US3829795A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Crystal oscillator using field effect transistors in an integrated circuit
Assignee: Boeing North American Inc
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Filing: 1973-06-18
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Granted: 1974-08-13
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Expires: 1993-06-18
Abstract
Abstract A crystal controlled oscillator circuit including a constant current source which supplies current to a field effect transistor which amplifies an input signal to provide an output signal to a load which includes a crystal in a feedback path to an input terminal. A bias circuit is connected to the gate electrode of the field effect transistor amplifier.
Inventors
- 👤 J Minney
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 20:07
CPC Classifications
H; H03; H03B; H03B5/00; H03B5/30; H03B5/32; H03B5/36; H03B5/364; H03K; H03K3/00; H03K3/02; H03K3/353; H03K3/354; H03K3/3545
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
295 words
A crystal oscillator circuit using a plurality of field effect transistors, each of said field effect transistors having at least source, drain and gate electrodes, said source and drain electrodes defining a conduction path therebetween, said gate electrode controlling the conduction through said conduction path, said oscillator circuit comprising, a bias network comprising at least two field effect transistors having the conduction paths thereof connected in electrical series for establishing a bias voltage level at a connection between the series connected conduction paths of said field effect transistors, an amplifier field effect transistor having the gate electrode thereof connected to said connection of said bias network to thereby receive said bias voltage level, a substantially constant current source connected to the conduction path of said amplifier field effect transistor to supply a substantially constant current thereto, and a crystal connected as a feedback path around said amplifier field effect transistor, said substantially constant current source comprising a field effect transistor circuit including a first field effect transistor having the conduction path thereof connected in electrical series between a first voltage level and the conduction path of said amplifier field effect transistor, a feedback capacitor connected between the gate electrode of said first field effect transistor and a common point between said first field effect transistor and said amplifier field effect transistor, and a second field effect transistor having the conduction path thereof connected between said first voltage level and the gate electrode of said first field effect transistor, said second field effect transistor providing charge current to said feedback capacitor whereby voltage levels fed back from said common point to said gate electrode control the conduction of said first field effect transistor for providing a substantially constant current source to said amplifier field effect transistor.
Claim 2
Dependent Claim
295 words
A crystal oscillator circuit using a plurality of field effect transistors, each of said field effect transistors having at least source, drain and gate electrodes, said source and drain electrodes defining a conduction path therebetween, said gate electrode controlling the conduction through said conduction path, said oscillator circuit comprising, a bias network comprising at least two field effect transistors having the conduction paths thereof connected in electrical series for establishing a bias voltage level at a connection between the series connected conduction paths of said field effect transistors, an amplifier field effect transistor having the gate electrode thereof connected to said connection of said bias network to thereby receive said bias voltage level, a substantially constant current source connected to the conduction path of said amplifier field effect transistor to supply a substantially constant current thereto, and a crystal connected as a feedback path around said amplifier field effect transistor, said substantially constant current source comprising a field effect transistor circuit including a first field effect transistor having the conduction path thereof connected in electrical series between a first voltage level and the conduction path of said amplifier field effect transistor, a feedback capacitor connected between the gate electrode of said first field effect transistor and a common point between said first field effect transistor and said amplifier field effect transistor, and a second field effect transistor having the conduction path thereof connected between said first voltage level and the gate electrode of said first field effect transistor, said second field effect transistor providing charge current to said feedback capacitor whereby voltage levels fed back from said common point to said gate electrode control the conduction of said first field effect transistor for providing a substantially constant current source to said amplifier field effect transistor.
Claim 3
Dependent Claim
88 words
The crystal oscillator circuit recited in claim 1 wherein said crystal is connected between the gate electrode of said amplifier field effect transistor and one of the electrodes defining the conduction path of said amplifier field effect transistor. 3. The crystal oscillator circuit recited in claim 1 further including a third field effect transistor having the conduction path thereof connected in electrical parallel with the conduction path of said first field effect transistor for providing current to said amplifier field effect transistor during the initial period of oscillation.
Claim 4
Dependent Claim
85 words
The crystal oscillator circuit recited in claim 3 wherein said oscillator circuit includes an input terminal, an output terminal, phase adjusting circuitry connected between said input and output terminals for adjusting the phase of the oscillating signal to the fundamental oscillating frequency of said crystal, and said input terminal being connected to said connection on said bias network to receive the bias voltage level and said output terminal connected to the common point between said amplifier fiEld effect transistor and said first field effect transistor.
Claim 5
Dependent Claim
91 words
The crystal oscillator circuit recited in claim 1 wherein the bias network comprises field effect transistors having the gate and drain electrodes thereof connected together, and wherein field effect transistors connected between the bias voltage level connection and a first voltage level have a relatively higher impedance than field effect transistors connected between the bias voltage level connection and a second voltage level, whereby the current level through the first recited field effect transistors and the threshold voltage levels of the second recited field effect transistor determine the bias voltage level.
Claim 6
Dependent Claim
77 words
The crystal oscillator circuit recited in claim 5 wherein said bias voltage level connection between said series connected field effect transistors is selected as a function of the threshold voltage level of said amplifying field effect transistor when the oscillator circuit is turned on, the transient signal conditions on the biased gate electrode of said amplifier field effect transistor receives a relatively high amplification for enabling said circuit to oscillate at the fundamental frequency of said crystal.
Claim 7
Dependent Claim
37 words
The combination recited in claim 1 wherein said bias network includes a plurality of field effect transistors connected in electrical series, each of said semiconductor devices connected as a substantially passive device for establishing voltage differences thereacross.
Claim 8
Dependent Claim
18 words
The combination recited in claim 1 wherein said feedback path includes a crystal having established frequency controlling characteristics.
Claim 9
Dependent Claim
33 words
The combination recited in claim 1 wherein said feedback path further includes phase shifting means connected to said crystal to permit adjustment of the phase of the signal produced by said feedback means.
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) | 1977-08-12 | 1978-02-11 | 1978-08-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-08-12 | 1982-02-11 | 1982-08-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-08-12 | 1986-02-11 | 1986-08-13 | $7700.00 | Window Closed / Lapsed |