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Voltage-controlled current source circuit

A technology of voltage-controlled current source and current source, which is applied in the direction of adjusting electrical variables, control/regulation systems, instruments, etc., can solve the problems of transmission voltage amplitude, low variation range, and susceptibility to noise interference, etc., to reduce loss, The effect of smoothing load current and reducing voltage requirements

Active Publication Date: 2016-01-27
NORTH CHINA POWER ENG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0011] Since the output current flows directly through the sense resistor R s , when the output current is large R s The loss and heat on the circuit becomes a problem. If a sampling resistor with a very low resistance value is selected, when the output current is small, the input voltage V i The value is also small, when building a program-controlled current source or connecting with other circuits, the input voltage V i The amplitude and variation range of the transmission voltage are also low, and it is easy to be interfered by noise

Method used

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  • Voltage-controlled current source circuit

Examples

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Effect test

Embodiment 1

[0043] The invention provides a voltage-controlled current source circuit, the basic circuit of which is as figure 2 shown. Including operational amplifiers A1, A2, resistor R 1 , R 2 , R 3 , R 4 , Sampling resistor R s1 and load resistor R L ; The positive and negative input terminals of the operational amplifier A1 are respectively connected to the resistor R 1 and resistor R 3 One end of the connection, the output of the operational amplifier A1 and the sampling resistor R s1 Connected at one end, the resistor R 1 The other end of the resistor R is grounded and the resistor R 3 The other end is connected to the voltage input terminal, the resistor R 2 The two ends of the operational amplifier A1 are respectively connected to the output terminal and the negative input terminal; the positive input terminal of the operational amplifier A2 is connected to the sampling resistor R s1 The other end is connected, and its negative input and output are respectively connec...

Embodiment 2

[0058] image 3 given in figure 2 On the basis of , a follower is connected in parallel to double the output current. and figure 2 Compared to this circuit, only an additional operation amplifier A4 and sampling resistor R s2 The follower composed of it can be seen from the circuit that the output voltage of the operational amplifier A4 always follows V t change by image 3 It can be seen that the flow through the sampling resistor R s1 and R s2 The currents are:

[0059] I s1o =(V t -V o ) / R s1

[0060] I s2o =(V t -V o ) / R s2

[0061] flow through the load resistor R L The current is the sum of the above two currents. It can be seen that the output current is increased after adding the follower; if the operational amplifier A4 and the sampling resistor R s2 Respectively with the operational amplifier A1 and the sampling resistor R s1 With exactly the same parameters, the output current is doubled.

[0062] If a follower and a sampling resistor are added...

Embodiment 3

[0065] Figure 4 given in figure 2 A schematic diagram of a scheme to increase the output voltage based on . exist figure 2 The output of the circuit shown is augmented by a resistor R 10 ~R 12 It is an inverting amplifier composed of operational amplifier A5, and the load is connected between the output Vo+ of the voltage-controlled current source and the output Vo- of the newly added inverting amplifier. In order to avoid the upper and lower limits of the output, the input voltage cannot be directly grounded, and multiple way to ground the level of the control signal, Figure 4 One way of grounding is given, that is, through two resistors R 5 and R 6 The intermediate level of the control input signal is at the same potential as the ground, and of course other level control methods can also be used.

[0066] against Figure 4 The circuit can also be deduced as follows:

[0067] V i+ -V i- = K 1 K 2 (V t -V o+ )

[0068] The output voltage of operational ampl...

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Abstract

The invention discloses a voltage-controlled current source circuit which relates to the field of electronic lines and voltage-controlled current sources. The output end of an operational amplifier A1 is serially connected with a sampling resistor Rs1 and is then output. Two ends of the sampling resistor Rs1 are connected with operational amplifiers A2 and A3 and resistors R7, R8 and R9, thereby forming a signal amplification circuit. The output V4 amplified by the output end of the sampling resistor Rs1 of the sampling circuit is connected with the positive input end of the operational amplifier A1 through a resistor R4. The output V2 amplified by the operational amplifier A1 end of the Rs1 of the amplifying circuit is connected with the negative input end of the operational amplifier A1 through the resistor R2. The positive input end and the negative input end of the operational amplifier A1 are respectively connected with a voltage dividing resistor R3 and a voltage dividing resistor R1. The voltage-controlled current source circuit is realized through an operational amplifier circuit. Based on the current source circuit which is realized by typical operational amplifiers, through increasing the input end which amplifies voltage drop on the current sampling resistor and feeds the amplified voltage drop to the operational amplifier, voltage drop and power consumption of the sampling resistor are reduced, and the input voltage range of the voltage-controlled current source is enlarged.

Description

technical field [0001] The invention relates to the field of electronic circuit and current source, more specifically, relates to a voltage-controlled current source circuit, which mainly completes the conversion from voltage to current and realizes the function of the voltage-controlled current source. Background technique [0002] Voltage-controlled current source or program-controlled current source is an indispensable instrument for electrical measurement, measurement calibration, and electrical test, and is widely used in industrial and mining enterprises and laboratories. [0003] In current source circuits that require relatively high power, power devices such as field effect transistors and Darlington transistors are commonly used to convert voltage to current, and open-loop control methods are often used, so their accuracy is low. In the low-power applications of electronic circuits, operational amplifiers and voltage stabilizing circuit devices are often used to im...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G05F1/575
Inventor 王绍德徐珂朱芸杨正莉康海燕任树东
Owner NORTH CHINA POWER ENG
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