Mukugadzirwa kwe Pcb bhodhi, nekuwedzera nekukurumidza kwekuwanda, pachave nekukanganisa kwakawanda kwakasiyana neiyo yakaderera-frequency PCB bhodhi. Zvakare, nekuwedzera kwehuwandu uye kupesana pakati peye miniaturization uye yakaderera mutengo wepcb board, izvi zvinokanganisa zvichave zvakanyanya kuomarara.

Mukutsvagurudza chaiko, tinogona kugumisa kuti pane zvinhu zvina zvinokanganisa, zvinosanganisira ruzha rwemagetsi, kupindirana kwetambo kupindirana, kubatanidza uye kukanganisa kwemagetsi (EMI). Kubudikidza nekuongorora matambudziko akasiyana ekukanganisa eiyo yepamusoro-frequency PCB uye kusanganisa nekuita basa, mhinduro dzinobudirira dzinoiswa kumberi.

Kutanga, ruzha rwemagetsi

Mune yakakura frequency frequency, ruzha rwemagetsi rune simba riri pachena pane yakakwira frequency chiratidzo. Therefore, the first requirement of the power supply is low noise. Pasi rakachena rakakosha semagetsi akachena. Sei? Hunhu hwemagetsi hunoratidzwa muMufananidzo 1. Zviripachena, magetsi anemwe impedance, uye iyo impedance inogoverwa pamusoro pesimba rese remagetsi, saka, ruzha ruchawedzerwa kune magetsi.

Then we should minimize the impedance of the power supply, so it is best to have a dedicated power supply layer and grounding layer. Mune hf dhizaini dhizaini, zvirinani kugadzira dhizaini seyadhi kupfuura bhazi mune dzakawanda zviitiko, kuitira kuti chiuno chigare chichitevedza nzira yekushomeka kwemhedzisiro.

Uye zvakare, iro bhodhi remagetsi rinofanirwa kupa chiuno chechiratidzo kune ese akagadzirwa uye akagashira masaini paPCB. Izvi zvinoderedza chiratidzo chejira uye nekudaro inoderedza ruzha, iyo inowanzo kufuratirwa nevashoma-frequency wedunhu vagadziri.

Yakakwira-frequency PCB dhizaini inoitika yekukanganisa mhinduro

Mufananidzo 1: Simba maitiro

Pane nzira dzinoverengeka dzekubvisa ruzha rwemagetsi muPCB dhizaini:

1. Note the through hole on the board: the through hole requires etched openings on the power supply layer to leave space for the through hole to pass through. Kana kuvhurwa kwesimba rekugovera magetsi kwakanyanyisa kukura, inosungirwa kukanganisa chiuno chechiratidzo, chiratidzo chinomanikidzwa kupfuura, nzvimbo yekurembera inowedzera, uye ruzha rwunowedzera. At the same time, if several signal lines are clustered near the opening and share the same loop, the common impedance will cause crosstalk. Ona Mufananidzo 2.

Yakakwira-frequency PCB dhizaini inoitika yekukanganisa mhinduro

Mufananidzo 2: Yakajairika nzira yekupfuura chiratidzo chiuno

2. The connection line needs enough ground: each signal needs to have its own proprietary signal loop, and the loop area of the signal and loop is as small as possible, that is to say, the signal and loop should be parallel.

3. Analog uye dhijitari magetsi ekuti apatsanure: ma-frequency-frequency madhiragi anowanzo kuve anonzwika kudhijitari ruzha, saka iwo maviri anofanira kupatsanurwa, akabatana pamwechete pamusuwo wesimba remagetsi, kana chiratidzo chakanangana neanalogog uye nedhijitari zvikamu zve mazwi, anogona kuiswa mucherechedzo kuyambuka chiuno kuti udzikise nzvimbo yechiuno. Iyo yedhijitari-analogi span inoshandiswa kune chiratidzo chiuno inoratidzwa muMufananidzo 3.

Yakakwira-frequency PCB dhizaini inoitika yekukanganisa mhinduro

Figure 3: Digital – analog span for signal loop

4. Avoid overlapping of separate power supplies between layers: otherwise circuit noise can easily pass through parasitic capacitive coupling.

