Na-abawanye nke integrated circuit mmepụta ịmafe ọsọ na PCB mbadamba density, Signal Integrity has become one of the issues that must be concerned in high-speed digital PCB design. The parameters of components and PCB board, the layout of components on PCB board, the wiring of high-speed Signal line and other factors, Can cause problems with signal integrity.

For PCB layouts, signal integrity requires a board layout that does not affect signal timing or voltage, while for circuit wiring, signal integrity requires termination elements, layout strategies, and wiring information. Ọsọ mgbama dị elu na PCB, ntinye ezighi ezi nke akụkụ njedebe, ma ọ bụ wiwi na-ezighi ezi nke akara ọsọ dị elu nwere ike ịkpata nsogbu iguzosi ike n’ezi ihe, nke nwere ike ime ka sistemụ wepụta data na-ezighi ezi, sekit na-arụ ọrụ na-ekwesịghị ekwesị ma ọ bụ na ọ naghị arụ ọrụ ma ọlị. Olee otú iji mgbaàmà iguzosi ike n’ezi ihe n’ime zuru echiche na-irè akara jikoro na PCB imewe aghọwo a na-ekpo ọkụ isiokwu na PCB imewe ụlọ ọrụ.

Signal integrity Problem Good signal integrity means that the signal can respond with the correct timing and voltage level values when required. N’aka nke ọzọ, mgbe mgbama azaghị nke ọma, enwere nsogbu iguzosi ike n’ezi ihe. Nsogbu iguzosi ike n’ezi ihe mgbaàmà nwere ike bute ma ọ bụ bute ozugbo na mgbagha mgbaama, mperi oge, data na-ezighi ezi, ahịrị adreesị na njikwa, yana arụrụ ọrụ sistemu, ma ọ bụ ọbụna mkpọka sistemụ. N’ime usoro imepụta PCB, ndị mmadụ achịkọbara ọtụtụ iwu imebe PCB. Na PCB imewe, mgbaàmà iguzosi ike n’ezi ihe nke PCB nwere ike mma nweta site na-akpachara anya na-ezo aka ndị a imewe iwu.

Mgbe anyị na -emebe PCB, anyị kwesịrị ibu ụzọ ghọta ozi nhazi nke bọọdụ sekit niile, nke gụnyere:

1. The number of devices, device size, device package, chip rate, whether PCB is divided into low speed, medium speed and high speed area, which is the interface input and output area;

2. The overall layout requirements, device layout location, whether there is a high power device, chip device heat dissipation special requirements;

3. Ụdị akara akara, ntụgharị ọsọ na nnyefe, njikwa ihe mgbochi nke akara akara, ụgbọ ala ụgbọ ala na ọnọdụ ịnya ụgbọ ala, isi akara na usoro nchebe;

4. Ụdị ọkụ eletrik, ụdị ala, ihe ndị chọrọ nkwụsị ụda maka ọkụ eletrik na ala, ntọala na nkewa nke ike na ụgbọ elu ala;

5. Ụdị na ọnụego nke akara elekere, isi iyi na ntụziaka nke akara elekere, ihe ndị chọrọ igbu oge, ihe kachasị ogologo oge chọrọ.

PCB oyi akwa imewe

Mgbe ị ghọtasịrị ozi bụ isi nke bọọdụ sekit, ọ dị mkpa ịtụle ihe achọrọ maka ọnụ ahịa okirikiri sekit na iguzosi ike n’ihe mgbaàmà, wee họrọ ọnụọgụ nke eriri wiring dị mma. At present, the circuit board has gradually developed from single layer, double layer and four layer to more multi-layer circuit board. Multi-layer PCB design can improve the reference surface of signal routing and provide backflow path for signal, which is the main measure to achieve good signal integrity. When designing PCB layering, follow the following rules:

1. Ụgbọ elu ntụaka ga-akacha mma ịbụ ụgbọ elu ala. Enwere ike iji ọkụ ọkụ na ụgbọ elu ala dị ka ụgbọ elu ntụaka, ma ha abụọ nwere ọrụ nchekwa ụfọdụ. Agbanyeghị, mmetụta mkpuchi ụgbọ elu na -enye ike dị ala karịa nke ụgbọ elu ala n’ihi na njiri mara ya dị elu yana nnukwu ọdịiche dị n’etiti ụgbọ elu ike na ọkwa ala.

