Patent US5266852A successfully refreshed from Google Patents.
US5266852A
Expired / Lapsed
US
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Filter circuit for integrated circuit
Assignee: Sharp Corp
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Filing: 1992-02-19
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Granted: 1993-11-30
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Expires: 2012-02-19
Abstract
Abstract Transistors Q11 and Q12 constitute a first differential amplifier, their emitters are connected with each other by a resistor R1 and also connected respectively to constant-current sources CS11 and CS12. Transistors Q15 to Q17 constitute a second differential amplifier, and the collector of the transistor Q16 is connected with a current mirror 17. This current mirror circuit 17 is constituted by transistors Q18 and Q19 and resistors R3 and R4. The capacitor 22 is supplied with a current from the current mirror circuit 17, and its voltage is fed back through a buffer circuit 14 to the base of the transistor Q12 as a component of the first differential amplifier.
Inventors
- 👤 Toshihiko Shigenari
- 👤 Toshihide Miyake
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 09:30
CPC Classifications
H; H03; H03F; H03F3/00; H03F3/45; H03F3/45071; H03F3/45479; H03H; H03H11/00; H03H11/02; H03H11/04; H03H11/12; H03H11/1213
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
261 words
A filter circuit for an integrated circuit comprising: a first differential amplifier including first and second transistors having emitters connected with each other by a resistor and also connected respectively to first and second constant-current sources and having collectors connected to a power supply line through transistors wired to operate as diodes; a second differential amplifier including a third transistor having an emitter connected to a third constant-current source, a collector connected to the power supply line through a transistor used as a diode and a resistor and a base connected to the collector of said first transistor, and a fourth transistor having an emitter connected to said third constant-current source and a base connected to the collector of said second transistor; a voltage-input current-output type amplifier comprising a current mirror circuit including a fifth transistor having a collector and a base connected to the collector of said fourth transistor and an emitter connected through a resistor to the power supply line and a sixth transistor having a collector connected to a fourth constant-current source, a base connected to the base of said fifth transistor and an emitter connected through a resistor to the power supply line, said voltage-input current-output type amplifier using the base of said first transistor as an input terminal, and the base of said second transistor as a feedback input terminal, and the collector of said sixth transistor as an output terminal; and a buffer circuit having an input terminal thereof connected to said output terminal and an output terminal thereof connected to said feedback input terminal.
Claim 2
Dependent Claim
261 words
A filter circuit for an integrated circuit comprising: a first differential amplifier including first and second transistors having emitters connected with each other by a resistor and also connected respectively to first and second constant-current sources and having collectors connected to a power supply line through transistors wired to operate as diodes; a second differential amplifier including a third transistor having an emitter connected to a third constant-current source, a collector connected to the power supply line through a transistor used as a diode and a resistor and a base connected to the collector of said first transistor, and a fourth transistor having an emitter connected to said third constant-current source and a base connected to the collector of said second transistor; a voltage-input current-output type amplifier comprising a current mirror circuit including a fifth transistor having a collector and a base connected to the collector of said fourth transistor and an emitter connected through a resistor to the power supply line and a sixth transistor having a collector connected to a fourth constant-current source, a base connected to the base of said fifth transistor and an emitter connected through a resistor to the power supply line, said voltage-input current-output type amplifier using the base of said first transistor as an input terminal, and the base of said second transistor as a feedback input terminal, and the collector of said sixth transistor as an output terminal; and a buffer circuit having an input terminal thereof connected to said output terminal and an output terminal thereof connected to said feedback input terminal.
Claim 3
Dependent Claim
30 words
A filter circuit as claimed in claim 1, wherein said circuit further comprises a capacitor connected between said output terminal of said voltage-input current-output type amplifier and the ground line.
Claim 4
Dependent Claim
44 words
A filter circuit as claimed in claim 1, wherein said circuit further comprises a circuit to correct the base current of said sixth transistor so that the current value of said fourth constant-current source agrees with the collector current value of said sixth transistor.
Claim 5
Dependent Claim
26 words
A filter circuit as claimed in claim 3, wherein said third constant-current source and said fourth constant-current source are each formed by a current mirror circuit.
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) | 1996-11-29 | 1997-05-31 | 1997-11-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-11-29 | 2001-05-31 | 2001-11-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-11-29 | 2005-05-31 | 2005-11-30 | $7700.00 | Window Closed / Lapsed |