Ndi kuwonjezeka kwa Integrated dera linanena bungwe kusintha liwiro ndi PCB bolodi 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. Kuthamanga kwakukulu kwa chizindikiro pa PCB, kuyika kolakwika kwa zigawo zakumapeto, kapena mawaya olakwika a zizindikiro zothamanga kwambiri kungayambitse mavuto a kukhulupirika kwa chizindikiro, zomwe zingayambitse dongosolo kuti litulutse deta yolakwika, dera ligwire ntchito molakwika kapena kusagwira ntchito konse. Momwe mungatengere kukhulupirika kwazizindikiro ndikuganizira mozama ndikuwongolera magwiridwe antchito pamapangidwe a PCB yakhala nkhani yovuta kwambiri pamakampani opanga ma PCB.

Signal integrity Problem Good signal integrity means that the signal can respond with the correct timing and voltage level values when required. Mosiyana ndi zimenezi, pamene chizindikiro sichikuyankha bwino, pali vuto la kukhulupirika kwa chizindikiro. Mavuto a umphumphu wa chizindikiro angayambitse kapena kubweretsa mwachindunji kusokoneza zizindikiro, zolakwika za nthawi, deta yolakwika, adiresi ndi mizere yolamulira, ndi kusokoneza dongosolo, kapena kuwonongeka kwa dongosolo. M’kati mwa mapangidwe a PCB, anthu adasonkhanitsa malamulo ambiri a PCB. Mu mapangidwe a PCB, kukhulupirika kwa chizindikiro kwa PCB kumatha kukwaniritsidwa bwino potengera malamulo apangidwe awa.

When designing PCB, we should first understand the design information of the whole circuit board, which mainly includes:

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. Mtundu wa mzere wa chizindikiro, liwiro ndi njira yotumizira, zowongolera zowongolera za mzere wa chizindikiro, mayendedwe othamanga mabasi ndi kuyendetsa galimoto, zizindikiro zazikulu ndi njira zotetezera;

4. Mtundu wa magetsi, mtundu wa nthaka, zofunikira zolekerera phokoso lamagetsi ndi nthaka, kukhazikitsa ndi kugawa magawo a magetsi ndi ndege yapansi;

5. Mitundu ndi mitengo ya mizere ya wotchi, gwero ndi njira ya mizere ya wotchi, zofunika kuchedwa kwa wotchi, zofunikira za mzere wautali kwambiri.

PCB layered kapangidwe

Pambuyo pomvetsetsa mfundo zazikuluzikulu za bolodi la dera, m’pofunika kuyeza zofunikira za kayendetsedwe ka kayendetsedwe ka kayendetsedwe ka kayendetsedwe ka kayendetsedwe ka kayendetsedwe ka kayendetsedwe ka kayendetsedwe ka kayendetsedwe ka kayendetsedwe ka kayendetsedwe ka kayendetsedwe ka kayendetsedwe ka kayendetsedwe ka kayendetsedwe ka kayendetsedwe ka kayendetsedwe kake. 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. Ndege yolozerayo iyenera kukhala yoyambira pansi. Both power supply and ground plane can be used as reference plane, and both have certain shielding function. Komabe, chitetezo cha ndege yoperekera mphamvu ndi yotsika kwambiri kuposa ndege yapansi panthaka chifukwa cha mawonekedwe ake apamwamba komanso kusiyana kwakukulu komwe kungathe pakati pa ndege yoperekera mphamvu ndi malo oyambira.

2. Digital circuit and analog circuit are layered. Kumene mtengo wapangidwe umaloleza, ndi bwino kukonza mabwalo a digito ndi analogi pazigawo zosiyana. If must want to arrange in same wiring layer, can use ditch, add earthing line, the method such as dividing line to remedy. Mphamvu za analogi ndi digito ndi nthaka ziyenera kulekanitsidwa, osasakanikirana.

3. Mayendedwe ofunikira a zigawo zoyandikana sadutsa gawo la magawo. Zizindikiro zidzapanga chizindikiro chachikulu chozungulira dera lonse ndikupanga ma radiation amphamvu. 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. Payenera kukhala ndege yathunthu pansi pa chigawocho. Chilungamo cha ndege yapansi chiyenera kusungidwa momwe zingathere pa mbale ya multilayer. Palibe mizere yolumikizira yomwe imaloledwa kuyenda mundege yapansi.

