Patent US1560830A successfully refreshed from Google Patents.
Patent US3731230A successfully refreshed from Google Patents.
US3731230A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Broadband circuit for minimizing the effects of crystal shunt capacitance
Assignee: Motorola Solutions Inc
•
Filing: 1971-12-17
•
Granted: 1973-05-01
•
Expires: 1991-12-17
Abstract
Abstract A crystal controlled oscillator circuit having broadband circuitry for balancing out the effects of the static shunt capacitance of a crystal. A broadband phase inverting network is connected across the crystal to cancel the signal flowing through the crystal as a result of capacitive coupling between the plates. The phase inverting network may include a transformer, a center tapped inductor or a broadband inductance-capacitance network. A capacitor having a capacitance value related to the value of the static shunt capacitance is used in conjunction with the phase inverting network to determine the magnitude of the phase inverted cancellation signal.
Inventors
- 👤 F Cerny
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 21:36
CPC Classifications
H; H03; H03B; H03B5/00; H03B5/30; H03B5/32; H03B5/36; H03B5/362
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
241 words
An electronic crystal controlled overtone oscillator including in combination: a transistor having input, output and common terminals; a piezoelectric crystal having first and second electrodes with a static shunt capacitance therebetween, said piezoelectric crystal having a predetermined fundamental resonant frequency and at least one overtone frequency; a phase inverting positive feedback circuit comprising a first capacitor connected between said output and common terminals of said transistor, an inductor having first and second terminals, said first terminal being connected to said output terminal of said transistor, and a second capacitor connected between said second terminal and said common terminal, said first and second capacitors and said inductor having values selected to provide a 180* phase shift between said first and second terminals of said inductor at a selected frequency corresponding to a predetermined overtone of said piezoelectric crystal, said piezoelectric crystal being connected in a series circuit between said input terminal and the junction of said second capacitor and the second terminal of said inductor; and a balancing circuit including a phase inverting network having first and second junctions and a 180* phase shift and a predetermined amplitude transfer function between said junctions, said first junction being connected to one electrode of said piezoelectric crystal, and a capacitor having a value proportional to the value of said static shunt capacitance and said transfer function connected between said second junction of said phase inverting network and the other electrode of said piezoelectric crystal.
Claim 2
Dependent Claim
241 words
An electronic crystal controlled overtone oscillator including in combination: a transistor having input, output and common terminals; a piezoelectric crystal having first and second electrodes with a static shunt capacitance therebetween, said piezoelectric crystal having a predetermined fundamental resonant frequency and at least one overtone frequency; a phase inverting positive feedback circuit comprising a first capacitor connected between said output and common terminals of said transistor, an inductor having first and second terminals, said first terminal being connected to said output terminal of said transistor, and a second capacitor connected between said second terminal and said common terminal, said first and second capacitors and said inductor having values selected to provide a 180* phase shift between said first and second terminals of said inductor at a selected frequency corresponding to a predetermined overtone of said piezoelectric crystal, said piezoelectric crystal being connected in a series circuit between said input terminal and the junction of said second capacitor and the second terminal of said inductor; and a balancing circuit including a phase inverting network having first and second junctions and a 180* phase shift and a predetermined amplitude transfer function between said junctions, said first junction being connected to one electrode of said piezoelectric crystal, and a capacitor having a value proportional to the value of said static shunt capacitance and said transfer function connected between said second junction of said phase inverting network and the other electrode of said piezoelectric crystal.
Claim 3
Dependent Claim
84 words
An electronic overtone oscillator as recited in claim 1 wherein said inverting network includes a transformer having first and second windings, each having a predetermined number of turns, connected to provide a phase inversion therebetween, said first winding being connected to said first junction and said second winding being connected to said second junction, and wherein said balancing capacitor has a value substantially equal to the static shunt capacitance of said crystal multiplied by the ratio of turns in said first and second windings.
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) | 1976-04-30 | 1976-10-30 | 1977-05-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-30 | 1980-10-30 | 1981-05-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-30 | 1984-10-30 | 1985-05-01 | $7700.00 | Window Closed / Lapsed |