US3715679A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Active rc delay equalizer
Assignee: AT&T Inc
•
Filing: 1971-07-29
•
Granted: 1973-02-06
•
Expires: 1991-07-29
Abstract
Abstract An active resistance-capacitance (RC) delay equalizer circuit which exhibits an ''''all-pass'''' transfer characteristic is disclosed. The quality factor, Q, and the center frequency of the equalizer delay characteristic are independently adjustably by sliding switches which alter predetermined circuit resistor values. The equalizer circuit is preferably realized using operational amplifiers bonded to a thin film circuit substrate.
Inventors
- 👤 P Fleischer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 02:22
CPC Classifications
H; H03; H03H; H03H11/00; H03H11/02; H03H11/26; H03H11/265; H04; H04B; H04B3/00; H04B3/02; H04B3/04; H04B3/14; H04B3/141
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
126 words
Active RC adjustable delay equalizer apparatus having an input terminal and an output terminal comprising: a first feedback amplifier having an input and output; a second feedback amplifier having an input and output; a first adjustable resistive T-network connecting said first amplifier output and the input of said second amplifier; a third feedback amplifier having an input and output, said output connected to said equalizer output terminal and resistively connected to the input of said first amplifier, and said input resistively connected to the output of said second amplifier; a second adjustable resistive T-network connecting the input and output of said second amplifier to said equalizer input terminal; and resistive circuit means coupling said equalizer input terminal to the inputs of said first and third amplifiers.
Claim 2
Dependent Claim
126 words
Active RC adjustable delay equalizer apparatus having an input terminal and an output terminal comprising: a first feedback amplifier having an input and output; a second feedback amplifier having an input and output; a first adjustable resistive T-network connecting said first amplifier output and the input of said second amplifier; a third feedback amplifier having an input and output, said output connected to said equalizer output terminal and resistively connected to the input of said first amplifier, and said input resistively connected to the output of said second amplifier; a second adjustable resistive T-network connecting the input and output of said second amplifier to said equalizer input terminal; and resistive circuit means coupling said equalizer input terminal to the inputs of said first and third amplifiers.
Claim 3
Dependent Claim
126 words
Active RC adjustable delay equalizer apparatus having an input terminal and an output terminal comprising: a first feedback amplifier having an input and output; a second feedback amplifier having an input and output; a first adjustable resistive T-network connecting said first amplifier output and the input of said second amplifier; a third feedback amplifier having an input and output, said output connected to said equalizer output terminal and resistively connected to the input of said first amplifier, and said input resistively connected to the output of said second amplifier; a second adjustable resistive T-network connecting the input and output of said second amplifier to said equalizer input terminal; and resistive circuit means coupling said equalizer input terminal to the inputs of said first and third amplifiers.
Claim 4
Dependent Claim
126 words
Active RC adjustable delay equalizer apparatus having an input terminal and an output terminal comprising: a first feedback amplifier having an input and output; a second feedback amplifier having an input and output; a first adjustable resistive T-network connecting said first amplifier output and the input of said second amplifier; a third feedback amplifier having an input and output, said output connected to said equalizer output terminal and resistively connected to the input of said first amplifier, and said input resistively connected to the output of said second amplifier; a second adjustable resistive T-network connecting the input and output of said second amplifier to said equalizer input terminal; and resistive circuit means coupling said equalizer input terminal to the inputs of said first and third amplifiers.
Claim 5
Dependent Claim
35 words
The equalizer as defined in claim 1 wherein at least one of said resistive T-networks further comprises: a first fixed resistive leg; a second slideably adjustable resistive leg; and a third slideably adjustable resistive leg.
Claim 6
Dependent Claim
23 words
The equalizer as defined in claim 1 wherein at least one of said adjustable resistive T-networks exhibits a geometric variation in effective resistance.
Claim 7
Dependent Claim
145 words
Active RC adjustable delay equalizer apparatus having an input terminal and an output terminal comprising: a first operational amplifier having feedback means connected between said amplifier''s input and output; a second operational amplifier having feedback means connected between said amplifier''s input and output; a first slideably adjustable resistive Tau network connecting said first amplifier output and the input of said second amplifier; a third operational amplifier having feedback means connected betweeN said amplifier''s input and output, said output connected to said equalizer output terminal and resistively connected to the input of said first amplifier, and said input resistively connected to the output of said second amplifier; a second slideably adjustable resistive Tau network connecting the input and output of said second amplifier to said equalizer input terminal; and resistive circuit means coupling said equalizer input terminal to the inputs of said first and third amplifiers.
