Kufananidza Impedance muHigh-Speed ​​​​PCB Layout

Inodzorwa impedance inomira seyakanyanya kutariswa mune yemazuva ano yakakwirira-kumhanya PCB dhizaini, ichiita basa rinokosha mukuona kutendeseka kwechiratidzo uye kuita kwese system. Ichi chinyorwa chakazara chinoongorora zvakadzika mune iyo pfungwa ye impedance, ichikurukura kuti impedance inorevei, kukosha kwayo muPCB dhizaini, uye nzira dzinoshandiswa kuwana uye kuchengetedza inodzorwa impedance mukati mekugadzira nekugadzira maitiro.

Kunzwisisa Impedance muPCB Dhizaini

Impedance, muchimiro chePCB dhizaini, inomiririra yakasanganiswa resistive, capacitive, uye inductive mhedzisiro inosangana nemagetsi chiratidzo painofamba ichitevedza conductive trace. Huwandu hwakaoma uhu, hunomiririrwa nemasvomhu naZ = √(R + jωL)² + (jωC)², hunosiyana nekuwanda nekuda kwekuchinja kwesimba rekuti inductance (L), kugona (C), uye kuramba (R) mukati mekutsvaga uye. zvakaipoteredza. Iyo dielectric inogara, kuteedzera upamhi, uye ukobvu zvese zvinotamba zvakakosha mukutaura iyo impedance mbiri yePCB yekufambisa tambo.

Izvo Zvinodikanwa zveKudzora Impedance

Kuderedza Chiratidzo Chiratidzo chakakosha-chinomhanya-mhanya chinoda nzira dzekutapurirana-dzinofananidzwa kudzivirira zviratidziro zvinokanganisa chiratidzo chepakutanga. Chero ipi zvayo impedance mismatch inoburitsa mafungu ekuratidzira anowedzera nekukwira frequency, kukanganisa nguva dzekusimuka, kuunza jitter, uye kuwedzera kukanganisa kukanganisa. Kuchengetedza inodzorwa impedance tracks saka inova nechokwadi chekuti masaini anonyudzwa pasina kukanganisa.

Shandisa peji rino kuti uwane zvinorehwa uye dudziro inoshanda yekufananidza impedance. Kuti uwane ruzivo rwakadzama uye gwara rekugadzira, ramba uchienzanisa impedance mukugadzira PCB nekukurumidza ; kuti uwane kugadzirwa kwakawanda, kuponi, uye ongororo yekutsungirira, shandisa peji reHighleap rekutonga impedance PCB service.

Kuve nechokwadi chekuenderana kweImpedance Mumasystem edhijitari neRF anomhanya zvakanyanya , masource, transmission line, uye load impedances zvinofanirwa kuenderana kuti zvive nechokwadi chekuti simba rinofambiswa zvizere. Zvikamu zvinowanzogadzirwa zvine ma impedance values ​​chaiwo (anowanzo kuve 50 Ω kana 100 Ω differential), zvichiita kuti pave ne impedance-controlled traces dzinobvumira kushandiswa kwakarurama kwe termination resistors. Misaligned impedance inotungamira kuma termination networks asingashande zvakanaka, zvichikanganisa kubatwa kwe high-speed transient edges.

Kuderedza Kubuda Kwemhepo muEMI Kusadzorwa kwemhepo kunowedzera EMI nekukurudzira kurasikirwa nekudzoka kwemafrequency akawanda uye mimhanzi inorira, izvo zvinogona kubatanidzwa mumasekete ari pedyo. Nzira dzekudzivirira mhepo dzinodzorwa zvakanaka dzinobatsira kuchengetedza masaini mukati menzira dzaunoda, nokudaro zvichideredza mwaranzi isingadiwe uye zvichiwedzera kutevedzera EMC yese.

