Current linear control circuit for constant current source

Abstract

The invention discloses a current linear control circuit for a constant current source. the circuit comprises a triode Q1, a first field effect transistor U1, a second field effect transistor U2, an operational amplifier U3, a first resistor R1, a second resistor R2 and a third resistor R3. The output end of the operational amplifier is connected with the grids of the two field effect transistors, and then the sources of the two field effect transistors are connected with the second input end of the operational amplifier. In this way, a closed-loop negative feedback is formed. Through adjusting the voltage of a third network node and applying a high level on a first network node, a second network node is enabled to output a current of a certain value. In this way, the current linear adjustment of the current source is realized. The current value is convenient to adjust and stable in adjustment process, while the sudden rapid change of the circuit is avoided. Through arranging the above two field effect transistors, the current is prevented from getting too large to damage electrical devices. The circuit is high in safety, stable in performance, simple in design, low in cost and wide in application range, so that the circuit can be widely applied to simple constant current sources.

Description

Technical field: [0001] The invention belongs to the technical field of constant current source circuits, and in particular relates to a current linear control circuit for constant current sources. Background technique: [0002] The constant current source circuit is the basis to be able to provide a stable current to ensure the stable operation of other circuits. The constant current source circuit is mainly composed of an input stage and an output stage, the input stage provides a reference current, and the output stage outputs the required constant current. That is to say, the constant current source circuit is required to output a constant current, so the device as the output stage should have a volt-ampere characteristic of a saturated output current. It is usually implemented by using BJT or MOSFET working in the output current saturation state. There are two types of constant current sources, one is imported high-precision source meters such as Agilent's B2911A, Adv...

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Problems solved by technology

[0004] For this reason, the technical problem to be solved by the present invention lies in the current linear control circuit used in the constant current source in the prior art, which is inconvenient to adjust, and it is easy to cause sudden and rapid changes in the circuit during the adjustment process, and the electric device is easily damaged when the current is too large , the security is poor, so a current linear control circuit for constant current source is proposed

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