US3753140A
Expired / Lapsed
US
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Equalizing network
Assignee: Wandel and Golterman GmbH and Co
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Filing: 1971-09-07
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Granted: 1973-08-14
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Expires: 1991-09-07
Abstract
Abstract An equalizing network for correcting phase and amplitude distortions is constructed as a four-terminal T-section with the input-side series arm and the shunt arm composed of passive impedance elements and with the output-side series arm constituted by an operational amplifier having its ungrounded output terminal connected to its inverting input terminal through a resistive feedback path. The inverting and noninverting input terminals of the amplifier are connected to the ungrounded network input through respective branches of the passive series arm. A variable capacitance forming part of a series-resonant circuit in the shunt arm, or a variable inductance forming part of a parallel-resonant circuit in one of the branches of the passive series arm, serves for selection of the frequency of maximum attenuation; the magnitude of this attenuation is controlled by an adjustable resistor in the feedback path. Selection of the phase delay is carried out with the aid of two ganged resistors in the shunt arm and in the series branch feeding the noninverting amplifier input, or by means of a single adjustable resistor common to this branch and the shunt arm.
Inventors
- 👤 K Feistel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 20:39
CPC Classifications
H; H03; H03H; H03H11/00; H03H11/02; H03H11/04; H03H11/12; H03H11/126; H03H11/16; H03H11/20; H04; H04B; H04B3/00; H04B3/02; H04B3/04; H04B3/14; H04B3/141
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
225 words
An equalizing network comprising a T-section with a reference terminal, an active input terminal and an active output terminal, a first and a second series arm connected in tandem between said active input terminal and said active output terminal, and a shunt arm connected at one end to said reference terminal; said first series arm and said shunt arm being composed of passive impedance elements; said second series arm consisting essentially of an operational amplifier with a noninverting input and an inverting input, said amplifier being provided with a resistive feedback path between said active output terminal and said inverting input; said first series arm being divided into a first branch terminating at said inverting input and a second branch terminating at said noninverting input, the latter input being connected to the other end of said shunt arm; said passive inpedance elements including a capacitive reactance and an inductive reactance together constituting a resonant circuit; said passive impedance elements further including an ohmic portion of said second branch and an ohmic portion of said shunt arm jointly variable with maintenance of a fixed resistance ratio one of said ohmic portions being in circuit with said inductive reactance, the other of said ohmic portions being in circuit with a fixed supplemental resistor compensating an ohmic component of said inductive reactance with the same ratio Rho .
Claim 2
Dependent Claim
225 words
An equalizing network comprising a T-section with a reference terminal, an active input terminal and an active output terminal, a first and a second series arm connected in tandem between said active input terminal and said active output terminal, and a shunt arm connected at one end to said reference terminal; said first series arm and said shunt arm being composed of passive impedance elements; said second series arm consisting essentially of an operational amplifier with a noninverting input and an inverting input, said amplifier being provided with a resistive feedback path between said active output terminal and said inverting input; said first series arm being divided into a first branch terminating at said inverting input and a second branch terminating at said noninverting input, the latter input being connected to the other end of said shunt arm; said passive inpedance elements including a capacitive reactance and an inductive reactance together constituting a resonant circuit; said passive impedance elements further including an ohmic portion of said second branch and an ohmic portion of said shunt arm jointly variable with maintenance of a fixed resistance ratio one of said ohmic portions being in circuit with said inductive reactance, the other of said ohmic portions being in circuit with a fixed supplemental resistor compensating an ohmic component of said inductive reactance with the same ratio Rho .
Claim 3
Dependent Claim
28 words
A network as defined in claim 1 wherein one of said reactances is adjustable for selecting a frequency of maximum absolute value of the attenuation of the network.
Claim 4
Dependent Claim
24 words
A network as defined in claim 2 wherein said reactances are connected in series in said shunt aim, said adjustable reactance being a capacitance.
Claim 5
Dependent Claim
25 words
A network as defined in claim 2 wherein said rEactances are connected in parallel in one of said branches, said adjustable reactance being an inductance.
Claim 6
Dependent Claim
17 words
A network as defined in claim 4 wherein said one of said branches is said second branch.
Claim 7
Dependent Claim
28 words
A network as defined in claim 1 wherein said jointly variable ohmic portions comprise a pair of ganged resistors in said second branch and in said shunt arm.
Claim 8
Dependent Claim
28 words
A network as defined in claim 1 wherein said variable resistive means comprises a resistor bridged across part of said second branch and part of said shunt arm.
Claim 9
Dependent Claim
35 words
A network as defined in claim 1 wherein said feedback path and said first branch form an ohmic circuit including an adjustable resistance for selecting the magnitude of the maximum absolute attenuation of the network.
Claim 10
Dependent Claim
39 words
A network as defined in claim 8 wherein said feedback path includes a pair of series resistors and switch-over means for selectively connecting said adjustable resistance between either of said active terminals and the junction of said series resistors.
Claim 11
Dependent Claim
18 words
A network as defined in claim 9 wherein said series resistors bear a ratio of Rho : (1+).
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) | 1976-08-13 | 1977-02-12 | 1977-08-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-13 | 1981-02-12 | 1981-08-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-13 | 1985-02-12 | 1985-08-14 | $7700.00 | Window Closed / Lapsed |