Science and technology is rapid now among development, the article explains electromagnetism for everybody compatible protect technical explore analyse with circuit, hope to be helped somewhat to everybody.

 

Portable apparatus is faced with a lot of and potential electromagnetism to disturb (EMI)/ radio frequency is disturbed (the risk of RFI) source, like voltage of switch load, power source amplifier of power source of fluctuant, short circuit, thunder, switch, RF is mixed the high frequency noise of power amplifier and clock signal. Accordingly, circuit design and electromagnetism compatibility (the technical level that EMC) designs is mixed to the quality of the product the effect that specifications index will have special key.

 

Electromagnetism interference has two kinds of state normally, namely conducted interference and faze of spoke blackberry lily. Conducted interference is to point to the signal coupling that gets on sth resembling a net of an electrified wire netting through electric medium (disturb) to sth resembling a net of another electrified wire netting. Faze of spoke blackberry lily is to show interference source passes a space its signal coupling (disturb) to sth resembling a net of another electrified wire netting. Because this is right,the research of EMC problem is way of pair of interference sources, coupling, sensitive equipment actually 3 person between the research of the relation. The electromagnetism interference that compatible design is the generation in be aimed at electronic product undertakes electromagnetism optimize a design, make make the product that accords with electromagnetism compatibility standard.

 

Want to have electric field or magnetic field presence only in electronic circuitry, with respect to meeting generation electromagnetism is disturbed. In high speed PCB and systematic design, of high frequency line, integrated circuit bring foot, of all kinds receive plug-in unit to wait to become the radiate that has aerial character possibly to violate a source, can emit electromagnetic wave and affect other system or the regular job of other subsystem inside this system.

 

Compatible design considers electromagnetism to be mixed for economic energy resources improve work efficiency, at present most electron product chooses power supply of switch power source. In the meantime, more and more products also contain digital circuit, so that provide more applied functions. The clock circuit in circuit of switch power source and digital circuit is at present the mainest electromagnetism in electronic product violates a source, they are electromagnetism the main content of compatible design. In the design, need part of an imitate signal part, circuit of high speed number and power supply of noise source DC-DC 3 parts part reasonably, make mutual the signal coupling between is achieved the smallest. The field is set in cloth of parts of an apparatus, the parts of an apparatus with mutual and associated comply with as far as possible close principle, it is better to can be obtained so defy noise result. In addition, printed circuit board in the design of power supply cord and ground wire is the important step that overcomes electromagnetism interference.

 

Because product of a few electrons is insufficient to the consideration of electromagnetism compatibility, cause a product to did not achieve electromagnetism the requirement of compatible standard, redesign what will delay a product greatly to appear on the market time, accordingly, the change of electromagnetism compatibility appears more important. Above all, want to undertake diagnostic to the product according to actual condition, find out interference source and the track that jam each other and means, the basis analyses a result, undertake those who have specific aim rectify and reform. Be like: Arrange wire cable to improve; of ground wire system in order to reduce space coupling; to choose tall conductor and ferromagnetism material to realize electromagnetism screen to wait to disturbing a source to undertake the abate; inside limit is classified. The electromagnetism that all cannot improve a product effectively when these measure is compatible when function, the wiring structure that changes circuit board is the basic measure that solves a problem.

 

The ESD of circuit protects electrostatic discharge (ESD) is the knowledge that the engineer that is engaged in hardware is designed and be being produced must master. Staff of a lot of development often can encounter such situation: The product that develops in the lab, check to be passed completely, but after the client uses period of time, can appear namely unusual appearance, fault rate also is not very tall. Usually, these problems are caused as a result of the reason such as surge concussion, ESD concussion mostly. The assembly in electronic product and in production process, the attaint of the semiconductor chip of more than 25% ascribes to ESD. The wide application as microelectronics technology and electromagnetism environment are more and more complex, people is like electromagnetism to disturb to the electromagnetism field effect of electrostatic discharge (EMI) and electromagnetism compatibility (EMC) problem takes seriously more and more.

 

Circuit design engineer passes a certain quantity of instant voltage to restrain commonly implement (TVS) parts of an apparatus increases protection. Parts of an apparatus of the state that be like solid (diode) , metallic oxide rheostat (the material of other and commutator of MOV) , silicon controlled rectifier, alterable voltage (new polymer parts of an apparatus) , aeriform valve and simple spark gap. As the occurrence of circuit of new generation high speed, the working frequency of parts of an apparatus has risen to GHz from a few KHz, the demand of passive to be being used at the tall size that ESD protects parts of an apparatus is higher and higher also. For example, TVS must answer surge voltage of arrival quickly, 8KV(is achieved in 0.7ns when surge voltage or taller) when peak value, spark or adjust voltage of TVS parts of an apparatus (as parallel as input line) must enough low so that regard an effective voltage as alloter.

 

Now, circuit designs an engineer to use ESD increasingly in design of high frequency circuit to control program. Although the silicon detector of low cost (or rheostat) spark / Qian voltage is very low, but its are high frequency the applied requirement that capacity and leakage current cannot satisfy constant growth. Polymer ESD is restrained implement the attenuation when frequency is as high as 6GHz is less than 0.2dB, almost negligible to the influence of circuit not plan.

 

Electromagnetism is compatible it is the design that protects pair of all electron products with circuit cannot evasive problem. Circuit designs an engineer besides familiar electromagnetism compatible relative standard, the every function module in function of the performance that still needs to consider itself of parts of an apparatus integratedly in the design, parasitism parameter, product, cost and systematic design, optimize through layout wiring, increase go resonance of annulus of Ou capacitance, magnetism bead, magnetism, screen, PCB is restrained wait for measure to ensure EMI is in control limits. When making circuit protect design program, the most important is the technical program that because answer,masters above all and design method, choose correct ESD to protect parts of an apparatus accordingly.

 

 

Electromagnetism compatibility EMC includes the requirement of two respects: It is the electromagnetism that in showing equipment is running a course normally, arises to be in an environment on one hand interference cannot exceed certain bounds to be worth; is to show appliance is right on the other hand the immunity to interference that the electromagnetism interference that in be in an environment, exists has fixed rate, namely electromagnetism sensitivity. As the enthusiastic research of engineers, difficult problem also was captured gradually.

 

The place on put together is narrated, the article already was explain electromagnetism compatible protect technical explore analyse with circuit, believe everybody is compatible to electromagnetism the knowledge that protects technical explore analyse with circuit is more and more thorough, hope the article can have referenced value to each reader.