Matanho eKuwana Kudzorwa Impedance

Vagadziri vanoshandisa akati wandei matekiniki ekumisikidza iwo emuviri ma paramita ePCB kuti uwane yakanangwa impedance kukosha:

• Kugadziriswa kweTrace Width Kuchinja upamhi hwemain conductor kunoita kuti baseline impedance value ive yekutanga, nepasuru dzakafara dzichideredza impedance uye dzakatetepa dzichiiwedzera, chero bedzi ukobvu hwemhangura huchiramba hwakafanana.

• Kugadziriswa kweDielectric Stackup Kusarudzwa kwemhando yezvinhu zve dielectric uye ukobvu zvinokanganisa zvakanyanya trace impedance nekuda kwe capacitance yazvinoita. Dielectric dzakatetepa kana dzakasimba dzinowanzo kukonzera impedance yakakwira.

• Kugadziriswa kweNdege yeReference Plane Mapurani epasi kana emagetsi ari pedyo anokanganisa trace impedance nekuchinja capacitance. Mapurani ari pedyo anoderedza impedance, nepo mapurani akaparadzaniswa achiiwedzera nekuda kwekudzikira kwekubatana.

• Kutarisira Kupatsanurwa Kwemakwara Kureba kuri pakati pemakwara ezviratidzo, mapedhi, kana nzvimbo dzakashama kunokanganisa kubatana, izvo zvinozosarudza kukosha kweimpedance. Kutarisira kwakanyatsonaka kwenzvimbo idzi kwakakosha pakudzora impedance.

Target Impedans Levels uye Tolerances

Zvinangwa zviviri zvekutanga zvekudzivirira zvinokunda mumagadzirirwo ePCB emazuva ano: 50 Ω yemasaini-agumirwa masaini uye 100 Ω yekusiyanisa vaviri nzira. Nekudaro, kuzadzisa zvinangwa izvi kunoda kuchenjerera stackup dimensioning uye chimiro chemidziyo, kuve nechokwadi chekudzora impedance pamatanho akasiyana siyana.

Zvinodiwa zvekushivirira zvinosiyana zvichienderana nekushandiswa. Semuenzaniso, kushivirira kwakanyanya (<±5-10 Ω) kwakakosha kune ekupedzisira-yepamusoro-kumhanya RF mabhodhi pamusoro pe5 Gbps, nepo ± 10% kusvika ± 15% inogamuchirwa kune yakaderera frequency dhijitari maseketi. Kunyangwe kudzora kwakasimba, zvinosiyana zvakaita semhangura ukobvu, dielectric kuumbwa, kuteedzera kuiswa, kunyoreswa kwedhizaini, uye kurongeka kwekugadzira kunogona kuramba kuunza kusvika ku ± 20% kusiyanisa mune impedance.

Kushandisa Impedance Kudzora Pakati Pemadhizaini Matanho

• Kutevedzera uye Kutevedzera Mamodheru ekufananidzira akaomarara anofanotaura kupindirana kwakavakirwa pakugadzirisa kwakarongwa kwezvikamu, zvichibvumira kuongororwa kwekutanga kwezvirongwa zvekugumisa uye kureba kwekutevera.

• Kuronga Stackup Tsanangudzo yakadzama yezvinhu zve laminate, prepregs, copper weights, uye layer sequencing inofanira kurongwa zvakanaka kuti isangane ne impedance targets uye zvinodiwa zvekuzviparadzanisa.

• Kufunga Nezvemarongero Vachitevedzera maparamita akadzorwa, mainjiniya emarongero vanotevedza marongero ane majometri akafanana munzvimbo dzakadzorwa dze dielectric, vachinyatso tarisa kureba kwemapairi akasiyana, kuburikidza nekuchinja, uye vachidzivirira ma angle akapinza e trace anokonzera kusagadzikana kwe impedance.

• Kugadzira Nekunyatsogadzirisa Maitiro ekugadzira anofanirwa kutevedzera mitemo yakasimba uye kuchengetedza kunyoreswa kwezvikamu. Makuponi ekuyedza anoshandiswa kuratidza kuenderera mberi kweimpedance muPCB yese.

