Patent US4087737A successfully refreshed from Google Patents.
US4087737A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Phase shifting circuit
Assignee: AT&T Inc
•
Filing: 1977-04-18
•
Granted: 1978-05-02
•
Expires: 1997-04-18
Abstract
Abstract A phase shifting circuit of the type comprising an operational amplifier with a capacitor in its negative feedback path and a resistor in series with its inverting input port is modified to provide adjustable phase shift. Adjustability is achieved by connecting a second capacitor in shunt with the resistor and, furthermore, a series-connected third capacitor and signal-inverting, controllable-gain amplifier also in shunt with the resistor.
Inventors
- 👤 Cosmo Henry De Gennaro
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 14:47
CPC Classifications
H; H03; H03H; H03H11/00; H03H11/02; H03H11/16; H03H11/20; H03G; H03G1/00; H03G1/0005; H03G1/0017
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
82 words
In a phase shifting circuit of the integrating circuit type comprising an operational amplifier having a capacitor connected between its output and inverting input ports and a resistor connected between an input terminal and said inverting input port, an improvement characterized in that, a parallel network is connected in shunt with said resistor, wherein said network comprises a first capacitor connected in series in one branch and a signal-inverting, controllable-gain amplifier and a second capacitor connected in series in a second branch.
Claim 2
Dependent Claim
82 words
In a phase shifting circuit of the integrating circuit type comprising an operational amplifier having a capacitor connected between its output and inverting input ports and a resistor connected between an input terminal and said inverting input port, an improvement characterized in that, a parallel network is connected in shunt with said resistor, wherein said network comprises a first capacitor connected in series in one branch and a signal-inverting, controllable-gain amplifier and a second capacitor connected in series in a second branch.
Claim 3
Dependent Claim
68 words
In a phase shifting circuit of the integrating circuit type comprising an operational amplifier having a capacitor connected between its output and inverting input ports and a resistor connected between an input terminal and said inverting input port, an improvement characterized in that, a capacitor is connected in shunt with said resistor, and a series-connected capacitor and signal-inverting, controllable-gain amplifier are also connected in shunt with said resistor.
Claim 4
Dependent Claim
68 words
In a phase shifting circuit of the integrating circuit type comprising an operational amplifier having a capacitor connected between its output and inverting input ports and a resistor connected between an input terminal and said inverting input port, an improvement characterized in that, a capacitor is connected in shunt with said resistor, and a series-connected capacitor and signal-inverting, controllable-gain amplifier are also connected in shunt with said resistor.
Claim 5
Dependent Claim
92 words
In a summing network comprising an operational amplifier having a capacitor connected between the output and inverting input ports of said operational amplifier, and first, second and third impedance paths connected between first, second and third terminals, respectively, and said inverting input port, an improvement characterized in that, said first path comprises a series-connected resistor, said second path comprises a series-connected capacitor, said third path comprises a signal-inverting, controllable-gain amplifier and a capacitor connected in series, and said first, second and third terminals are connected together to form a common input terminal.
Claim 6
Dependent Claim
92 words
In a summing network comprising an operational amplifier having a capacitor connected between the output and inverting input ports of said operational amplifier, and first, second and third impedance paths connected between first, second and third terminals, respectively, and said inverting input port, an improvement characterized in that, said first path comprises a series-connected resistor, said second path comprises a series-connected capacitor, said third path comprises a signal-inverting, controllable-gain amplifier and a capacitor connected in series, and said first, second and third terminals are connected together to form a common input terminal.
Claim 7
Dependent Claim
100 words
A phase shifting circuit comprising an operational amplifier having an inverting input port and an output port, a first capacitor connected in series between said amplifier inverting input and output ports, a circuit input terminal, a resistor connected in series between said circuit input terminal and said amplifier inverting input port, a second capacitor connected in series between said circuit input terminal and said amplifier inverting input port, a signal-inverting, controllable-gain amplifier, a third capacitor, and means connecting said signal-inverting, controllable-gain amplifier and said third capacitor in series between said circuit input terminal and said operational amplifier inverting input port.
Claim 8
Dependent Claim
100 words
A phase shifting circuit comprising an operational amplifier having an inverting input port and an output port, a first capacitor connected in series between said amplifier inverting input and output ports, a circuit input terminal, a resistor connected in series between said circuit input terminal and said amplifier inverting input port, a second capacitor connected in series between said circuit input terminal and said amplifier inverting input port, a signal-inverting, controllable-gain amplifier, a third capacitor, and means connecting said signal-inverting, controllable-gain amplifier and said third capacitor in series between said circuit input terminal and said operational amplifier inverting input port.
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) | 1981-05-01 | 1981-10-31 | 1982-05-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-05-01 | 1985-10-31 | 1986-05-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-05-01 | 1989-10-31 | 1990-05-02 | $7700.00 | Window Closed / Lapsed |