Claim 8
Dependent Claim
145 words
Active RC adjustable delay equalizer apparatus having an input terminal and an output terminal comprising: a first operational amplifier having feedback means connected between said amplifier''s input and output; a second operational amplifier having feedback means connected between said amplifier''s input and output; a first slideably adjustable resistive Tau network connecting said first amplifier output and the input of said second amplifier; a third operational amplifier having feedback means connected betweeN said amplifier''s input and output, said output connected to said equalizer output terminal and resistively connected to the input of said first amplifier, and said input resistively connected to the output of said second amplifier; a second slideably adjustable resistive Tau network connecting the input and output of said second amplifier to said equalizer input terminal; and resistive circuit means coupling said equalizer input terminal to the inputs of said first and third amplifiers.
Claim 9
Dependent Claim
35 words
The equalizer as defined in claim 4 wherein at least one of said resistive T-networks further comprises: a first fixed resistive leg; a second slideably adjustable resistive leg; and a third slideably adjustable resistive leg.
Claim 10
Dependent Claim
23 words
The equalizer as defined in claim 4 wherein at least one of said adjustable resistive networks exhibits a geometric variation in effective resistance.
Claim 11
Dependent Claim
116 words
An adjustable delay equalizer having first, second, and third feedback operational amplifiers, an input terminal and an output terminal, comprising: a first adjustable resistive Tau network connecting the output of said first amplifier and the input of said second amplifier, the output of said second amplifier resistively connected to the input of said third amplifier, the output of said third amplifier connected to said equalizer output terminal and resistively connected to the input of said first amplifier; a second adjustable resistive Tau network connecting the input and output of said second amplifier to said equalizer input terminal; and first resistive circuit means connecting said equalizer input terminal to the inputs of said first and third amplifiers.
Claim 12
Dependent Claim
116 words
An adjustable delay equalizer having first, second, and third feedback operational amplifiers, an input terminal and an output terminal, comprising: a first adjustable resistive Tau network connecting the output of said first amplifier and the input of said second amplifier, the output of said second amplifier resistively connected to the input of said third amplifier, the output of said third amplifier connected to said equalizer output terminal and resistively connected to the input of said first amplifier; a second adjustable resistive Tau network connecting the input and output of said second amplifier to said equalizer input terminal; and first resistive circuit means connecting said equalizer input terminal to the inputs of said first and third amplifiers.
Claim 13
Dependent Claim
35 words
The equalizer as defined in claim 7 wherein at least one of said resistive T-networks further comprises: a first fixed resistive leg; a second slideably adjustable resistive leg; and a third slideably adjustable resistive leg.
Claim 14
Dependent Claim
23 words
The equalizer as defined in claim 8 wherein at least one of said adjustable resistive T-networks exhibits a geometric variation in effective resistance.
Claim 15
Dependent Claim
123 words
An adjustable delay equalizer having first, second, and third feedback amplifiers, an input terminal and an output terminal, comprising: a first slideably adjustable resistive T-network connecting the output of said first amplifier and the input of said second amplifier, the output of said second amplifier resistively connected to the input of said third amplifier, the output of said third amplifier connected to said equalizer output terminal; a second slideably adjustable resistive T-network connecting the input and output of said second amplifier to said equalizer input terminal; first resistive circuit means connecting said equalizer input terminal to the inputs of said first and third amplifiers; and second resistive circuit means connecting the output of said third amplifier and the input of said first amplifier.
Claim 16
Dependent Claim
123 words
An adjustable delay equalizer having first, second, and third feedback amplifiers, an input terminal and an output terminal, comprising: a first slideably adjustable resistive T-network connecting the output of said first amplifier and the input of said second amplifier, the output of said second amplifier resistively connected to the input of said third amplifier, the output of said third amplifier connected to said equalizer output terminal; a second slideably adjustable resistive T-network connecting the input and output of said second amplifier to said equalizer input terminal; first resistive circuit means connecting said equalizer input terminal to the inputs of said first and third amplifiers; and second resistive circuit means connecting the output of said third amplifier and the input of said first amplifier.
Claim 17
Dependent Claim
35 words
The equalizer as defined in claim 10 wherein at least one of said resistive T-networks further comprises: a first fixed resistive leg; a second slideably adjustable resistive leg; and a third slideably adjustable resistive leg.
Claim 18
Dependent Claim
23 words
The equalizer as defined in claim 11 wherein at least one of said adjustable resistive T-networks exhibits a geometric variation in effective resistance.
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) | 1976-02-06 | 1976-08-07 | 1977-02-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-06 | 1980-08-07 | 1981-02-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-06 | 1984-08-07 | 1985-02-06 | $7700.00 | Window Closed / Lapsed |