US3590284A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Filter circuit
Assignee: Hitachi Ltd
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Filing: 1968-03-08
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Granted: 1971-06-29
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Expires: 1988-03-08
Abstract
Abstract A filter circuit comprising a low (or high)-pass filter having a third order transfer function and a phase shifter having a first order transfer function. An output of the phase shelter is subtracted (added) by a subtractor (adder) from (to) an output of the low (high)-pass filter, whereby a desired third order transfer function equivalent to that of a high (low)-pass filter is obtained as a transfer function between an input of the filter circuit and an output of the subtractor (adder).
Inventors
- 👤 Masami Yamane
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 07:58
CPC Classifications
H; H03; H03H; H03H11/00; H03H11/02; H03H11/34
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
55 words
A filter circuit comprising: a low-pass filter having a third order transfer function a phase shifter having a first order transfer function means for applying an input signal to said low-pass filter and said phase shifter, and a subtractor circuit for subtracting an output of said phase shifter from an output of said low-pass filter.
Claim 2
Dependent Claim
55 words
A filter circuit comprising: a low-pass filter having a third order transfer function a phase shifter having a first order transfer function means for applying an input signal to said low-pass filter and said phase shifter, and a subtractor circuit for subtracting an output of said phase shifter from an output of said low-pass filter.
Claim 3
Dependent Claim
57 words
Filter circuit comprising: a high pass filter having a third order transfer function a phase shifter having a first order transfer function means for applying an input signal to said high pass filter and said phase shifter, and an adder circuit for adding an output of said high pass filter to an output of said phase shifter.
Claim 4
Dependent Claim
57 words
Filter circuit comprising: a high pass filter having a third order transfer function a phase shifter having a first order transfer function means for applying an input signal to said high pass filter and said phase shifter, and an adder circuit for adding an output of said high pass filter to an output of said phase shifter.
Claim 5
Dependent Claim
103 words
A filter circuit comprising: a phase shifter having a first order transfer function, a filter which substantially attenuates a portion of the frequency spectrum and is defined by a third order transfer function, means for applying an input signal to said filter and said phase-shifter and means for combining the outputs of said phase-shifter said filter, wherein said filter is a high pass filter whose transfer function is represented by and wherein said combining means is a means for adding the output of said phase-shifter to the output of said high pass filter, whereby the gain-frequency characteristic of said filter is substantially flattened.
Claim 6
Dependent Claim
103 words
A filter circuit comprising: a phase shifter having a first order transfer function, a filter which substantially attenuates a portion of the frequency spectrum and is defined by a third order transfer function, means for applying an input signal to said filter and said phase-shifter and means for combining the outputs of said phase-shifter said filter, wherein said filter is a high pass filter whose transfer function is represented by and wherein said combining means is a means for adding the output of said phase-shifter to the output of said high pass filter, whereby the gain-frequency characteristic of said filter is substantially flattened.
Claim 7
Dependent Claim
102 words
A filter circuit comprising: a phase shifter having a first order transfer function, a filter which substantially attenuates a portion of the frequency spectrum and is defined by a third order transfer function, means for applying an input signal to said filter and sAid phase-shifter and means for combining the outputs of said phase-shifter and said filter, wherein said filter is a low-pass filter whose transfer function is represented by and wherein said combining means is a means for subtracting the output of said phase-shifter from the output of said low-pass filter, whereby the gain-frequency characteristic of said filter is substantially flattened.
Claim 8
Dependent Claim
102 words
A filter circuit comprising: a phase shifter having a first order transfer function, a filter which substantially attenuates a portion of the frequency spectrum and is defined by a third order transfer function, means for applying an input signal to said filter and sAid phase-shifter and means for combining the outputs of said phase-shifter and said filter, wherein said filter is a low-pass filter whose transfer function is represented by and wherein said combining means is a means for subtracting the output of said phase-shifter from the output of said low-pass filter, whereby the gain-frequency characteristic of said filter is substantially flattened.
Claim 9
Dependent Claim
50 words
A filter circuit according to claim 3, wherein said phase-shifter comprises a resistance-capacitance network and wherein said adding means comprises a first emitter follower circuit, one of the inputs of which is connected to said resistance-capacitance network, whereby the first order of transfer function of said phase-shifter is defined by
Claim 10
Dependent Claim
73 words
A filter circuit according to claim 5, wherein said high pass filter comprises a plurality of resistance-capacitance networks, each connected in series with respect to the emitter follower circuits so as to define said third order transfer function and wherein said adding means comprises a second emitter follower circuit the input of which is connected to the output of said first emitter follower circuit and to the output of said high pass filter.
Claim 11
Dependent Claim
49 words
A filter circuit according to claim 4, wherein said phase-shifter comprises a resistance-capacitance network and wherein said subtracting means comprises a third emitter follower circuit one of the outputs of which is connected to said resistance-capacitance network, whereby said first order transfer function of said phase-shifter is defined by
Claim 12
Dependent Claim
71 words
A filter circuit according to claim 7, wherein said low-pass filter comprises a plurality of resistance-capacitor networks each connected in series with respect to the emitter follower circuits so as to define said third order transfer function and wherein said subtracting means comprises a fourth emitter follower circuit the input of which is connected to the output of said third emitter follower circuit and to the output of said low-pass filter.
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) | 1974-06-28 | 1974-12-28 | 1975-06-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-06-28 | 1978-12-28 | 1979-06-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-06-28 | 1982-12-28 | 1983-06-29 | $7700.00 | Window Closed / Lapsed |