Ka moralo oa PCB boto, ka keketseho e potlakileng ea maqhubu, ho tla ba le tšitiso e ngata e fapaneng le ea boto ea PCB ea maqhubu a tlase. Ho feta moo, ka keketseho ea maqhubu le ho ikhanyetsa lipakeng tsa miniaturization le theko e tlase ea boto ea PCB, tšitiso ena e tla thatafala le ho feta.

Phuputsong ea ‘nete, re ka fihlela qeto ea hore ho na le likarolo tse’ ne tsa tšitiso, ho kenyelletsa lerata la phepelo ea motlakase, tšitiso ea mohala oa phetisetso, ho kopanya le tšitiso ea motlakase (EMI). Ka ho sekaseka mathata a fapaneng a tšitiso ea PCB e nang le maqhubu a phahameng le ho kopanya le boits’oaro mosebetsing, tharollo e sebetsang e ea pele.

Taba ea mantlha, lerata la phepelo ea motlakase

Ka potoloho e phahameng ea maqhubu, lerata la phepelo ea motlakase le na le tšusumetso e totobetseng ho lets’oao le phahameng la maqhubu. Ka hona, tlhoko ea pele ea phepelo ea motlakase ke lerata le tlase. Mekato e hloekileng e bohlokoa joaloka motlakase o hloekileng. Hobane’ng? Litšobotsi tsa matla li bonts’itsoe ho Setšoantšo sa 1. Ho hlakile hore phepelo ea motlakase e na le tšitiso e itseng, ‘me impedance e ajoa holim’a phepelo eohle ea motlakase, ka hona, lerata le tla eketsoa phepelong ea motlakase.

Then we should minimize the impedance of the power supply, so it is best to have a dedicated power supply layer and grounding layer. Moralo oa potoloho oa hf, ho molemo haholo ho rala phepelo ea motlakase e le lera ho fapana le bese ka makhetlo a mangata, hore lupu e tle e tsebe ho latela tsela ea tšitiso e nyane.

Ntle le moo, boto ea motlakase e tlameha ho fana ka lupu ea lets’oao bakeng sa matšoao ohle a hlahisitsoeng le a amoheloang ho PCB. Sena se fokotsa leqhubu la lets’oao mme ka hona e fokotsa lerata, leo hangata le hlokomolohuoang ke baqapi ba potoloho ea maqhubu a tlase.

Moralo o phahameng oa maqhubu a PCB o hlaha ka tharollo ea tšitiso

Setšoantšo sa 1: Litšobotsi tsa matla

Ho na le mekhoa e mengata ea ho felisa lerata la motlakase ho moralo oa PCB:

1. Hlokomela lesoba le palameng boto: lesoba le phunyang le hloka likheo tse momahaneng holim’a phepelo ea motlakase ho siea sebaka hore lesoba le fete. Haeba ho buloa ha lera la phepelo ea motlakase ho le leholo haholo, ho tlameha ho ama leqhubu la lets’oao, lets’oao le qobelloa ho feta, sebaka sa lupu se eketseha, le lerata lea eketseha. Ka nako e ts’oanang, haeba mela e mengata ea lipontšo e kopantsoe haufi le monyako ‘me e arolelana sekoahelo se le seng, impedance e tloaelehileng e tla baka crosstalk. Sheba setšoantšo sa 2.

Moralo o phahameng oa maqhubu a PCB o hlaha ka tharollo ea tšitiso

Setšoantšo sa 2: Tsela e tloaelehileng ea ho feta ha lets’oao la lets’oao

2. Mohala oa khokahano o hloka mobu o lekaneng: lets’oao le leng le le leng le hloka ho ba le leqhubu la lona la sets’oants’o, ‘me sebaka sa lupu sa lets’oao le lupu se nyane kamoo ho ka khonehang, ke ho re, lets’oao le lupu li lokela ho tšoana.

3. Phepelo ea matla a analoge le a dijithale ho arohana: lisebelisoa tse nang le maqhubu a phahameng ka kakaretso li bobebe haholo leratong la dijithale, ka hona tse peli li lokela ho aroloa, li hokahane hammoho monyako oa phepelo ea motlakase, haeba lets’oao ho likarolo tsa analog le tsa dijithale tsa mantsoe, a ka beoa ka har’a lets’oao ho fokotsa sekoti. Nako ea dijithale-analog e sebelisitsoeng bakeng sa lupu ea lets’oao e bonts’oa ho Setšoantšo sa 3.

Moralo o phahameng oa maqhubu a PCB o hlaha ka tharollo ea tšitiso

Setšoantšo sa 3: Lijana tsa dijithale – analog bakeng sa lupu ea lets’oao

4. Qoba ho kopana hoa phepelo ea motlakase e arohaneng lipakeng tsa mekhahlelo: ho seng joalo lerata la potoloho le ka feta habonolo ka har’a coupling ea parasitic capacitive.

5. Khetholla likarolo tse hlokolosi: joalo ka PLL.

6. Beha thapo ea motlakase: Ho fokotsa lupu ea lets’oao, beha thapo ea motlakase moeling oa mola oa lets’oao ho fokotsa lerata, joalo ka ha ho bonts’itsoe ho Setšoantšo sa 4.

