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Patent US5293087A successfully refreshed from Google Patents.
US5293087A
Expired / Lapsed
US
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Filter circuit and filter integrated circuit
Assignee: Fujitsu Ltd
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Filing: 1992-10-19
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Granted: 1994-03-08
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Expires: 2012-10-19
Abstract
Abstract A filter circuit and a filter integrated circuit capable of being used in a high frequency band comprises a first resistor R 1 connected between an input signal source and an emitter of a common-base transistor TR 1 , a first capacitor C 1 connected between said input signal source and a reference voltage point, a second capacitor C 2 connected between said input signal source and a collector of the common-base transistor TR 1 , and a second resistor R 2 connected between the collector of the common-base transistor and the reference voltage point. Thus, a low-pass filter which operates in a high frequency band and suppresses the influence of characteristic parameters over the filter characteristic can be constructed.
Inventors
- 👤 Hiroshi Hamano
- 👤 Izumi Amemiya
- 👤 Yoichi Oikawa
- 👤 Takuji Yamamoto
- 👤 Takeshi Ihara
- 👤 Yoshinori Nishizawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 02:28
CPC Classifications
H; H03; H03H; H03H11/00; H03H11/02; H03H11/04; H03H11/12; H03H11/1213
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
71 words
A low-pass filter circuit, comprising: a common-base transistor; a first resistor connected between an input signal source and an emitter of a common-base transistor; the first capacitor connected between said input signal source and a reference voltage point; a second capacitor connected between said input signal source and a collector of the common-base transistor; and a second resistor connected between the collector of the common-base transistor and the reference voltage point.
Claim 2
Dependent Claim
71 words
A low-pass filter circuit, comprising: a common-base transistor; a first resistor connected between an input signal source and an emitter of a common-base transistor; the first capacitor connected between said input signal source and a reference voltage point; a second capacitor connected between said input signal source and a collector of the common-base transistor; and a second resistor connected between the collector of the common-base transistor and the reference voltage point.
Claim 3
Dependent Claim
52 words
The low-pass filter circuit as set forth in claim 1, wherein: the resistance value of said second resistor is set to be relatively small and thus the internal impedance of said common-base transistor connected in parallel with said second resistor is relatively large enough to be negligible in a high frequency band.
Claim 4
Dependent Claim
59 words
The low-pass filter circuit as set forth in claim 1, wherein: the resistance value of said second resistor is set to be relatively small and thus the composite impedance of said common-base transistor, connected in parallel with said second resistance, due to its base resistance and base-collector capacitance is large enough to be negligible in a high frequency band.
Claim 5
Dependent Claim
72 words
A low-pass filter integrated circuit, comprising: a common-base transistor; a first resistor connected between an input signal source and an emitter of said common-base transistor; a first capacitor connected between said input signal source and a reference voltage point; a second capacitor connected between said input signal source and a collector of the common-base transistor; and a second resistor connected between the collector of the common-base transistor and the reference voltage point.
Claim 6
Dependent Claim
72 words
A low-pass filter integrated circuit, comprising: a common-base transistor; a first resistor connected between an input signal source and an emitter of said common-base transistor; a first capacitor connected between said input signal source and a reference voltage point; a second capacitor connected between said input signal source and a collector of the common-base transistor; and a second resistor connected between the collector of the common-base transistor and the reference voltage point.
References Cited (Backward Citations)
US3890577A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-03-07 | 1997-09-06 | 1998-03-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-03-07 | 2001-09-06 | 2002-03-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-03-07 | 2005-09-06 | 2006-03-08 | $7700.00 | Window Closed / Lapsed |