2. Digital circuit and analog circuit are layered. Ebe ọnụ ahịa imewe kwere, ọ kacha mma ịhazi okirikiri dijitalụ na analog na ọkwa dị iche iche. If must want to arrange in same wiring layer, can use ditch, add earthing line, the method such as dividing line to remedy. Analog na ike dijitalụ na ala ga -ekewapụtaghị, agwakọtakwala.

3. Ntugharị mgbaama igodo nke akụkụ dị n’akụkụ anaghị agafe mpaghara nkewa. Mgbama ga-eme nnukwu aka mgbaama gafee mpaghara ahụ wee mepụta radieshon siri ike. If the signal cable must cross the area when the ground cable is divided, a single point can be connected between the ground to form a connection bridge between the two ground points, and then the cable can be routed through the connection bridge.

4. A ga -enwerịrị ụgbọelu ala zuru oke n’okpuru elu akụrụngwa. A ghaghị ịnọgide na -eguzosi ike n’ezi ihe nke ụgbọ elu ala dị ka o kwere mee maka efere multilayer. A naghị anabatakarị ahịrị mgbaàmà ka ọ na -agba n’ime ụgbọ elu.

5, ugboro dị elu, oke ọsọ, elekere na ahịrị mgbama igodo ndị ọzọ kwesịrị ịnwe ụgbọ elu ala dị n’akụkụ. In this way, the distance between signal line and ground line is only the distance between PCB layers, so the actual current always flows in the ground line directly below the signal line, forming the smallest signal loop area and reducing radiation.

How to design the signal of integrity PCB

PCB layout design

Igodo nke imepụta iguzosi ike n’ezi ihe nke bọọdụ e biri ebi bụ okirikiri nhọrọ ukwuu na wired, nke metụtara ọrụ PCB ozugbo. Prior to layout, the PCB size must be determined to meet the function at the lowest possible cost. Ọ bụrụ na PCB buru oke ibu ma kesaa, eriri nnyefe nwere ike ịdị ogologo, na -ebute mmụba na -abawanye, belata mkpọtụ mkpọtụ, yana ọnụ ahịa na -abawanye. Ọ bụrụ na ejikọta ihe ndị ahụ ọnụ, mkpofu ọkụ adịghị mma, na njikọta crosstalk nwere ike ime na wiwi dị n’akụkụ. Ya mere, nhazi ahụ ga-adabere na nkeji ọrụ nke sekit, mgbe ị na-atụle ndakọrịta electromagnetic, ikpo ọkụ na ihe interface.

Mgbe ị na-edobe PCB nwere akara dijitalụ na analog agwakọta, agwakọtala akara dijitalụ na analog. Ọ bụrụ na njikọta analog na dijitalụ ga-agwakọta, jide n’aka na ị kwụ n’ahịrị kwụ n’ahịrị iji belata nsonaazụ njikọta. A ga-ekewapụ sekit dijitalụ, sekit analọg, na sekit na-emepụta mkpọtụ na bọọdụ sekit, na sekit dị nro kwesịrị ibu ụzọ bubie ya, ma kpochapụ ụzọ njikọ dị n’etiti sekit. Karịsịa, tụlee elekere, tọgharịa ma kwụsị ahịrị, ejikọla ahịrị ndị a na ahịrị mgba ọkụ dị ugbu a, ma ọ bụrụ na akara njikọ njikọ electromagnetic mebiri ngwa ngwa, na -ebute nrụpụta na -atụghị anya ya ma ọ bụ kwụsịtụ ya. The overall layout should follow the following principles:

