With the development of communication technology, handheld radio igbimọ igbohunsafẹfẹ giga-igbohunsafẹfẹ imọ -ẹrọ jẹ lilo siwaju ati siwaju sii ni lilo, gẹgẹbi: pager alailowaya, foonu alagbeka, PDA alailowaya, ati bẹbẹ lọ, iṣẹ ti agbegbe igbohunsafẹfẹ redio taara ni ipa lori didara gbogbo ọja. Ọkan ninu awọn abuda ti o tobi julọ ti awọn ọja amusowo wọnyi jẹ miniaturization, ati miniaturization tumọ si pe iwuwo awọn paati ga pupọ, eyiti o jẹ ki awọn paati (pẹlu SMD, SMC, barerún igboro, ati bẹbẹ lọ) dabaru pẹlu ara wọn ni olokiki pupọ. Ti o ba jẹ pe ami kikọlu kikọlu itanna ko ni itọju daradara, gbogbo eto Circuit le ma ṣiṣẹ daradara. Nitorinaa, bii o ṣe le ṣe idiwọ ati dinku kikọlu itanna ati imudara ibamu ibaramu ti di koko pataki ni apẹrẹ ti PCB Circuit RF. Circuit kanna, oriṣiriṣi apẹrẹ apẹrẹ PCB, atọka iṣẹ rẹ yoo yatọ pupọ. Iwe yii jiroro bi o ṣe le mu iṣẹ ṣiṣe ti Circuit pọ si lati ṣaṣeyọri awọn ibeere ibamu itanna nigba lilo Protel99 SE sọfitiwia lati ṣe apẹrẹ PCB Circuit rf ti awọn ọja ọpẹ.

1. Asayan ti awo

The substrate of printed circuit board includes organic and inorganic categories. Awọn ohun -ini pataki julọ ti sobusitireti jẹ igbagbogbo aisi -itanna ε R, ifosiwewe itusilẹ (tabi pipadanu aisi -itanna) Tan δ, isodipupo imugboroosi gbona CET ati gbigba ọrinrin. ε R affects circuit impedance and signal transmission rate. Fun awọn iyika igbohunsafẹfẹ giga, ifarada iyọọda jẹ akọkọ ati ifosiwewe pataki diẹ sii lati gbero, ati sobusitireti pẹlu ifarada iyọọda kekere yẹ ki o yan.

2. PCB design process

Because Protel99 SE software is different from Protel 98 and other software, the process of PCB design by Protel99 SE software is briefly discussed.

① Because Protel99 SE adopts the PROJECT database mode management, which is implicit in Windows 99, so we should first set up a database file to manage the circuit schematic diagram and PCB layout designed.

② Design of schematic diagram. Lati le mọ asopọ nẹtiwọọki, gbogbo awọn paati ti a lo gbọdọ wa ninu ile -ikawe paati ṣaaju apẹrẹ ipilẹ; bibẹẹkọ, awọn paati ti o nilo yẹ ki o ṣe ni SCHLIB ati fipamọ sinu faili ile -ikawe naa. Lẹhinna, o kan pe awọn paati ti a beere lati ibi ikawe paati ki o so wọn pọ ni ibamu si aworan apẹrẹ Circuit ti a ṣe apẹrẹ.

③ After the schematic design is completed, a network table can be formed for use in PCB design.

④PCB design. A. Apẹrẹ CB ati ipinnu iwọn. The shape and size of PCB are determined according to the position of PCB in the product, the size and shape of the space and the cooperation with other parts. Draw the shape of the PCB using the PLACE TRACK command on MECHANICAL LAYER. B. Ṣe awọn iho ipo, awọn oju ati awọn aaye itọkasi lori PCB ni ibamu si awọn ibeere SMT. C. Production of components. If you need to use some special components that do not exist in the component library, you need to make components before layout. Ilana ṣiṣe awọn paati ni Protel99 SE jẹ irọrun ti o rọrun. Yan pipaṣẹ “ṢE ṢEṢE LIBRARY” ni mẹnu “DESIGN” lati tẹ window ṣiṣe ṣiṣe COMPONENT, lẹhinna yan “aṣẹ TUNTUN” ninu akojọ “ỌRỌ” si awọn paati apẹrẹ. Ni akoko yii, kan fa PAD ti o baamu ni ipo kan ki o satunkọ rẹ sinu PAD ti o nilo (pẹlu apẹrẹ, iwọn, iwọn ila opin ati Angle ti PAD, ati bẹbẹ lọ, ati samisi orukọ PIN ti o baamu ti PAD) ni TOP LAYER pẹlu aṣẹ ti PLACE PAD ati bẹbẹ lọ ni ibamu si apẹrẹ ati iwọn ti paati gangan. Then use the PLACE TRACK command to draw the maximum appearance of the component in the TOP OVERLAYER, select a component name and store it in the component library. D. Lẹhin ti a ti ṣe awọn paati, ipilẹṣẹ ati wiwakọ yoo ṣee ṣe. Awọn apakan meji wọnyi ni yoo jiroro ni awọn alaye ni isalẹ. E. Check after the above procedure is complete. Ni ọna kan, eyi pẹlu ayewo ti opo Circuit, ni apa keji, o jẹ dandan lati ṣayẹwo ibaramu ati apejọ ti ara wọn. The circuit principle can be checked manually or automatically by network (the network formed by schematic diagram can be compared with the network formed by PCB). F. Lẹhin ṣiṣe ayẹwo, pamosi ati gbejade faili naa. Ni Protel99 SE, o gbọdọ ṣiṣẹ aṣẹ ikọja ni aṣayan FILE lati ṣafipamọ FILE si ọna ti a sọtọ ati FILE (pipaṣẹ IMPORT ni lati gbe FILE wọle si Protel99 SE). Akiyesi: Ninu aṣayan Protel99 SE “FILE” “Fipamọ ẸDI BI…” ” Lẹhin pipaṣẹ naa, orukọ faili ti o yan ko han ni Windows 98, nitorinaa faili ko le rii ni Oluṣakoso Oro. Eyi yatọ si “Fipamọ Bi…” ni Protel 98. Ko ṣiṣẹ gangan kanna.

