JPS6210715A - Constant electric current source - Google Patents

Abstract

PURPOSE:To improve the temperature characteristic of a constant electric current by making the temperature characteristic of a resistance inserted between gate sources of an electric field effect transistor into the comparatively large positive value. CONSTITUTION:When between gate sources of the electric field effect transistor, the general resistor whose resistance value is 4.2kOMEGA is inserted and the constant electric current of 75muA is obtained at 0 deg.C, the electric current temperature characteristic of the transistor is 94muA at 100 deg.C, namely, shows the electric current increase of +25.3%. This means that each time 1 deg.C advances, the electric current is changed positively to 2,530 PPM only, and is inconvenient as the constant electric current source. Then, by giving the resistance change between gate sources so that the change can come to be the resistance value of 4.2kOMEGA and the resistance value of 5.61kOMEGA an initial electric current 75muA (0 deg.C) is constantly kept. Thus, the stable constant electric current, which is not influenced by the ambient temperature, can be easily and low-pricedly obtained.

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、電界効果トランジスタを用いて一定電流を得
る定電流源に関するものである。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a constant current source that obtains a constant current using a field effect transistor.

〔従来の技術〕[Conventional technology]

電界効果トランジスタのゲート・ソース間に電流制限用
抵抗を入れた定電流回路は、その電流値が大きい場合に
は電流の温度特性が負に大きく変化し、すなわち温度が
上がると電流が減少し、電流値が小さい場合には電流の
温度特性が正に大きく変化する。そして、最適電流値で
は電流の温度特性が零になる領域があることは、公知で
ある。In a constant current circuit in which a current limiting resistor is inserted between the gate and source of a field effect transistor, when the current value is large, the temperature characteristics of the current change significantly negatively, that is, as the temperature rises, the current decreases. When the current value is small, the temperature characteristics of the current change significantly. It is well known that there is a region where the temperature characteristics of the current become zero at the optimum current value.

〔発明が解決しようとする問題点〕[Problem that the invention seeks to solve]

上記のように最適電流値で電流の温度特性が零になるこ
とが分かっていても、実際に必要とする電流値がこの最
適電流値と一致することは稀であるため、実用上不便で
あった。本発明は、ｉ＆″５１４ｘ流値より小さい電流
値においてその定電流の温度特性を改善しようとするも
のである。Even if it is known that the temperature characteristics of the current become zero at the optimum current value as described above, it is still inconvenient in practice because the actually required current value rarely matches this optimum current value. Ta. The present invention seeks to improve the constant current temperature characteristics at current values smaller than the i&''514x current value.

〔問題点を解決するための手段〕[Means for solving problems]

本発明は、電界効果トランジスタのゲート・ソース間に
入れる抵抗の温度特性を正の比較的大きな値とすること
により、定電流の温度特性の改善を可能としたものであ
る。The present invention makes it possible to improve the temperature characteristics of constant current by setting the temperature characteristics of the resistance inserted between the gate and source of a field effect transistor to a relatively large positive value.

〔作用〕[Effect]

上記抵抗の温度特性を正の大きな値とすれば、電流値が
小さい場合、温度上昇と共に電流が増加するのを押さえ
るので、電流の温度特性の変化が小さくなる。If the temperature characteristic of the resistor is set to a large positive value, when the current value is small, the increase in the current as the temperature rises is suppressed, and therefore the change in the temperature characteristic of the current becomes small.

〔実施例〕〔Example〕

第１図は本発明の構成を示す回路図、第２図は本発明の
効果を示す特性比較図、第３図は異なるゲート・ソース
間電圧におけるドレイン電流とドレイン・ソース間電圧
との関係の一例を示す特性図、第４図は異なる温度にお
けるドレイン電流とゲート・ソース間電圧との関係の一
例を示す特性図である。Figure 1 is a circuit diagram showing the configuration of the present invention, Figure 2 is a characteristic comparison diagram showing the effects of the present invention, and Figure 3 shows the relationship between drain current and drain-source voltage at different gate-source voltages. FIG. 4 is a characteristic diagram showing an example of the relationship between drain current and gate-source voltage at different temperatures.

第１図において、Ｄはドレイン、Ｓはソース、Ｇはゲー
ト、Ｒは抵抗を示す。第３図において、■μｓはゲート
・ソース間電圧を表わす。この電圧ｖμｓは抵抗Ｒの値
を変えれば変わる。すなわち、抵抗Ｒの値を変えるとド
レイン電流が変わる。また、第４図において、■Ｄｓは
ドレイン・ソース間電圧、Ｔａは周囲温度を示す、この
例では、ドレイン電流は温度Ｔａの上昇と共に減少して
いる。In FIG. 1, D is a drain, S is a source, G is a gate, and R is a resistance. In FIG. 3, ■μs represents the gate-source voltage. This voltage vμs changes by changing the value of the resistor R. That is, changing the value of the resistor R changes the drain current. Further, in FIG. 4, ■Ds represents the drain-source voltage, and Ta represents the ambient temperature. In this example, the drain current decreases as the temperature Ta rises.

