Oscillators – Frequency stabilization – Temperature or current responsive means in circuit
Reexamination Certificate
2000-02-17
2001-10-02
Kinkead, Arnold (Department: 2817)
Oscillators
Frequency stabilization
Temperature or current responsive means in circuit
C331S1170FE, C331S1160FE, C331S156000, C331S074000, C331S034000, C331S175000
Reexamination Certificate
active
06297708
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to oscillators, and more particularly, to oscillators that maintain a stabilized frequency over a large temperature range.
BACKGROUND OF THE INVENTION
Oscillators are used in numerous applications where it is desired to have an alternating current with a stable frequency. However, most oscillation circuits are subject to deviation from their nominal output frequency. These frequency deviations can be due to many sources including temperature variations, which can cause frequency drift, and load variations, which can cause frequency pulling.
In attempts to stabilize these frequency deviations, circuits have been developed which use biasing techniques to eliminate frequency drift and/or additional stages to reduce pulling. However, the biasing techniques tend to load down the resonator of the circuit and de-que its performance. Additional stages add to the overall cost and complexity of the oscillator circuit.
U.S. Pat. No. 5,126,699 describes the use of a temperature sensor whose reading is used by a temperature compensation algorithm within a microprocessor to determine what DC value should be added to modulation to maintain a desired oscillator frequency. Clearly, a temperature sensor and a microprocessor adds significant cost.
In view of the above, there is a need for an oscillator circuit that compensates for frequency drift and frequency pulling due to temperature variations and load variations, respectively, without adding significant cost or complexity to the circuit.
SUMMARY OF THE INVENTION
The needs described above are in large measure met by a temperature compensated high performance oscillator of the present invention. The oscillator of the present invention generally comprises a resonating device that is directly coupled to ground and a circuit portion. The circuit portion is operably coupled to the resonating device and includes a first transistor and a second transistor. The first transistor provides DC feedback to the second transistor and enables a temperature independent bias current through said second transistor.
The temperature independent bias current is achieved by utilizing substantially equivalent resistance on the collector and emitter legs of the first transistor. Note that the first transistor also operates as a high-gain output buffer to external loads. The output buffer enables the frequency of oscillation of the oscillator to be substantially independent of the external load. The resonating device may comprise a resonator or a high Q inductor. The direct connection of the resonating device to ground substantially maximizes the loaded Q of the oscillator.
REFERENCES:
patent: 3798578 (1974-03-01), Konishi et al.
patent: 4205263 (1980-05-01), Kawagai et al.
patent: 4565979 (1986-01-01), Fiedziuszko
patent: 4570132 (1986-02-01), Driscoll
patent: 4593256 (1986-06-01), Bickley
patent: 4639690 (1987-01-01), Lewis
patent: 5134371 (1992-07-01), Watanabe et al.
patent: 5166647 (1992-11-01), Riebman
patent: 5268657 (1993-12-01), Estrick et al.
patent: 5345197 (1994-09-01), Riggio, Jr.
patent: 5406201 (1995-04-01), Kiryu et al.
patent: 5604467 (1997-02-01), Matthews
Itron, Inc.
Kinkead Arnold
Patterson Thuente Skaar & Christensen P.A.
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