3. Components layout

Nitori SMT gbogbogbo nlo igbona ooru ileru infurarẹẹdi si alurinmorin si awọn paati alurinmorin, ipilẹ awọn paati yoo ni ipa lori didara awọn isẹpo solder, lẹhinna ni ipa lori ikore awọn ọja. For PCB design of rf circuit, electromagnetic compatibility requires that each circuit module does not generate electromagnetic radiation as far as possible, and has a certain ability to resist electromagnetic interference. Therefore, the layout of components also directly affects the interference and anti-interference ability of the circuit itself, which is also directly related to the performance of the designed circuit. Therefore, in the design of RF circuit PCB, in addition to the layout of ordinary PCB design, we should also consider how to reduce the interference between various parts of the RF circuit, how to reduce the interference of the circuit itself to other circuits and the anti-interference ability of the circuit itself. Gẹgẹbi iriri, ipa ti Circuit rf gbarale kii ṣe lori atọka iṣẹ ti igbimọ Circuit RF funrararẹ, ṣugbọn tun lori ibaraenisepo pẹlu igbimọ processing Sipiyu si iwọn nla. Nitorinaa, ni apẹrẹ PCB, ipilẹ ti o peye jẹ pataki pataki.

General layout principle: components should be arranged in the same direction as far as possible, and the bad welding phenomenon can be reduced or even avoided by selecting the direction of PCB entering the tin melt system; Gẹgẹbi iriri, aaye laarin awọn paati yẹ ki o wa ni o kere ju 0.5mm lati pade awọn ibeere ti awọn paati fifa tin. Ti aaye ti igbimọ PCB gba laaye, aaye laarin awọn paati yẹ ki o gbooro bi o ti ṣee. Fun awọn panẹli ilọpo meji, ẹgbẹ kan yẹ ki o ṣe apẹrẹ fun SMD ati awọn paati SMC, ati ẹgbẹ keji jẹ awọn paati ọtọ.

Akiyesi ni apẹrẹ:

* First determine the position of interface components on the PCB with other PCB boards or systems, and pay attention to the coordination of interface components (such as the orientation of components, etc.).

* Nitori iwọn kekere ti awọn ọja amusowo, awọn paati ti wa ni idayatọ ni ọna iwapọ, nitorinaa fun awọn paati nla, a gbọdọ fun ni pataki lati pinnu ipo ti o yẹ, ati gbero iṣoro ti isọdọkan laarin ara wọn.

* eto onínọmbà itupalẹ ṣọra, sisẹ ohun idena Circuit (gẹgẹbi Circuit ampilifaya igbohunsafẹfẹ giga, idapọpọ Circuit ati Circulation demodulation, ati bẹbẹ lọ), bi o ti ṣee ṣe lati ya ifihan agbara lọwọlọwọ ti o wuwo ati ami alailagbara lọwọlọwọ, Circuit ifihan oni nọmba lọtọ ati ami afọwọṣe analog Circuit, pari iṣẹ kanna ti Circuit yẹ ki o ṣeto ni sakani kan, nitorinaa dinku agbegbe lupu ifihan; Nẹtiwọọki sisẹ ti apakan kọọkan ti Circuit gbọdọ wa ni asopọ nitosi, nitorinaa kii ṣe itankalẹ nikan le dinku, ṣugbọn tun iṣeeṣe kikọlu le dinku, ni ibamu si agbara kikọlu alatako ti Circuit naa.

* Awọn iyika sẹẹli ẹgbẹ ni ibamu si ifamọra wọn si ibaramu itanna ni lilo. The components of the circuit that are vulnerable to interference should also avoid interference sources (such as interference from the CPU on the data processing board).