Moralo o phahameng oa maqhubu a PCB o hlaha ka tharollo ea tšitiso

Setšoantšo sa 4: Beha thapo ea motlakase pela mohala oa lets’oao

Two, transmission line

Ho na le mela e ‘meli feela ea phetisetso ho PCB:

Bothata bo boholohali ba mola oa lente le mola oa microwave ke ponahatso. Ho nahanisisa ho tla baka mathata a mangata. Mohlala, lets’oao la mojaro e tla ba superposition ea lets’oao la pele le lets’oao la echo, le tla eketsa bothata ba tlhahlobo ea matšoao. Ponahatso e baka tahlehelo ea ho khutla (tahlehelo ea ho khutla), e amang lets’oao hampe joalo ka tšitiso ea lerata la tlatsetso:

1. Letšoao le bonts’itsoeng mohloling oa lets’oao le tla eketsa lerata la sistimi, ho etsa hore ho be thata haholo ho moamoheli ho khetholla lerata ho lets’oao;

2. Letšoao lefe kapa lefe le bonts’itsoeng le tla nyenyefatsa boleng ba lets’oao mme le fetole sebopeho sa lets’oao la ho kenya. Generally speaking, the solution is mainly impedance matching (for example, the impedance of the interconnection should very match the impedance of the system), but sometimes the calculation of impedance is more troublesome, you can refer to some transmission line impedance calculation software. The methods of eliminating transmission line interference in PCB design are as follows:

(a) Qoba ho emisoa ha mehala ea phetisetso. Ntlha ea ho emisa ho emisa ke ntlha ea phetoho ea mohala oa phetisetso, joalo ka sekhutlo se otlolohileng, ka lesoba, jj., E lokela ho qojoa kamoo ho ka khonehang. Mekhoa: Ho qoba likhutlo tse otlolohileng tsa mohala, ho fihla moo ho ka khonehang ho ea ho 45 ° Angle kapa arc, Angle e kholo le eona e ka ba; Sebelisa tse seng kae ka masoba kamoo ho ka khonehang, hobane e ‘ngoe le e’ ngoe ka lesoba ke ho emisa ha impedance, joalo ka ha ho bonts’itsoe ho FIG. 5; Signals from the outer layer avoid passing through the inner layer and vice versa.

Moralo o phahameng oa maqhubu a PCB o hlaha ka tharollo ea tšitiso

Figure 5: Method for eliminating transmission line interference

(b) Se ke oa sebelisa methati ea lithupa. Hobane mohala ofe kapa ofe oa qubu ke mohloli oa lerata. Haeba mohala oa qubu o le mokhutšoane, o ka hokeloa qetellong ea mohala oa phetisetso; Haeba mohala oa qubu o le telele, o tla nka mohala o moholo oa phetisetso e le mohloli mme o hlahise ponaletso e ntle, e tla thatafatsa bothata. Ho kgothaletswa hore o se ke oa e sebelisa.

Ea boraro, ho kopanya

1. Kopano e tloaelehileng ea impedance: ke mocha o tloaelehileng oa ho kopanya, ke hore, mohloli oa tšitiso le sesebelisoa se sitisitsoeng hangata se arolelana batsamaisi ba bang (joalo ka phepelo ea motlakase, bese, le motheo o tloaelehileng), joalo ka ha ho bonts’itsoe ho Setšoantšo sa 6.

Moralo o phahameng oa maqhubu a PCB o hlaha ka tharollo ea tšitiso

Setšoantšo sa 6: Coupling e tloaelehileng ea impedance

Le kanaleng lena, ho khutla ha Ic ho baka motlakase o tloaelehileng oa mofuta ona letotong la hajoale, o amang seamohedi.

2. The field common-mode coupling will cause the radiation source to cause common-mode voltages in the loop formed by the interfered circuit and on the common reference surface.

Haeba matla a khoheli a le teng, boleng ba motlakase o tloaelehileng o hlahisoang ke potoloho ea lefatše ke Vcm = – (△ B / △ t) * sebaka (moo △ B = phetoho ea matla a khoheli a khoheli). Haeba e le tšimo ea motlakase, ha boleng ba eona ba motlakase bo tsejoa, matla a eona a susumetsoang ke motlakase: Vcm = (L * H * F * E) / 48, foromo e loketse L (m) = 150MHz, ho feta moeli ona, lipalo tsa matla a phahameng a hlohlellelitsoeng li ka nolofatsoa joalo ka: Vcm = 2 * H * E.

3. Ho kopanya masimo a fapaneng ka mokhoa o fapaneng: ho bolela mahlaseli a tobileng ka para ea terata kapa boto ea potoloho moetapele le ho kenella ha eona ha loop. If you get as close to the two wires as possible. Khokahano ena e fokotsehile haholo, kahoo lithapo tse peli li ka sotheha hammoho ho fokotsa tšitiso.

4. Inter-line coupling (crosstalk) can cause unwanted coupling between any line or parallel circuit, which will greatly damage the performance of the system. Mofuta oa eona o ka aroloa ka “crosstalk” ea capacitive le crosstalk ea kutlo.

