JPH04246808A - Tuning circuit - Google Patents

Abstract

PURPOSE:To change a tuning frequency at high speed by a method wherein the state in which the change of magnetic field generated in a core-containing coil is not followed up by the change of coil current, is corrected by the magnetic field generated by a hollow-cord coil. CONSTITUTION:A transient phenomenon, in which an overshoot phenomenon and an undershoot phenomenon are repeated by the effect of current, which is generated by the magnetic field 121 generated by a magnetic field generating circuit 103, generated in the magnetic core of a core-containing coil 102, and it takes a long period of time until the above-mentioned magnetic field is focussed to a fixed magnetic field changing width. In an auxiliary magnetic field generating circuit 107, an auxiliary current source 105 generates the current 111 of a specific time-series pattern which is stored in advance for generation by a hollow coil 106 of magnetic field 122 to be used to correct the transient phenomenon of the core-containing coil 102. As no time delay is generated between the change of coil current and the change of magnetic field by the effect of an eddy current, the magnetic field 122 of the time-series pattern same as the current 111 can be generated.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic field control type tuning circuit mainly used in the SHF band.

0002

2. Description of the Related Art Conventionally, as shown in FIG. 3, this type of tuned circuit has a magnetic field generating circuit 203 composed of a variable current source 201 and a magnetic core coil 202, and a resonant circuit whose resonant frequency changes depending on the strength of the magnetic field. The tuning frequency is changed by changing the current of the variable current source 201.

0003

[Problems to be Solved by the Invention] The conventional tuning circuit described above requires a strong magnetic field for the resonant element used in the circuit, and therefore a magnetic core capable of generating a strong magnetic field is required to generate this magnetic field. An input coil is used.

[0004] In a magnetic core coil, the generated magnetic field generally does not immediately follow changes in the coil current because of the eddy current effect field within the magnetic core in response to changes in the coil current. Further, in response to a step-like change in the coil current, a transient phenomenon occurs in which overshoot and undershoot repeat in the change in the magnetic field, and it takes time to converge.

[0005] Therefore, the conventional tuning circuit has the disadvantage that the tuning frequency cannot be changed at high speed.

[0006]

[Means for Solving the Problems] A tuned circuit of the present invention includes a variable current source, a magnetic field generating circuit having a magnetic core-containing coil into which current from the variable current source flows, and a magnetic field generating circuit having a magnetic core-containing coil into which current from the variable current source flows. an auxiliary current source that generates a predetermined time-series pattern of current in an amount proportional to the amount of change in the current from the variable current source when the variable current source changes; an auxiliary magnetic field generation circuit having an air-core coil into which a current from a current source flows; a resonant element disposed in a magnetic field generated by the auxiliary magnetic field generation circuit and the magnetic field generation circuit and whose resonance frequency changes according to the magnetic field strength; It is equipped with

[0007] A silicon steel plate may be used for the magnetic core of the magnetic core coil, and a YIG crystal may be used for the resonant element.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a waveform diagram of various parts during operation of this embodiment.

In the embodiment shown in FIG. 1, a magnetic field generating circuit 103 is composed of a variable current source 101 and a magnetic core coil 102. For example, silicon steel is used for the magnetic core of the magnetic core coil 102.

Reference numeral 104 denotes a resonant element made of, for example, YIG crystal, whose resonant frequency changes depending on the strength of the magnetic field, and is placed in the magnetic field generated by the magnetic field generating circuit 103.

Reference numeral 107 denotes an auxiliary magnetic field generation circuit, which includes an auxiliary current source 105 that generates a specific time-series pattern of current in an amount proportional to the amount of current change of the variable current source 101 when the current of the variable current source 101 changes; It is composed of an air-core coil 106 placed in the magnetic field generated by the circuit 103.

Next, the operation of this embodiment will be explained.

The current 110 of the variable current source 101 is shown in FIG.
), at time t1 I1 to I2
When the magnetic core coil 102 generates a magnetic field 1
21, that is, the magnetic field 1 generated by the magnetic field generation circuit 103
21 changes from B1 to B2. This change in the magnetic field 121 causes a transient phenomenon of repeating overshoot and undershoot as shown in FIG. 2(b) due to the eddy current effect generated in the magnetic core of the magnetic core coil 102, and the magnetic field changes at a constant width ΔB. It takes a long time (T1) to converge. Here, since the tuning frequency of the resonant element 104 instantaneously follows the magnetic field B, the delay in the change in the magnetic field is equal to the tuning delay.

On the other hand, at this time, in the auxiliary magnetic field generation circuit 107, the auxiliary current source 105 supplies the magnetic field 122 that corrects (cancels) the transient phenomenon of the magnetic core coil 102 to the air-core coil 1.
A current 111 (see FIG. 2(c)) having a specific time-series pattern stored in advance is generated from 06 onwards. Since the air-core coil 106 does not have a time delay between the coil current change and the magnetic field change due to the eddy current effect, the magnetic field 122 has the same time-series pattern as the current 111.
occurs.

With the above operation, the resonant element 104 receives a magnetic field 12 which is a composite of the magnetic field 121 generated by the magnetic field generating circuit 103 and the magnetic field 122 generated by the auxiliary magnetic field generating circuit 107.
3 (see FIG. 2(d)), the transient phenomenon of the magnetic field 121 is corrected and converges to a constant magnetic field change width ΔB in a short time (T2). Very fast, ie short-time, tuning is therefore possible.

Next, the operation when the variation width of the current 110 (this variation width corresponds to the tuning frequency variation width) is changed will be explained.

When the width of change in the current 110 changes, the amount of transient phenomena (amplitudes of overshoot and undershoot) of the magnetic field 121 also changes proportionally. On the other hand, auxiliary current source 1
05 also inputs the output waveform of the variable current source 101 and outputs a corrected current output 111 proportional to the amount of current change of the variable current source 101.
Therefore, regardless of the range of change in the tuning frequency, appropriate corrections can be made constantly and high-speed tuning can be achieved.

[0019]

[Effects of the Invention] As explained above, the present invention uses the magnetic field generated by the air-core coil to compensate for the fact that the change in the magnetic field generated by the magnetic core coil does not immediately follow the change in the coil current. Therefore, there is an effect that the tuning frequency can be changed at high speed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a waveform diagram of each part during operation of the embodiment shown in FIG. 1;

FIG. 3 is a block diagram of a conventional tuning circuit.

[Explanation of symbols]

101 Variable current source 102 Coil with magnetic core 103 Magnetic field generation circuit 104 Resonant element 105 Auxiliary current source 106 Air core coil 107 Auxiliary magnetic field generation circuit

Claims (3)

[Claims] 1. A magnetic field generating circuit having a variable current source, a magnetic core-containing coil into which current from the variable current source flows, and a magnetic field generating circuit that generates a predetermined time series pattern when the current from the variable current source changes. an auxiliary current source that generates current in an amount proportional to the amount of change in the current from the variable current source; and an air-core coil that is placed in the magnetic field generated by the magnetic field generation circuit and into which the current from the auxiliary current source flows. What is claimed is: 1. A tuning circuit comprising: an auxiliary magnetic field generating circuit having a magnetic field generating circuit; and a resonant element having a resonant frequency that is arranged in a magnetic field generated by the auxiliary magnetic field generating circuit and the magnetic field generating circuit and whose resonant frequency changes according to the magnetic field strength. 2. The tuned circuit according to claim 1, wherein a silicon steel plate is used for the magnetic core of the magnetic core-containing coil. 3. The tuning circuit according to claim 1, wherein a YIG crystal is used for the resonant element.