PCB gancang-gancang design refers to any design where the integrity of the signal begins to be affected by the physical characteristics of the PCB, such as layout, packaging, interconnect, and layer stacking. Furthermore, when you start designing boards and encounter problems such as delay, crosstalk, reflection, or emission, you will enter the field of high-speed PCB design.

The focus on these issues makes high-speed design so unique. Anjeun panginten biasa ngagunakeun PCB saderhana anu fokus kana panempatan komponén sareng kabel. However, when using high-speed designs, it is more important to consider factors such as their distance from the signal, the width of the signal, where they are placed and what kind of track they are. Patalina. Furthermore, with these factors in mind, it will reach a higher level in your PCB design process.

Kaparigelan desain PCB gancang

1. Know design software that offers advanced options

Peryogi seueur fungsi kompléks pikeun didesain dina perangkat lunak CAD kalayan gancang. Ogé, meureun henteu seueur program pikeun amatir, sareng sering aya pilihan anu langkung maju dumasar kana wéb Web. Kituna, anjeun peryogi pamahaman anu langkung saé pikeun alat CAD anu kuat.

2. Jalan tol

Nalika ngeunaan kabel gancang-gancang, désainer kedah ngartos aturan pikeun kabel dasar, kalebet henteu motong sambungan taneuh sareng ngajaga kabel pondok. Kusabab kitu, cegah crosstalk dina jarak anu tangtu dina garis digital sareng tameng sadaya generator gangguan supados henteu ngarusak integritas sinyal.

3. Cabling with impedance control

Kanggo sababaraha sinyal sakitar 40-120 ohm, peryogi cocog impedansi. The cue for characteristic impedance matching is the antenna and many difference pairs.

Penting pikeun desainer ngartos kumaha ngitung lebar garis sareng nilai impedansi anu diperyogikeun pikeun laminasi. Upami nilai impedansi henteu leres, sinyalna tiasa kapangaruhan parah, hasilna korupsi data.

4. Panjang cocog ngabasmi

Aya seueur garis dina beus mémori-gancang sareng beus antarbeungeut. Garis ieu tiasa beroperasi dina frékuénsi anu luhur pisan, janten penting pisan yén sinyal bakal indit sakaligus ti tungtung ngirim dugi ka tungtung panarima. Salaku tambahan, éta peryogi fitur anu disebut panjang cocog. Therefore, the most common standard defines the tolerance values that need to match the length.

5. Ngaleutikan daérah gelung

Désainer PCB gancang kedah terang sababaraha tip, sinyal frékuénsi luhur tiasa nyababkeun EMI, EMC sareng masalah sanés. Therefore, they need to follow basic rules, such as having continuous grounding and reducing loop area by optimizing the current return path of the wire, and putting in many suture holes.

Perkara peryogi perhatosan dina desain PCB gancang-gancang

PCB layout is very important

Tanpa ragu, manufaktur PCB épisién dina sirkuit gancang-gancang penting pikeun hasil tungtung. Nanging, tata ruang PCB henteu dianggap heula. Maka, éta bakal ngagaduhan pangaruh anu signifikan dina desain pikeun ngahontal fungsi anu diperyogikeun sareng manufaktur PCB anu suksés, sapertos perencanaan tingkat luhur sareng patuh kana faktor anu penting. Salaku tambahan, anjeun kedah ngabahas sababaraha masalah sateuacan perenah PCB, sapertos prakték desain pabrikan (DFM) sareng pertimbangan tambihan pikeun syarat PCB gancang-gancang.

Perenah anu goréng tiasa nyababkeun masalah kinerja nalika ngamimitian nguji atanapi nalika dianggo dina pembuatan PCB. To make matters worse, the need to evaluate PCB failures or performance issues and reassemble the prototype layout requires more cost and time to redesign or rework.

Notes for PCB design

In practice, high-speed PCB designs have many limitations for designers, as you need to meet various signal speed and other design requirements. Therefore, to achieve the high-speed circuit board design shown below, some factors need to be considered:

Schematic note: It is well known that a good schematic can lay a good foundation for PCB design. Therefore, depending on whether you are a PCB designer or an electrical engineer, the schematic diagram can be treated differently. Sacara umum, éta ngubaran skéma salaku alat komunikasi anu tiasa dihubungkeun sareng circuit board. But schematics can make a big difference in organizing and presenting your high-speed designs. Therefore, as much information as possible is available on the design schematic, such as wire length, necessary component placement, PCB manufacturer information, and so on.

