Isolating circuit

Abstract

The invention provides an isolating circuit. The isolating circuit comprises a primary isolating capacitor, a second capacitor, a secondary isolating capacitor, a fourth capacitor, and an amplifier, wherein the second end of the primary isolating capacitor is connected to the first end of the second capacitor and the input end of the amplifier; the second end of the secondary isolating capacitor is connected to the first end of the fourth capacitor and the input end of the amplifier; the second end of the second capacitor and the second end of the fourth capacitor are commonly connected to a grounding end; the inputs of the first end of the primary isolating capacitor and the first end of the secondary isolating capacitor are in phase reversal; and the second capacitor, the fourth capacitor and the amplifier are in a second tube core. Through one or more implementation ways of the invention, relatively high isolating voltage can be realized, and the problems that the opto-coupler is aged, the performance is changed along the temperature, and the electric performance is bad are avoided since the circuit and the isolating capacitor are made from the CMOS process; therefore, the isolating circuit disclosed by the invention is stable in quality, long in life and low in cost.

Description

technical field [0001] The present invention relates to the field of circuits, and more particularly, to an isolation circuit in the field of high-voltage circuits. Background technique [0002] An optocoupler is a device that transmits signals through light as a medium. Usually, the light emitter and the receiver (photosensitive semiconductor tube) are packaged in the same package. When a current signal is applied to the input end, the light emitter emits light, and the receiver generates photocurrent after receiving the light, and outputs it from the output end, thereby realizing the "electricity-optical-electricity" conversion. The optocoupler is a photocoupler that uses light as a medium to couple the input signal to the output. The optocoupler is a technology fifty years ago. It is the first time to realize signal isolation by a device. It has been widely used in power control circuits. application. [0003] However, the disadvantage of the optocoupler is that because...

AI Technical Summary

Problems solved by technology

[0003] However, the disadvantage of the optocoupler is that because the electrical properties of the light-emitting diode vary with temperature, the electrical properties of the optocoupler vary with temperature and are unstable.

In addition, because the light-emitting diode and the isolated plastic have aging problems, the optocoupler isolator also has performance aging problems

Furthermore, the optocoupler also has the problem of low common-mode rejection ratio, because there is a parasitic capacitance between the light-emitting diode and the receiving circuit. When there is a large common-mode voltage change on both sides, such as 30kV / us, the current of the parasitic capacitance will be reduced. Let the light-emitting diode glow to cause misoperation

Finally, based on the principle of optocouplers, there are disadvantages such as low speed, high power consumption, and not easy to integrate.

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