1. Nhazi okirikiri ọrụ, sekit analog na sekit dijitalụ na PCB kwesịrị inwe nhazi okirikiri dị iche iche.

2. Dịka usoro mgbama sekit ka ịhazi nkeji sekit na -arụ ọrụ, ka mgbaama ahụ wee na -aga idobe otu ụzọ ahụ.

3. Take the core components of each functional circuit unit as the center, and other components are arranged around it.

4. Shorten the connection between high-frequency components as much as possible and try to reduce their distribution parameters.

5. Ngwa ndị na-akpaghasị ngwa ngwa ekwesịghị ịdị nso na ibe ha, ntinye na mmepụta ihe kwesịrị ịdị anya.

How to design the signal of integrity PCB

Imebe wiring PCB

Ekwesịrị ịhazi ahịrị mgbama niile tupu wiwi PCB. First of all, clock line, sensitive signal line, and then high-speed signal line, in order to ensure that this kind of signal through the hole is enough, distribution parameters of good characteristics, and then general unimportant signal line.

Incompatible signal lines should be far away from each other and do not parallel wiring, such as digital and analog, high speed and low speed, high current and small current, high voltage and low voltage. A ga -atụgharị eriri mgbama na ọkwa dị iche iche ka ọ kwụ ọtọ na ibe ya iji belata crosstalk. A na -ahazi ahịrị akara nke ọma dịka ntụzịaka nke mgbaama si dị. Ahịrị mgbama mmepụta nke sekit ekwesịghị ịlaghachi azụ na mpaghara akara ngosi ntinye. High-speed signal lines should be kept as short as possible to avoid interfering with other signal lines. Na okpukpu abụọ, ọ bụrụ na ọ dị mkpa, enwere ike ịgbakwunye waya ala dịpụrụ adịpụ n’akụkụ abụọ nke akara mgbaàmà dị elu. Ekwesịrị ichebe ahịrị elekere niile dị elu na bọọdụ multilayer dịka ogologo ahịrị elekere si dị.

Ụkpụrụ izugbe maka wiring bụ:

1. Dị ka o kwere mee ịhọrọ nchara njupụta njupụta dị ala, yana wiring mgbapụta ka oke ọkpụrụkpụ nwere ike ịdị na -agbanwe agbanwe, na -akwalite mmekorita impedance. Maka sekit rf, nhazi enweghị ezi uche nke ntụzịaka akara, obosara na oghere oghere nwere ike bute nnyonye anya n’etiti ahịrị nnyefe mgbaàmà.

2. Dị ka o kwere mee ka ịzenarị eriri ntinye na ntinye dị n’akụkụ na wiwi dị ogologo. Iji belata crosstalk nke ahịrị mgbaàmà yiri, enwere ike ịbawanye oghere dị n’etiti ahịrị mgbama, ma ọ bụ tinye eriri iche n’etiti ahịrị mgbaàmà.

3. The akara obosara na PCB ga-edo edo na ọ dịghị akara obosara mutation ga-eme. Bend wiring PCB ekwesịghị iji nkuku 90 ogo, kwesịrị iji arc ma ọ bụ 135 degrees n’akuku, ruo ókè o kwere mee iji nọgide na -aga n’ihu nke impedance akara.

4. Minimize the area of the current loop. The external radiation intensity of current-carrying circuit is proportional to the current passing through, the loop area and the square of signal frequency. Reducing the current loop area can reduce the ELECTROMAGNETIC interference of PCB.

5. Dị ka o kwere mee iji belata ogologo waya, mụbaa obosara nke waya ahụ, na -akwalite mbenata impedance nke waya ahụ.

6. N’ihi na mgba ọkụ akara akara, ọnụ ọgụgụ nke SIGNAL PCB wiring na-agbanwe ala n’otu oge kwesịrị ibelata dị ka o kwere mee.