amplifier having an input connected to the output terminal of the second voltage-controlled current source and having an output connected to a second terminal of the first resistor and to the second input terminal of the second voltage-controlled current source.
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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) | 1996-03-08 | 1996-09-07 | 1997-03-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-03-08 | 2000-09-07 | 2001-03-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-03-08 | 2004-09-07 | 2005-03-09 | $7700.00 | Window Closed / Lapsed |