• Kusimbiswa Kwekugadzirwa Mushure mekugadzirwa, ongororo ye impedance inoratidza chero kutsauka kunopfuura miganhu yakatarwa, zvichikurudzira kugadziriswa kwechimiro kana kuongororwazve kwefungidziro dzemaitiro.

Kusarudza Nguva Yokushandisa Kudzora Impedance

Kudzora impedance kunonyanya kukosha kune:

• Zviratidzo zveWachi Zviratidzo zvewachi zvine frequency yakakwira (>100 MHz) zvinoda kudzora impedance kuti zvideredze kukanganiswa kwese kwese, zvichiita kuti zvikamu zvakabatana zvishande pamwe chete.

• Nzira dzeData dzeSerializer/Deserializer (SerDes) Nzvimbo dzinoenderana dzeimpedance dzinosungirwa muzvisungo zveSerDes zvinomhanya zvakanyanya kuti zvidzivise kuratidzwa pakati pezvinhu zvinobva uye zvinoenda.

• Macircuit eAnalog Kuchengetedza kudzorwa kweimpedance mukutumira masaini eanalog kunobatsira kudziparadzanisa kubva kunzwi redhijitari, zvichichengetedza kuchena kwemasaini.

• Mabhazi Ekurangarira Mabhazi ekero/mirairo/data anosangana nemidziyo yekurangarira anobatsirwa nekutumira masaini enguva anoenderana neimpedance nemazvo panosvika chiteshi.

Kuve nechokwadi Inodzorwa Impedans muGerber Mafaira ePamusoro-Speed ​​PCB Kugadzira.

Pakugadzira mafaira eGerber ekugadzira PCB , mainjiniya eCAM anofanirwa kutarisa zvakanyanya pakuwana impedance inodzorwa kuti ichengetedze kusimba kwechiratidzo mumagadzirirwo ekumhanya kukuru. Impedance inodzorwa inobatsira kuderedza kuratidzwa kwechiratidzo kunogona kukanganisa mashandiro, ichiva nechokwadi chekuti masaini anopararira zvakanaka pasina kukanganisa kana kurasikirwa. Izvi zvinosanganisira kutarisisa zvakanyanya kuhupamhi hwetrace, zvinhu zve dielectric, uye layer stackups kuti zvisangane nezvinangwa zve impedance zvakatarwa zvakaita se50 Ω kana 100 Ω zve differential pairs. Matekiniki ekugadzira chaiwo uye verification ye impedance mushure mekugadzira zvakakosha kuchengetedza kuenderana uye kuvimbika muPCB yese, kunyanya munzvimbo dzinoda high-frequency signal fidelity uye kudzikira kwe electromagnetic interference ( EMI ).

Uyezve, mainjiniya eCAM anofanirwa kunyatso gadzirisa kushivirira kwedhizaini uye kushandisa maturusi ekufananidza kutarisira uye kugadzirisa kusiyana kwe impedance kutanga kwemaitiro ekugadzira. Nekuomerera kune aya maitiro, vanogona kuona kuti maPCB anosangana nekuomarara kwekuita zvinodiwa uye anokwanisa kutsigira epamberi emagetsi masisitimu nemazvo.

mhedziso

Kudzora kupindirana kunopa mabhenefiti akakosha mukugadzira PCB nekukurumidza , kudzivirira kubva mukuora kwechiratidzo, kukurudzira kugumisa kwechiratidzo zvakanaka, kuderedza EMI, uye kuona kuti data rakavimbika pabandwidths dzakakwirira. Sezvo huwandu hwedata huchiwedzera uye kudiwa kwekuvimbika kwechiratidzo che high-frequency kuchikura, hupamhi hwetrace, nzvimbo, uye kuronga layer zvinova zvakakosha zvikuru. Kuburikidza nekugadzira kwakanyatsonaka, simulation, uye kugadzirwa, kuiswa kwekudzivirira kunodzora kunovhura nzira yemaPCB akavimbika, anoshanda zvakanyanya anokwanisa kutsigira masisitimu emagetsi emazuva ano anonyanya kudiwa.