Isolation circuit

Abstract

The invention provides an isolation circuit which comprises a main isolation capacitor, a second capacitor and a first amplifier, wherein the main isolation capacitor has one end and another end, the other end of the main isolation capacitor is connected to one end of the second capacitor and the input end of the first amplifier, the other end of the second capacitor is connected to a second ground terminal, and the second capacitor and the first amplifier are in a second tube core. Through one or more embodiments of the present invention, high isolation voltage can be achieved, since the circuit and the isolation capacitor are made by CMOS process, the problems of the aging of an optocoupler, the change of performance with temperature and poor electric performance do not exist, so the quality is stable, the service life is long, and the cost is low.

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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