JPH0326667Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electronic circuit using a Zener diode in which the Zener diode element is covered with a transparent or semi-transparent case applied to various audio equipment and the like.

[Conventional technology]

A Zener diode has the property that when the reverse voltage reaches a certain value, the reverse current increases rapidly, and the voltage is kept at a constant value over a wide range of current. Figure 2 shows the characteristics of this Zener diode. As the reverse voltage -V increases, when it reaches a certain value V _Z , the reverse current -I increases rapidly, and from then on this reverse voltage increases. It is maintained at a constant value V _Z without This constant value V _Z is called the Zener voltage and is determined by the specific resistance of the semiconductor used as the material of the Zener diode.

The Zener diode takes advantage of such constant voltage characteristics and is used, for example, as a reference voltage element in a constant voltage power supply circuit as shown in Figure 3, or as a fixed voltage element in an audio amplifier circuit as shown in Figure 4. .

[Problem that the invention attempts to solve]

By the way, when a Zener diode is used in such an electronic circuit, the Zener diode generates noise during operation, which mixes into the circuit signal and causes S/S.
There is a problem in that the N characteristics are deteriorated.

As a countermeasure against this noise, attempts have been made to use a low-noise Zener diode or to connect a noise absorbing capacitor in parallel to the Zener diode, but sufficient effects have not been obtained.

That is, in the former case, a sufficient effect cannot be obtained in a high gain circuit, and in the latter case, the time constant due to the use of a capacitor has a negative effect on the circuit signal.

The present invention was devised in response to these circumstances, and aims to provide an electronic circuit using a Zener diode that improves S/N characteristics.

[Means for solving problems]

To achieve the above object, the present invention provides a Zener diode in which a Zener diode element is covered with a transparent or translucent case, and a light emitting element that irradiates light to the Zener diode element through the surface of the case during operation of the Zener diode. It is characterized by having the following.

[Effect]

During operation of the Zener diode, the light emitting element illuminates the Zener diode element through the case surface, thereby energizing the charges within the semiconductor material and thereby enhancing surface recombination. Therefore, since the influence of noise can be eliminated, the S/N characteristic can be improved.

[Example of idea]

Figure 1 shows an example in which an electronic circuit using the Zener diode of the present invention is applied to an audio amplifier circuit, where Ti is a signal input terminal, To is a signal output terminal, Q ₁ to Q ₇ are transistors, and D is a Diode, Z _D is a Zener diode in which the Zener diode element is covered by a transparent or translucent case, which is commonly used in audio circuits, e.g. glass-sealed Zener diode, R ₁ to
R ₅ is the resistance. A Zener diode Z _D is used to provide a fixed voltage to the bases of transistors Q ₃ and Q ₄ . LA is a lamp, LED
During the operation of the Zener diode _ZD , the light emitting element works to irradiate the Zener diode element through this surface.

The operation of this embodiment will be explained below.

As shown in Figure 2, in the Zener diode Z _D , when a reverse voltage -V is applied up to the Zener voltage V _Z , the reverse current -I increases rapidly, and after that the terminal voltage is maintained at V _Z I, so it remains constant. Operates as a voltage diode. Such constant voltage characteristics utilize the breakdown phenomenon in which the current increases rapidly when a reverse voltage is applied to the PN junction of a Zener diode and a certain critical voltage (Zener voltage V _Z ) is reached.
This can be achieved reversibly within the range where the PN junction is not destroyed by heat generation. The breakdown phenomenon mechanism can be roughly divided into electron avalanche breakdown and Zener breakdown, with the former contributing to breakdown at relatively high voltages, and the latter contributing to breakdown at relatively low voltages.

If there is an abnormal distribution of impurities near the PN junction or if the PN junction is exposed to the outside air,
As the applied electric field becomes stronger, the electric field concentrates in those areas, causing breakdown at a value lower than the normal voltage.

In addition, if dislocations exist in the crystal, a minute breakdown called microplasma occurs in these parts, and one microplasma has two states, current on and off, and the current generates pulse noise. Taking these into consideration, low-noise Zener diodes are designed to minimize the generation of pulsed noise, but as mentioned above, sufficient effects cannot be obtained especially when used in high-gain circuits. That's exactly what I did.

Here, when the light emitting element LA is turned on and light is irradiated to the Zener diode element through the case surface of the Zener diode Z _D , the N
Since energy can be given to electrons within the region, surface recombination can be enhanced. As a result, the leakage current on the surface can be increased, and pulse noise can be reduced, so that the S/N characteristic can be improved especially in a high gain circuit.

Therefore, in the electronic circuit using the Zener diode provided by the present invention, the influence of noise is reduced.

Note that it is also possible to integrate the light emitting element LA and the Zener diode _ZD , which allows the element to be made smaller and more practical.

[Effect of idea]

As described above, according to the present invention, the Zener diode element is irradiated with light through the surface of the Zener diode case where the Zener diode element is covered with the transparent or semi-transparent case, so that the S/N characteristics can be improved. be able to.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an electronic circuit using a Zener diode according to an embodiment of the present invention, FIG. 2 is a characteristic diagram of the Zener diode, and FIGS. 3 and 4 are circuit diagrams of a conventional example. Q ₁ to Q ₇ ... transistor, Z _D ... Zener diode, LA ... light emitting element.

Claims (1)

[Scope of utility model registration request] a Zener diode in which a Zener diode element is covered by a transparent or translucent case;
An electronic circuit using a Zener diode, comprising a light emitting element that irradiates light to the Zener diode element through the surface of the case during operation of the Zener diode.