5. Isolate sensitive components: such as PLL.

6. Place the power cable: To reduce the signal loop, place the power cable on the edge of the signal line to reduce the noise, as shown in Figure 4.

Yakakwira-frequency PCB dhizaini inoitika yekukanganisa mhinduro

Mufananidzo 4: Isa tambo yemagetsi padivi pemutsara wechiratidzo

Two, transmission line

Pane mitsara miviri chete yekutapurirana muPCB:

Dambudziko hombe rerabhoni mutsetse uye microwave mutsetse kuratidza. Kufungisisa kunokonzera matambudziko mazhinji. Semuenzaniso, chiratidzo chemutoro chichava chinzvimbo chechiratidzo chekutanga uye chiratidzo cheecho, icho chinowedzera kuoma kwekuwongorora chiratidzo. Kufungisisa kunokonzeresa kudzoka kurasikirwa (kudzoka kurasikirwa), izvo zvinokanganisa chiratidzo zvakanyanya sekuwedzera kwekukanganisa ruzha:

1. Chiratidzo chakaratidzirwa kumashure kunobva chiratidzo kunowedzera ruzha rwechirongwa, zvichiita kuti zviome kune anogamuchira kusiyanisa ruzha kubva kuchiratidzo;

2. Any reflected signal will basically degrade the signal quality and change the shape of the input signal. 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) Dzivisa impedance discontinuity yemitambo yekufambisa. Iyo poindi yekumisikidza impedance ndiyo poindi yekufambisa mutsara shanduko, senge yakatwasuka kona, kuburikidza neburi, nezvimwe, inofanirwa kudzivirirwa kusvika pazvinogoneka. Maitiro: Kudzivirira makona akatwasuka emutsara, kusvika pazvinogona kuenda 45 ° Angle kana arc, hombe Angle inogona zvakare kuve; Shandisa vashoma kuburikidza nemakomba sezvinobvira, nekuti imwe neimwe kuburikidza negomba ndeye impedance discontinuity, sezvakaratidzwa muFIG. 5; Signals from the outer layer avoid passing through the inner layer and vice versa.

Yakakwira-frequency PCB dhizaini inoitika yekukanganisa mhinduro

Figure 5: Method for eliminating transmission line interference

(b) Do not use stake lines. Nekuti chero mutsetse wedutu ndiwo manyuko eruzha. Kana mutsetse wedutu wakapfupika, unogona kusunganidzwa panoperera tambo yekufambisa; Kana mutsetse wedutu wakareba, zvinotora main tambo yekufambisa sosi uye kuburitsa kuratidzwa kukuru, kunozoomesesa dambudziko. Inokurudzirwa kuti usashandise.

Yetatu, kubatanidza

1. Common impedance coupling: it is a common coupling channel, that is, the interference source and the interfered device often share some conductors (such as loop power supply, bus, and common grounding), as shown in Figure 6.

Yakakwira-frequency PCB dhizaini inoitika yekukanganisa mhinduro

Mufananidzo 6: Zvakajairika impedance kubatanidza

In this channel, the drop back of the Ic causes a common-mode voltage in the series current loop, affecting the receiver.

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.

If the magnetic field is dominant, the value of the common-mode voltage generated in the series ground circuit is Vcm=-(△B/△t)* area (where △B= change in magnetic induction intensity). If it is an electromagnetic field, when its electric field value is known, its induced voltage: Vcm=(L* H *F*E)/48, the formula is suitable for L(m)=150MHz, beyond this limit, the calculation of the maximum induced voltage can be simplified as: Vcm=2* H *E.

3. Differential mode field coupling: refers to the direct radiation by wire pair or circuit board on the lead and its loop induction received. If you get as close to the two wires as possible. Kubatanidza uku kwakadzikira kwazvo, saka waya mbiri dzinogona kumonyaniswa pamwechete kudzikisira kupindirana.

4. Inter-line coupling (crosstalk) can cause unwanted coupling between any line or parallel circuit, which will greatly damage the performance of the system. Its type can be divided into capacitive crosstalk and perceptual crosstalk.

