Oscillators – With distributed parameter resonator
Reexamination Certificate
2000-07-10
2001-06-05
Grimm, Siegfried H. (Department: 2817)
Oscillators
With distributed parameter resonator
C331S10800D, C331S1170FE, C331S17700V
Reexamination Certificate
active
06242987
ABSTRACT:
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The invention relates to an oscillator structure having at least one oscillator circuit and at least one resonator.
Oscillators are electronic oscillation generators, i.e. circuits for producing electrical oscillations. The electrical oscillations generally have a sinusoidal waveform. However, a different waveform, for example in the form of a square, sawtooth, triangular or delta shape, is also possible. The oscillators contain an amplifier and at least one feedback device. An effect produced by the feedback device is that part of an output signal from the amplifier is fed back to its input.
A multiplicity of electronic devices contain an oscillator. Besides signal generators, function generators and pulse generators, transmitters and receivers in the radiofrequency to microwave range are of particular interest.
An oscillator structure of that generic type may, in particular, be a VCO (voltage controlled oscillator), which is stabilized by a resonator.
A special feature of a VCO is that its frequency can be controlled by a voltage applied to it. The oscillator is stabilized by using a resonator. VCOs are suitable both for logic circuits and for radiofrequency applications. When used in the radiofrequency range, an oscillatory response can be tuned by a varactor diode, for example. That allows the oscillator structure to be used in the gigahertz range.
The known oscillator structures have proved themselves in many different ways in practice. However, the large dimensions of the oscillator structure are a disadvantage.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide an oscillator structure having at least one oscillator circuit and at least one resonator, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type, which takes up as little volume as possible and which can be integrated into a housing.
With the foregoing and other objects in view there is provided, in accordance with the invention, an oscillator structure, comprising a conductive support; at least one oscillator circuit disposed on the conductive support; and at least one resonator formed by an exposed electrical conductor disposed below the oscillator circuit.
Thus, the invention provides for the oscillator structure to be constructed in such a way that the oscillator circuit and the resonator are physically isolated from one another. This allows the oscillator circuit to have the smallest possible dimensions and, at the same time, means that a resonator of sufficient size for the necessary electrical properties can be produced.
A reduction in the space requirement for the oscillator structure is achieved by the resonator being situated within a support for the oscillator circuit and/or being a constituent part of that support.
The result of placing the oscillator circuit on a support which already contains the resonator is that the dimensions of the oscillator structure can be kept very small.
Whereas the resonator is made of an electrically conductive material, the support can be conductive or nonconductive. The term support should in no way be understood as being restrictive. In particular, it should be understood as meaning any mount or base for the oscillator circuit.
The support can also be formed by a film, for example. In this case, the conductor is expediently formed by a metalization layer applied to the film. Such a metalization layer can also be used if the support is made from a plastic or ceramic substrate.
The support may also be made from a metal and may be in the form of a punched sheet-metal strip (lead frame), for example.
The invention also refers, in particular, to the integration of the oscillator structure on the support in a housing, in particular as a component.
In this case, the support is disposed in a housing plane, preferably in a lower region of the housing. The oscillator circuit is situated on this support.
A further reduction in the necessary space can be achieved by the conductive support part situated below the oscillator circuit containing at least one electrical conductor.
In accordance with another feature of the invention, the electrical conductor has a strip shape. Other structures of the electrical conductor, such as a meander shape or a spiral shape, are also expedient, with the selected shape being matched to the frequency.
The construction of the electrical conductor as an exposed part of a conductive support, which is connected to the support at one end, has the particular advantage of permitting a part of the support surface which is below the oscillator circuit to be used directly for forming an electrical resonant circuit. In this case, in an electrical equivalent circuit diagram, the exposed conductor represents an inductor, defined by the mechanical dimensions of the conductor, with a resistor connected in parallel. Preferably, the electrical conductor is connected to a ground potential at one point. This is done, by way of example, through the support, which is preferably constructed as a support surface. At another point, the electrical conductor is electrically connected to a capacitance.
In accordance with a further feature of the invention, in order to improve the electrical properties further, one end of the preferably strip-shaped electrical conductor is disposed on the support, and the other end of the electrical conductor is used as a coupling point for inputting or outputting an electrical signal.
In accordance with an added feature of the invention, the electrical conductor is situated essentially within a conductive support surface. Such a configuration has the advantage of reducing the influence of external interference fields to a large extent.
In accordance with an additional feature of the invention, a further reduction in the space requirement can be achieved if the oscillator circuit is formed by an integrated electronic circuit.
In accordance with yet another feature of the invention, the integrated electronic circuit contains at least one varactor diode.
A varactor diode is a surface-contact diode with a pn junction at which a depletion layer is formed that can be varied by using a control voltage in the reverse direction. The insulating depletion layer forms a capacitor with the conductive covering surfaces. The capacitor has a surface which remains constant and a plate spacing that can be changed by using the control voltage. A varactor diode is preferably distinguished by a large ratio between the largest and the smallest useful capacitance, a low series resistance and therefore a high quality. Due to the use of a varactor diode device, the integrated electronic circuit contains a voltage-controlled, variable capacitor. This controls the natural frequency of the resonator.
The varactor diode can be formed from various basic materials. Besides silicon, which is particularly easy to handle in technological terms, gallium arsenide is particularly suitable for high frequencies. With gallium arsenide, the mobility of the charge carriers is approximately four times greater than in silicon and the series resistance of the varactor diode is correspondingly lower.
In accordance with yet a further feature of the invention, there is provided an amplifier for exciting the electrical oscillation. The amplifier can be disposed at any desired point, but it is a particularly expedient feature that the amplifier is incorporated into the integrated electronic circuit.
In accordance with yet an added feature of the invention, the amplifier is incorporated together with the varactor diode.
In principle, the oscillator circuit, which is preferably formed by an integrated electronic circuit, may be mechanically connected to the support in any desired manner. However, in accordance with yet an additional feature of the invention, the integrated electronic circuit is connected to the support through the use of an adhesive layer. A connection using an adhesive layer has a number of advantages. Such a connection is very simple to pro
Lohninger Gerhard
Musiol Lothar
Schopf Klaus-Jurgen
Greenberg Laurence A.
Grimm Siegfried H.
Infineon - Technologies AG
Lerner Herbert L.
Stemer Werner H.
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