US3569863A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Twin-t oscillator
Assignee: Nortel Networks Ltd
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Filing: 1968-12-13
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Granted: 1971-03-09
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Expires: 1988-12-13
Abstract
Abstract A twin-T oscillator utilizing positive feedback in which the attenuation through the twin-T feedback network is reduced by unbalancing the components so as to provide a low impedance input side and a high impedance output side, thereby reducing the overgain requirements of the associated amplifier.
Inventors
- 👤 Michael C J Cowpland
- 👤 Harry J Lajeunesse
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 08:45
CPC Classifications
H; H03; H03B; H03B5/00; H03B5/20; H03B5/26
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
195 words
In a twin-T oscillator comprising: a. a phase inversion amplifier having a high-impedance input connection, a low-impedance output connection and a common connection; and b. a twin-T feedback network for determining the frequency of said oscillator, said network for determining the frequency of said oscillator, said network comprising: c. fixed input and output resistances connected in series between the output and input connections respectively; d. a fixed shunt capacitance connected between the junction of the two resistances and the common connection; e. fixed input and output capacitances connected in series between the output and input connections respectively; and f. a shunt resistance, connected between the junction of the two capacitances and the common connection, said resistances and capacitances coacting together to provide a phase inversion through the network at a predetermined frequency; g. the improvement comprising: h. the resistance of said output resistance being at least 1.5 times that of said input resistance; i. the capacitance of said input capacitance being at least 1.5 times that of said output capacitance; and j. the resistance of said input resistance being at least four times that of said shunt resistance, whereby the network has reduced attenuation therethrough.
Claim 2
Dependent Claim
195 words
In a twin-T oscillator comprising: a. a phase inversion amplifier having a high-impedance input connection, a low-impedance output connection and a common connection; and b. a twin-T feedback network for determining the frequency of said oscillator, said network for determining the frequency of said oscillator, said network comprising: c. fixed input and output resistances connected in series between the output and input connections respectively; d. a fixed shunt capacitance connected between the junction of the two resistances and the common connection; e. fixed input and output capacitances connected in series between the output and input connections respectively; and f. a shunt resistance, connected between the junction of the two capacitances and the common connection, said resistances and capacitances coacting together to provide a phase inversion through the network at a predetermined frequency; g. the improvement comprising: h. the resistance of said output resistance being at least 1.5 times that of said input resistance; i. the capacitance of said input capacitance being at least 1.5 times that of said output capacitance; and j. the resistance of said input resistance being at least four times that of said shunt resistance, whereby the network has reduced attenuation therethrough.
Claim 3
Dependent Claim
35 words
An oscillator as defined in claim 1 in which the shunt resistance is variable, whereby the oscillator can be turned over a range of frequencies with substantially no change in the attenuation through the network
Claim 4
Dependent Claim
42 words
An oscillator as defined in claim 2 in which: a. the resistance of the output resistance is equal to twice that of the input resistance, and b. the capacitance of the input capacitance is equal to twice that of the output capacitance.
Claim 5
Dependent Claim
43 words
An oscillator as defined in claim 3 in which: a. the capacitance of the input capacitance and the shunt capacitance are equal, and b. the resistance of the input resistance is between about eight and 20 times that of the variable shunt resistance.
Claim 6
Dependent Claim
66 words
An oscillator as defined in claim 1 which further comprises; a. a further resistance across the input of the amplifier, and in which b. the amplifier utilizes direct current coupled transistors, and c. the input and output resistances are direct current coupled to the amplifier so as to set, in conjunction with the further resistance, the direct current bias for the input transistor of the amplifier.
Claim 7
Dependent Claim
33 words
An oscillator as defined in claim 1 in which the impedance between input connection and the common connection of the amplifier is at least as great as the resistance of said output resistance.
Claim 8
Dependent Claim
21 words
An oscillator as defined in claim 6 in which the attenuation through the twin-T feedback network is less than 25 decibels.
References Cited (Backward Citations)
US2927282A
Cited
US3457526A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-03-08 | 1974-09-07 | 1975-03-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-08 | 1978-09-07 | 1979-03-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-08 | 1982-09-07 | 1983-03-09 | $7700.00 | Window Closed / Lapsed |