The former is because the parasitic capacitance between the lines makes the noise on the noise source coupled to the noise receiving line through current injection. The latter can be thought of as the coupling of signals between the primary stages of an unwanted parasitic transformer. Iko kukura kweiyo inductive crosstalk kunoenderana nekuswedera kwemaviri malupu, saizi yenzvimbo yechiuno, uye impedance yemutoro wakabatwa.

5. Simba tambo yekubatanidza: Iyo ac kana DC tambo dzemagetsi dzinovhiringidzwa nemagetsi emagetsi

Chinjana kune zvimwe zvishandiso.

There are several ways to eliminate crosstalk in PCB design:

1. Ose maviri marudzi ecrosstalk anowedzera pamwe nekuwedzera kwemutoro impedance, saka mitsara yemasaini inokanganisa kupindirana kunokonzerwa necrosstalk inofanira kumiswa nenzira kwayo.

2. Kwidziridza chinhambwe pakati pemitsetse yemasaini kuti unyatso deredza capacitive crosstalk. Ground manejimendi, kupatsanurana pakati pewiring (senge inoshandira mitsara yemasaini uye mitsara yepasi yekuzviparadzanisa, kunyanya mudanho rekusvetuka pakati peyechiratidzo mutsetse nepasi kusvika padanho) uye kudzora kutungamira inductance.

3. Capacitive crosstalk can also be effectively reduced by inserting a ground wire between adjacent signal lines, which must be connected to the formation every quarter of a wavelength.

4. Kune crosstalk inonzwisisika, nzvimbo yekutenderera inofanirwa kudzikiswa, uye kana ichibvumidzwa, chiuno chinofanira kubviswa.

5. Avoid signal sharing loops.

6. Teerera kutendeseka kwechiratidzo: mugadziri anofanirwa kuita zvinopera mukugadzirisa nzira yekugadzirisa chiratidzo chekuvimbika. Vagadziri vanoshandisa nzira iyi vanogona kutarisisa paiyo microstrip kureba kweye inodzivirira mhangura foil kuitira kuti vawane kuita kwakanaka kwekutendeka kwechiratidzo. For systems with dense connectors in the communication structure, the designer can use a PCB as the terminal.

Four, electromagnetic interference

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.

Pane nzira dzinoverengeka dzekubvisa kupesana nemagetsi muPCB dhizaini:

1. Deredza zvishwe: Chiuno chega chega chakaenzana neiyo kanyanga, saka tinofanirwa kudzikisa huwandu hwezvishongo, nzvimbo yezvishongo uye mhedzisiro yehutachiona hwezvishongo. Make sure the signal has only one loop path at any two points, avoid artificial loops and use the power layer whenever possible.

2. Filtering: Filtering can be used to reduce EMI on both the power line and the signal line. There are three methods: decoupling capacitor, EMI filter and magnetic element. EMI filter is shown in Figure 7.

Yakakwira-frequency PCB dhizaini inoitika yekukanganisa mhinduro

Mufananidzo 7: Filter mhando

3. The shielding. Nekuda kwehurefu hwenyaya iyi pamwe nekuwanda kwenhaurirano inodzivirira zvinyorwa, hapasisina sumo chaiyo.

4. Reduce the speed of high-frequency devices.

5. Wedzera dielectric inogara iripo pcb board, iyo inogona kudzivirira iyo yakakwira frequency zvikamu senge yekufambisa mutsara padyo nebhodhi kubva kubuda kunze; Increase the thickness of PCB board, minimize the thickness of microstrip line, can prevent electromagnetic line spillover, can also prevent radiation.

At this point, we can conclude that in hf PCB design, we should follow the following principles:

1. Unification and stability of power supply and ground.

2. Kunyatsotariswa wiring uye kumisikidzwa kwakakodzera kunogona kubvisa kufunga.

3. Kunyatsotariswa wiring uye chaiyo kumiswa kunogona kudzora capacitive uye inductive crosstalk.

4. Ruzha kudzvinyirira hunodiwa kuzadzikisa EMC zvinodiwa.