5, ma frequency apamwamba, kuthamanga kwambiri, wotchi ndi mizere ina yofunikira iyenera kukhala ndi ndege yoyandikana nayo. 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

Chinsinsi cha kukhulupirika kwa chizindikiro cha bolodi yosindikizidwa ndi masanjidwe ndi waya, zomwe zimagwirizana mwachindunji ndi magwiridwe antchito a PCB. Prior to layout, the PCB size must be determined to meet the function at the lowest possible cost. Ngati PCB ndi yayikulu kwambiri ndikugawidwa, chingwe chotumizira chikhoza kukhala chachitali kwambiri, zomwe zimapangitsa kuti pakhale kusokoneza, kuchepetsa kukana phokoso, ndi kuwonjezeka kwa mtengo. Ngati zinthuzo zimayikidwa palimodzi, kutaya kwanyengo kumakhala kovuta, ndipo kulumikizana kwa crosstalk kumatha kuchitika pafupi ndi zingwe. Chifukwa chake, masanjidwewo akuyenera kukhazikitsidwa pamagawo ogwirira ntchito a dera, ndikuganiziranso kuyanjana kwa ma elekitirodi, kutayika kwa kutentha ndi mawonekedwe.

Mukayala PCB yokhala ndi ma digito osakanikirana ndi ma analogi, osasakaniza ma digito ndi ma analogi. Ngati ma siginolo a analog ndi digito akuyenera kusakanikirana, onetsetsani kuti mwalumikiza molunjika kuti muchepetse kulumikizana. Dera la digito, dera la analogi, ndi dera lotulutsa phokoso pa bolodi la dera liyenera kupatulidwa, ndipo dera lovuta liyenera kuyendetsedwa kaye, ndipo njira yolumikizirana pakati pa mabwalo iyenera kuthetsedwa. Makamaka, ganizirani za wotchi, kukonzanso ndi kusokoneza mizere, musafanane ndi mizere iyi ndi mizere yosinthira yomwe ilipo, yomwe imawonongeka mosavuta ndi maginito olumikizana ndi ma electromagnetic coupling, zomwe zimapangitsa kukonzanso kapena kusokoneza mosayembekezereka. The overall layout should follow the following principles:

1. Magawo ogawira magwiridwe antchito, dera la analog ndi dera la digito pa PCB ayenera kukhala ndi mawonekedwe osiyanasiyana.

2. Malinga ndi ndondomeko ya chizindikiro cha dera kuti akonze mayunitsi ogwira ntchito, kuti chizindikirocho chikhalebe chofanana.

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. Zigawo zosokonezeka mosavuta siziyenera kuyandikana kwambiri, zolowetsa ndi zotulutsa ziyenera kukhala kutali.

How to design the signal of integrity PCB

Kupanga zingwe za PCB

Mizere yonse yama siginecha iyenera kusankhidwa pamaso pa ma waya a 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. Zingwe zama siginecha pamagawo osiyanasiyana ziyenera kuyendetsedwa molunjika kwa wina ndi mnzake kuti muchepetse kuphatikizika. Kukonzekera kwa mizere yazizindikiro kumakonzedwa bwino molingana ndi kayendetsedwe ka kayendedwe ka chizindikiro. Mzere wa siginecha wotuluka wadera suyenera kubwereranso kudera la mzere wa siginecha. High-speed signal lines should be kept as short as possible to avoid interfering with other signal lines. Pagawo lawiri, ngati kuli kofunikira, waya wadzipatula atha kuwonjezeredwa mbali zonse ziwiri za mzere wothamanga kwambiri. Mizere yonse yothamanga kwambiri pa bolodi la multilayer iyenera kutetezedwa molingana ndi kutalika kwa mizere ya wotchi.

Mfundo zazikuluzikulu za wiring ndi:

1. Momwe mungathere kusankha mawaya otsika kachulukidwe mawaya, ndi mawaya a siginecha momwe mungathere makulidwe ake osasinthasintha, othandizira kufananitsa kwa impedance. Kwa rf circuit, mapangidwe osamveka a mzere wa mzere wa chizindikiro, m’lifupi ndi kutalika kwa mizere angayambitse kusokoneza pakati pa mizere yotumizira chizindikiro.

2. Momwe mungathere kuti mupewe mawaya oyandikana nawo ndi mawaya otulutsa ndi mawaya ofananira mtunda wautali. Kuti muchepetse kuphatikizika kwa mizere yofananira, kusiyana pakati pa mizere yolumikizira kumatha kuonjezedwa, kapena malamba odzipatula amatha kuyikidwa pakati pa mizere yazizindikiro.

3. Kutalika kwa mzere pa PCB kudzakhala kofanana ndipo palibe kusintha kwa mzere m’lifupi komwe kudzachitike. PCB mawaya mapindikidwe sayenera kugwiritsa ntchito madigiri 90 ngodya, ayenera kugwiritsa ntchito arc kapena 135 madigiri ngodya, mmene ndingathere kusunga kupitiriza kwa mzere impedance.

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. Momwe mungathere kuchepetsa kutalika kwa waya, kuonjezera m’lifupi mwa waya, kumathandiza kuchepetsa kutsekeka kwa waya.

6. Pazidziwitso zowongolera ma switch, kuchuluka kwa waya wa SIGNAL PCB omwe amasintha dziko nthawi yomweyo ayenera kuchepetsedwa momwe angathere.