4. Awọn gbigbe

After the components are laid out, wiring can begin. The basic principle of wiring is: under the condition of assembly density, low-density wiring design should be selected as far as possible, and signal wiring should be as thick and thin as possible, which is conducive to impedance matching.

Fun Circuit rf, apẹrẹ aironu ti itọsọna laini ifihan, iwọn ati aye laini le fa kikọlu laarin awọn laini ifihan ifihan ifihan; Ni afikun, ipese agbara eto funrararẹ tun wa kikọlu ariwo, nitorinaa ninu apẹrẹ ti PCB Circuit RF gbọdọ wa ni akiyesi ni kikun, wiwu ti o ni imọran.

Nigbati wiwakọ, gbogbo wiwa yẹ ki o jinna si aala ti igbimọ PCB (nipa 2mm), ki o ma ṣe fa tabi ni ewu ti o farapamọ ti fifọ okun waya lakoko iṣelọpọ ọkọ PCB. Laini agbara yẹ ki o jẹ jakejado bi o ti ṣee ṣe lati dinku resistance ti lupu. Ni akoko kanna, itọsọna ti laini agbara ati laini ilẹ yẹ ki o wa ni ibamu pẹlu itọsọna ti gbigbe data lati mu agbara ilodi si kikọlu. Awọn laini ifihan yẹ ki o kuru bi o ti ṣee ati pe nọmba awọn iho yẹ ki o dinku bi o ti ṣee. Kikuru asopọ laarin awọn paati, dara julọ, lati dinku pinpin awọn iwọn ati kikọlu itanna laarin ara wọn; For incompatible signal lines should be far away from each other, and try to avoid parallel lines, and in the positive two sides of the application of mutual vertical signal lines; Wiring in need of corner address should be 135° Angle as appropriate, avoid turning right angles.

Laini ti o sopọ taara pẹlu paadi ko yẹ ki o gbooro pupọ, ati laini yẹ ki o kuro ni awọn paati ti a ti ge asopọ bi o ti ṣee ṣe lati yago fun Circuit kukuru; Holes should not be drawn on components, and should be far away from disconnected components as far as possible to avoid virtual welding, continuous welding, short circuit and other phenomena in production.

In PCB design of rf circuit, the correct wiring of power line and ground wire is particularly important, and reasonable design is the most important means to overcome electromagnetic interference. Quite a lot of interference sources on PCB are generated by power supply and ground wire, among which ground wire causes the most noise interference.

Idi akọkọ ti okun waya ilẹ rọrun lati fa kikọlu itanna jẹ ifura ti okun waya ilẹ. When a current flows through the ground, a voltage will be generated on the ground, resulting in the ground loop current, forming the loop interference of the ground. When multiple circuits share a single piece of ground wire, common impedance coupling occurs, resulting in what is known as ground noise. Therefore, when wiring the ground wire of the RF circuit PCB, do:

* Ni akọkọ, Circuit ti pin si awọn ohun amorindun, Circuit rf ni a le pin ni ipilẹ si titobi igbohunsafẹfẹ giga, dapọ, idapọmọra, gbigbọn agbegbe ati awọn ẹya miiran, lati pese aaye itọkasi ti o pọju fun aaye Circuit module Circuit kọọkan, nitorinaa ifihan agbara le ti wa ni zqwq laarin o yatọ si Circuit modulu. Lẹhinna o ṣe akopọ ni aaye nibiti PCB Circuit RF ti sopọ si ilẹ, ie ṣe akopọ ni ilẹ akọkọ. Niwọn bi aaye itọkasi kan ṣoṣo wa, ko si idapọ ikọlu ikọlu ti o wọpọ ati nitorinaa ko si iṣoro kikọlu ara ẹni.

* Agbegbe oni -nọmba ati agbegbe analog bi o ti ṣee ṣe ipinya okun ilẹ ti o ṣeeṣe, ati ilẹ oni -nọmba ati ilẹ analog lati ya sọtọ, nikẹhin sopọ si ilẹ ipese agbara.

* Waya ilẹ ni apakan kọọkan ti Circuit yẹ ki o tun fiyesi si ipilẹ ipilẹ aaye kan, dinku agbegbe lupu ifihan, ati adirẹsi Circuit àlẹmọ ti o baamu nitosi.

* Ti aaye ba yọọda, o dara lati ya sọtọ modulu kọọkan pẹlu okun waya ilẹ lati ṣe idiwọ ipa ọna asopọ ifihan laarin ara wọn.

5. Ipari

Bọtini ti apẹrẹ PCB RF wa ni bii o ṣe le dinku agbara itankalẹ ati bii o ṣe le ṣe ilọsiwaju agbara kikọlu-egboogi. Ifilelẹ ti o ni ironu ati wiwu jẹ iṣeduro ti DESIGNING RF PCB. Ọna ti a ṣalaye ninu iwe yii ṣe iranlọwọ lati mu igbẹkẹle wa ti apẹrẹ PCB Circuit RF, yanju iṣoro ti kikọlu itanna, ati ṣaṣeyọri idi ti ibaramu itanna.