US4661785A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Balanced feedback oscillators
Assignee: ST RESEARCH
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Filing: 1985-05-22
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Granted: 1987-04-28
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Expires: 2005-05-22
Abstract
Abstract The oscillator circuit comprises an amplifier having a pair of inputs, a positive feedback path producing a positive feedback ratio to one of the inputs, and a negative feedback path including a series resonant circuit producing a negative feedback ratio to the other of the inputs. The positive and negative feedback paths are independent such that the current in each of the paths can be adjusted independently. In this manner, a high Q multiplier effect is achieved. Also, the circuit has an output path which is separate from the input path so that a high output signal level can be achieved while maintaining a low current through the series resonant circuit.
Inventors
- 👤 Albert Benjaminson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 17:53
CPC Classifications
H; H03; H03B; H03B5/00; H03B5/30; H03B5/32; H03B5/36; H03B2200/00; H03B2200/0002; H03B2200/0004; H03B2200/0008; H03B2200/0012; H03B2200/006; H03B2200/0098
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
113 words
An oscillator circuit comprising: a differential amplifier having an inverting input and a non-inverting input and having a positive feedback path connected to one of said inputs, a negative feedback path connected to the other of said inputs, and an output path; a series resonant circuit connected in said negative feedback path; and at least one impedance element in said positive feedback path for establishing a feedback ratio sufficient to cause oscillation to occur at the resonant frequency of said series resonant circuit; wherein the negative feedback path is separate from said output path such that the output power of said amplifier can be controlled independently of current in said negative feedback path.
Claim 2
Dependent Claim
113 words
An oscillator circuit comprising: a differential amplifier having an inverting input and a non-inverting input and having a positive feedback path connected to one of said inputs, a negative feedback path connected to the other of said inputs, and an output path; a series resonant circuit connected in said negative feedback path; and at least one impedance element in said positive feedback path for establishing a feedback ratio sufficient to cause oscillation to occur at the resonant frequency of said series resonant circuit; wherein the negative feedback path is separate from said output path such that the output power of said amplifier can be controlled independently of current in said negative feedback path.
Claim 3
Dependent Claim
17 words
An oscillator circuit as claimed in claim 1 wherein said series resonant circuit comprises a piezoelectric crystal.
Claim 4
Dependent Claim
18 words
An oscillator circuit as claimed in claim 2 wherein said crystal has one side connected directly to ground.
Claim 5
Dependent Claim
23 words
An oscillator circuit as claimed in claim 3 wherein said crystal has another side connected to said other input of said differential amplifier.
Claim 6
Dependent Claim
33 words
An oscillator circuit as claimed in claim 1 further including limiting circuit means for varying the feedback ratio of said positive feedback path in response to an output level of said output path.
Claim 7
Dependent Claim
88 words
An oscillator circuit, comprising: a differential amplifier having an inverting input and a non-inverting input having: a positive feedback path producing a positive feedback ratio to one of said inputs; and a negative feedback path including a series resonant circuit producing a negative feedback ratio to the other of said inputs; wherein said positive and negative feedback paths are independent such that the current in each of said paths can be adjusted independently, said paths being adjusted to produce oscillation at the resonant frequency of said resonant circuit.
Claim 8
Dependent Claim
88 words
An oscillator circuit, comprising: a differential amplifier having an inverting input and a non-inverting input having: a positive feedback path producing a positive feedback ratio to one of said inputs; and a negative feedback path including a series resonant circuit producing a negative feedback ratio to the other of said inputs; wherein said positive and negative feedback paths are independent such that the current in each of said paths can be adjusted independently, said paths being adjusted to produce oscillation at the resonant frequency of said resonant circuit.
Claim 9
Dependent Claim
16 words
An oscillator as claimed in claim 6 wherein said series resonant circuit is a piezoelectric crystal.
Claim 10
Dependent Claim
25 words
An oscillator circuit as claimed in claim 7 wherein said piezoelectric crystal has a pair of leads, one of said leads being connected to ground.
Claim 11
Dependent Claim
26 words
An oscillator circuit as claimed in claim 6 wherein said differential amplifier comprises two transistors having respective collectors, and a resonant circuit connected between said collectors.
Claim 12
Dependent Claim
25 words
An oscillator circuit as claimed in claim 6 wherein said positive feedback path comprises a capacitive divider connected between said output and said non-inverting input.
Claim 13
Dependent Claim
32 words
An oscillator circuit as claimed in claim 10 wherein said negative feedback path includes a divider comprising a resistance and said series resonant circuit connected between said output and said inverting input.
Claim 14
Dependent Claim
26 words
An oscillator circuit as claimed in claim 6 wherein said differential amplifier comprises a pair of transistors and an inductor connecting bases of said transistors together.
Claim 15
Dependent Claim
33 words
An oscillator circuit as claimed in claim 6 and further including an amplitude limiting control circuit for controlling the positive feedback ratio in response to the amplitude of a signal on said output.
Claim 16
Dependent Claim
38 words
An oscillator circuit as claimed in claim 13 wherein said limiting control circuit comprises a variable capacitor in said positive feedback path and means to vary the capacitance of said capacitor depending upon the output of said amplifier.
Claim 17
Dependent Claim
18 words
An oscillator circuit as claimed in claim 6 wherein said differential amplifier is an integrated circuit differential amplifier.
Claim 18
Dependent Claim
37 words
An oscillator circuit as claimed in claim 15 wherein said integrated circuit differential amplifier has a low impedance output and said positive feedback path comprises a resistive voltage divider connected between said output and said non-inverting input.
Claim 19
Dependent Claim
17 words
An oscillator circuit as claimed in claim 16 wherein said series resonant circuit comprises a piezoelectric crystal.
Claim 20
Dependent Claim
21 words
An oscillator circuit as claimed in claim 15 further including a second resonant circuit connected between said inverting and non-inverting inputs.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-04-27 | 1990-10-27 | 1991-04-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-04-27 | 1994-10-27 | 1995-04-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-04-27 | 1998-10-27 | 1999-04-28 | $7700.00 | Window Closed / Lapsed |