Ea pele ke hobane matla a likokoana-hloko pakeng tsa mela a etsa lerata mohloling oa lerata hammoho le mohala o amohelang lerata ka ente ea hajoale. Ea morao-rao e ka nahanoa e le ho kopanya lipontšo lipakeng tsa mekhahlelo ea mantlha ea phetoho ea likokoana-hloko e sa batleheng. Boholo ba crosstalk e kenyang maikutlo bo ipapisitse le ho ba haufi le likonopo tse peli, boholo ba sebaka sa lupu, le khatello ea mojaro o amehileng.

5. Ho hokahanya thapo ea motlakase: Likhoele tsa motlakase tsa ac kapa tsa DC li sitisoa ke tšitiso ea motlakase

Fetisetsa lisebelisoa tse ling.

Ho na le mekhoa e mengata ea ho felisa crosstalk ho moralo oa PCB:

1. Mefuta ka bobeli ea crosstalk e ea eketseha ka keketseho ea “impedance” ea mojaro, ka hona, mela ea lets’oao e mamellang ho kena-kenana le sesosa sa crosstalk e lokela ho emisoa ka nepo.

2. Nolofatsa sebaka se pakeng tsa mela ea lets’oao ho fokotsa ka katleho crosstalk ea capacitive. Tsamaiso ea fatše, karohano lipakeng tsa wiring (joalo ka mela e sebetsang ea lets’oao le mela ea mobu bakeng sa ho itšehla thajana, haholoholo maemong a ho qhomela lipakeng tsa mola oa lets’oao le mobu ho ea ho sekhahla) le ho fokotsa ho kenella ha lead.

3. Capacitive crosstalk le eona e ka fokotsoa ka nepo ka ho kenya terata ea mobu lipakeng tsa mela ea matšoao e haufi, e tlamehang ho hokahanngoa le sebopeho selemo se seng le se seng sa bokahohle.

4. Bakeng sa crosstalk e nang le kelello, sebaka sa lupu se lokela ho fokotsoa, ​​’me haeba se lumelloa, lupu e lokela ho tlosoa.

5. Qoba likonopo tsa ho arolelana lipontšo.

6. Ela hloko bots’epehi ba lets’oao: moqapi o lokela ho kenya tšebetsong liphetho tsa ts’ebetso ea tjheseletsa ho rarolla bots’epehi ba lets’oao. Baqapi ba sebelisang mokhoa ona ba ka shebana le bolelele ba microstrip ea tšireletso ea koporo e sirelletsang molemong oa ho fumana ts’ebetso e ntle ea bots’epehi. Bakeng sa lits’ebetso tse nang le likhokelo tse teteaneng moahong oa puisano, moqapi a ka sebelisa PCB joalo ka sesebelisoa.

Bone, tšitiso ea motlakase

As the speed increases, EMI becomes more and more serious and presents in many aspects (such as electromagnetic interference at interconnects). High-speed devices are particularly sensitive to this and will receive high-speed spurious signals, while low-speed devices will ignore such spurious signals.

Ho na le mekhoa e mengata ea ho felisa tšitiso ea motlakase ho moralo oa PCB:

1. Fokotsa likonopo: Lupu ka leng le lekana le lenakana, ka hona re hloka ho fokotsa palo ea likonopo, sebaka sa likonopo le matla a lenakana a likonopo. Make sure the signal has only one loop path at any two points, avoid artificial loops and use the power layer whenever possible.

2. Ho sefa: Ho sefa ho ka sebelisoa ho fokotsa EMI moleng oa motlakase le moleng oa lets’oao. Ho na le mekhoa e meraro: decoupling capacitor, EMI filter le magnetic element. Sefe ea EMI e bonts’oa ho Setšoantšo sa 7.

Moralo o phahameng oa maqhubu a PCB o hlaha ka tharollo ea tšitiso

Setšoantšo sa 7: Mefuta ea ho sefa

3. Tshireletso. Ka lebaka la bolelele ba taba hammoho le lingoloa tse ngata tse sirelletsang lipuisano, ha e sa le selelekela se ikhethang.

4. Fokotsa lebelo la lisebelisoa tsa maqhubu a phahameng.

5. Eketsa khaello ea dielectric ea board ea PCB, e ka thibelang likarolo tse phahameng tsa maqhubu joalo ka mola oa phetisetso haufi le boto hore e se ke ea chaba kantle; Eketsa botenya ba boto ea PCB, fokotsa botenya ba mola oa microstrip, e ka thibela motlakase oa motlakase oa spillover, hape e ka thibela mahlaseli.

Mothating ona, re ka fihlela qeto ea hore ka moralo oa hf PCB, re lokela ho latela melao-motheo e latelang:

1. Kopano le botsitso ba phepelo ea motlakase le mobu.

2. Ho nahanoa ka hloko ka wiring le ho emisoa ka nepo ho ka felisa maikutlo.

3. Ho nahanoa ka hloko ka wiring le ho emisa ka nepo ho ka fokotsa crosstalk e matlafatsang.

4. Ho hatella lerata hoa hlokahala ho fihlela litlhoko tsa EMC.