Trace length adjustment: When using a high-speed interface, you need to adjust the trace length to synchronize the signal transmission with the data line. Nanging, panganteur na tiasa gagal dina frékuénsi maksimum, atanapi éta panginten henteu tiasa dianggo pisan sabab henteu disingkronkeun. Sumawona, langkung luhur frékuénsi antar muka, semakin tinggi persyaratan pencocokan panjangna. Ku alatan éta, dina kasus interfaces paralel, anjeun ngan kedah ngarobih panjang sadaya garis. It is important to be sure to adjust the length of these lines to get the desired length in a set of signals.

Bahan PCB sareng sarat pikeun tumpukan kecepatan tinggi: Ieu bakal mangaruhan desain gancang anjeun, sapertos struktur susun lapisan sareng bahan PCB.

Strategi panempatan gancang-gancang: Kusabab ngarobih ukuran pad sareng clearance komponén ngamaksimalkeun panjang sambungan gancang, éta tiasa dirarancang pikeun kecepatan luhur nganggo sababaraha cara pikeun ngaoptimalkeun panempatan komponén sareng ningkatkeun daérah padumukan komponén pikeun kagancangan.

Differential pairs and line-length routing: It is important to route differential pairs in high-speed designs so that pairs of signals can exist simultaneously.

Crosstalk, kontrol impedansi, sareng pertimbangan paralelisme: Dina desain gancang-gancang, aya seueur faktor anu tiasa mangaruhan desain anjeun. In addition, there are techniques to consider, such as how to minimize the impact on the design.

Understand ribbon and microstrip lines: In general, for high-speed designs, it requires multiple methods of routing. If highway routing is to be implemented, it is desirable to have a better understanding of strip and microstrip routing techniques.

Cabling topology and best cabling practices: Typically, a specific shape or topology is required if the circuit paths required for high-speed cabling are to be implemented. Also, it’s good to explore various ways to track line lengths, escapes, return paths, etc.

Simulator: Kanggo desain gancang-gancang, simulasi aya manpaat pisan sateuacan, salami, sareng saatos tata perenahna dimimitian. Therefore, you should have a better understanding of PCB design software to learn tips and tricks for simulation design.

Kumaha anjeun terang upami anjeun peryogi desain PCB gancang?

1. Is there a high-speed interface on the board?

A quick way to find out if you need to follow high-speed design guidelines is to check if you have high-speed interfaces, such as DDR, PCI-E, or even video interfaces, such as DVI, HDMI, etc.

Sadaya interfaces ieu kedah nuturkeun sababaraha aturan desain gancang-gancang. Salaku tambahan, punten nyayogikeun spésifikasi anu pasti pikeun unggal data dina dokuméntasi.

2. Ratio of trace length to signal wavelength

Sacara umum, upami panjang gelombang pesen anjeun sami sareng panjang garis, PCB anjeun pasti meryogikeun desain gancang-gancang. Kusabab sababaraha standar (sapertos DDR) ngabutuhkeun yén panjang garisna cocog sareng kasabaran minimum.

A good rough number is if your cable length and wavelength can be kept within an order of magnitude of each other. Teras, mangrupakeun ide anu saé pikeun parios desain gancang-gancang na.

3. PCB kalayan antarmuka nirkabel

Sakumaha anjeun terang, unggal PCB gaduh anténeu, sareng naha éta ngalangkungan konektor atanapi anu aya di papan tulis, sinyal gancang-gancang kedah dirarancang. Salaku tambahan, antena on-board peryogi impedansi ketat pikeun nyocogkeun sareng panjang tuning.

Pikeun papan anu nganggo konektor SMA atanapi konektor anu sami, anjeun kedah sambungkeun kana konektor kalayan nilai impedansi khusus.

kacindekan

In short, learning about high-speed PCB design depends on another project. Sanaos seueur faktor anu kedah diperhatoskeun nalika mendesain kagancangan gancang-gancang. Untungna, perangkat lunak CAD anu anjeun anggo pikeun desain PCB bakal nyayogikeun anjeun bantosan, sapertos kalkulator impedansi, pilihan ngalaporkeun panjangna rute, router pasangan diferensial, sareng alat-alat sanés.