ところで、第１図に示す回路において、電界効果トラン
ジスタのゲート・ソース間に抵抗値が４．２にΩの一般
の抵抗器を入れ０℃で７５μＡの定電流を得るようにし
た場合、そのトランジスタの電流温度特性は、　１００
℃で９４μＡ、すなわち＋２５．３％の電流増加を示し
た。これは、１℃の上昇ごとに電流が２５３０Ｐ　Ｐ　
Ｍだけ正に変化（増加）することであり、定電流源とし
ては不都合である（第２図参照）。By the way, in the circuit shown in Figure 1, if a general resistor with a resistance value of 4.2 Ω is inserted between the gate and source of the field effect transistor to obtain a constant current of 75 μA at 0°C, the transistor The current temperature characteristics of 100
℃ showed a current increase of 94 μA, or +25.3%. This means that for every 1°C rise, the current is 2530P P
This is a positive change (increase) by M, which is inconvenient for a constant current source (see Figure 2).

そこで、この初期電流７５μＡ　　（０℃）を一定に保
つには、０℃で４．２にΩ、１００℃で５．６１４にΩ
の抵抗値となる如き抵抗変化をゲート・ソース間に与え
ればよいことが実験によって確認された。これは、その
抵抗の温度特性が正の３３６７Ｐ　Ｐ　Ｍ　／　’Ｃで
あればよいことを意味する。Therefore, in order to keep this initial current of 75μA (0℃) constant, it is necessary to increase the resistance to 4.2Ω at 0℃ and to 5.614Ω at 100℃.
It has been confirmed through experiments that it is sufficient to apply a resistance change between the gate and the source such that the resistance value becomes . This means that the resistance only needs to have a positive temperature characteristic of 3367P P M /'C.

このような正の温度特性を示す抵抗体は、ニッケル、ニ
ッケル・パラジウム合金、ニッケル・ロジウム合金、鉄
・パラジウム合金、白金・鉄合金などの薄膜抵抗で容易
に得られる。A resistor exhibiting such positive temperature characteristics can be easily obtained using a thin film resistor made of nickel, nickel-palladium alloy, nickel-rhodium alloy, iron-palladium alloy, platinum-iron alloy, or the like.

第２図は、第１図の抵抗Ｒに温度特性が±５０ＰＰＭ／
℃以内の一般の抵抗器を用いた場合と、０℃〜１００℃
間で＋３３６７Ｐ　Ｐ　Ｍ　／　’Ｃの抵抗器を用いた
場合とにおける電流の温度特性を比較したものである。Figure 2 shows that the resistance R in Figure 1 has a temperature characteristic of ±50PPM/
When using a general resistor within ℃ and 0℃ to 100℃
This is a comparison of the temperature characteristics of current when using a +3367PPM/'C resistor.

〔発明の効果〕〔Effect of the invention〕

以上説明したとおり、本発明によれば、抵抗体の温度特
性を適当に選択することにより周囲温度に左右されない
安定な定電流を容易に且つ安価に得ることができ、その
実用的効果は極めて大である。As explained above, according to the present invention, by appropriately selecting the temperature characteristics of the resistor, it is possible to easily and inexpensively obtain a stable constant current that is not affected by the ambient temperature, and its practical effects are extremely large. It is.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は本発明の構成を示す回路図、第２図は本発明の
効果を示す特性比較図、第３図は異なるゲート・ソース
間電圧におけるドレイン電流とドレイン・ソース間電圧
との関係の一例を示す特性図、第４図は異なる温度にお
けるドレイン電流とゲート・ソース間電圧との関係の一
例を示す特性図である。 Ｇ・・・ゲート、Ｓ・・・ソース、Ｄ・・・ドレイン、
Ｒ・・・温度特性が正の比較的大きな値を示す抵抗。 第１図 １道（°Ｃ） ド゛レインソース間電Ｌ＜Ｖン 第３図Figure 1 is a circuit diagram showing the configuration of the present invention, Figure 2 is a characteristic comparison diagram showing the effects of the present invention, and Figure 3 shows the relationship between drain current and drain-source voltage at different gate-source voltages. FIG. 4 is a characteristic diagram showing an example of the relationship between drain current and gate-source voltage at different temperatures. G...gate, S...source, D...drain,
R...Resistance whose temperature characteristics exhibit a relatively large positive value. Fig. 1 (°C) Drain-source voltage L<V Fig. 3

Claims (1)

【特許請求の範囲】[Claims] 電界効果トランジスタのゲート・ソース間に抵抗を入れ
た定電流源において、上記抵抗を温度特性が正の比較的
大きな値を示すものとし、その値を選択することにより
周囲温度が変化してもほぼ一定の電流が得られるように
した定電流源。In a constant current source with a resistor inserted between the gate and source of a field effect transistor, the above resistor should have a relatively large value with a positive temperature characteristic, and by selecting that value, it will remain stable even when the ambient temperature changes. A constant current source that provides a constant current.