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Cancellation circuit for input current of operational amplifier

An operational amplifier and input current technology, which is applied in the direction of amplifier input/output impedance improvement, amplifier improvement to reduce temperature/power supply voltage variation, differential amplifier, etc., can solve the problems of poor application effect of the input stage, and achieve small offset voltage and reduction The effect of low input current and noise

Active Publication Date: 2022-04-05
成都芯翼科技有限公司
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Problems solved by technology

[0005] The object of the present invention is a kind of counteracting circuit of operational amplifier input current, is used to solve the technical problem that the application effect of the input stage of operational amplifier in the prior art is relatively poor

Method used

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  • Cancellation circuit for input current of operational amplifier
  • Cancellation circuit for input current of operational amplifier

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Embodiment

[0033] In order to solve the technical problem in the prior art that the input impedance of the triode as a differential input is difficult to achieve close to "infinity", which limits the practical application of the triode as the input stage of the operational amplifier, the embodiment of the present application provides a A canceling circuit for the input current of an operational amplifier, the circuit sets a triode as a differential pair tube at the input stage of the operational amplifier, and a current canceling circuit is set on one side of the differential pair tube, which is used to control the base current of the differential pair tube Offset, thereby greatly reducing the input current of the differential input stage, so that the input impedance of the operational amplifier approaches infinity while maintaining the advantages of low noise and low offset voltage of the differential input pair of the triode.

[0034] Such as figure 1 with figure 2 As shown, in the f...

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Abstract

The invention discloses a counteracting circuit for input current of an operational amplifier. The counteracting circuit comprises a differential input stage, an input current counteracting circuit and an output stage, a first end of the differential input stage is connected with a first end of the input current offset circuit and then connected to a positive and negative input end, a second end of the differential input stage is connected with a second end of the input current offset circuit and then connected to a power supply, and a third end of the differential input stage is connected with a third end of the input current offset circuit and then connected to a bias voltage. The fourth end of the differential input stage is grounded after being connected with the fourth end of the input current offset circuit; the fifth end of the differential input stage is connected with the first end of the output stage, and the second end of the output stage is connected to a voltage output end. According to the operational amplifier, the input current of the differential input stage is greatly reduced, and the input impedance of the operational amplifier approaches to infinity.

Description

technical field [0001] The invention belongs to the technical field of power electronics, and in particular relates to an offset circuit for input current of an operational amplifier. Background technique [0002] Operational amplifiers are widely used in various electronic circuits or integrated circuits, and operational amplifiers play a very important role as the basic core device in different electronic products. Operational amplifiers are used in a variety of circuits, and different application scenarios will "idealize" the common parameters of operational amplifiers, such as idealizing its input resistance as infinite and idealizing its output resistance as very small, The input offset voltage is idealized to be zero. [0003] However, these idealized parameters are difficult to realize in practice, because the input stage of the operational amplifier is usually provided with a triode (bipolar) type differential input pair or a MOSFET type differential input pair. Am...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03F3/45H03F1/30H03F1/26H03F1/56
Inventor 洪锋明
Owner 成都芯翼科技有限公司
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