Moralo oa PCB oa Mixed-Signal: Ho itšehla thajana, ho Theha, le Maano a Taolo ea EMI

Selelekela

Ho kopanngoa ha dipotoloho tsa RF le tsa dijithale ho PCB e le nngwe ho se ho fetohile mokhoa o tlwaelehileng disebedisweng tsa sejwalejwale tsa IoT, di-module tsa puisano ya waelese, le ditsamaiso tse bohlale tsa di-sensor. Ho kopana hona ho sebetsana le ditlhoko tsa mmaraka tsa ditharollo tse nyane le tse theko e tlase ha ho ntse ho fana ka tshebetso e ntlafetseng. Leha ho le jwalo, moralo wa PCB wa matshwao a kopaneng o hlahisa diphephetso tse bohlokwa tsa botekgeniki: ho hokahana ha lerata pakeng tsa di-domain tsa potoloho, tshitiso ya motlakase, dikhohlano tsa ho thella, le botšepehi ba matshwao bo senyehileng.

Sengoliloeng sena se fana ka maano a sebetsang a ho fihlela ho itšehla thajana, ho kenya ts'ebetsong meralo e tiileng ea motheo, le ho laola EMI libakeng tse fapaneng tsa matšoao. Tsepamiso e ntse e le holim'a melao-motheo ea moralo e lokiselitsoeng tlhahiso e leka-lekaneng ts'ebetso ea motlakase le bokhoni ba tlhahiso.

Mathata a Motheo ho Moralo oa Mixed-Signal PCB

Litšobotsi tsa Sebaka sa Letšoao

Ho kopanngoa ha potoloho ea RF le ea dijithale ho baka likhohlano tse ka hare ka lebaka la litšobotsi tse fapaneng tsa lets'oao. Lipotoloho tsa RF li sebetsana le matšoao a maqhubu a tsoelang pele maqhubung a itseng, a hlokang ho bapisoa ho nepahetseng ha impedance le litlamorao tse fokolang tsa likokoana-hloko. Lipotoloho tsa dijithale li hlahisa liphetoho tse potlakileng ka litaba tse pharaletseng tsa harmonic tse atolohelang ho li-gigahertz ranges, tse hlahisang lerata le leholo la ho fetola le li-spikes tsa hona joale.

Mekhoa e ka Sehloohong ea Tšitiso

Litsela tse 'ne tsa bohlokoa tsa tšitiso li laola mathata a moralo oa PCB:

• Ho kopanya lerata la phepelo ea matla - Maqhubu a feto-fetohang a dijithale a fetola liporo tsa motlakase tse arolelanoang le methati e hlokolosi ea RF, e nyenyefatsang metrics ea ts'ebetso ea RF.
• Loops ea fatše - Litsela tse ngata tsa ho khutla li baka liphapang tse ka bang teng ho pholletsa le lifofane tsa litšupiso, li hlahisa li-voltage tse sa batleheng.
• Mahlaseli a EMI - Li-harmonics tsa dijithale tsa maemo a holimo li kopana ka lebaka la tšireletso e sa lekaneng kapa litšitiso tse sa lekaneng tsa ho itšehla thajana.
• Sefapano - Khokahano e matla le e susumetsang lipakeng tsa mesaletsa e haufi e fetisa lerata ho potoloha libaka.

Liphello tsa Botšepehi ba Pontšo

Mekhoa ena ea litšitiso e nyenyefatsa metrics ea ts'ebetso ea RF joalo ka palo ea lerata le lerata la karolo ha ka nako e ts'oanang e senya mephato ea nako ea dijithale. Ho utloisisa mekhoa ena ea ho kopanya 'mele ho theha motheo oa ho kenya ts'ebetsong maqheka a sebetsang a phokotso.

PCB Partitioning le Layout Isolation Techniques

Leano la ho arola le ts'ebetso

Moralo o sebetsang hantle oa li-signal-signal PCB o qala ka karohano e hlakileng ea 'mele ea RF, analog, le li-block tsa dijithale tse sebetsang. Sebopeho se lokela ho latela topology ea phallo ea mats'oao, ho beha liboloko ka tatellano ho tloha pheletsong e ka pele ea RF ho ea ho mekhahlelo ea maqhubu a mahareng ho isa ho ts'ebetso ea dijithale baseband. Tokisetso ena e fokotsa ho kopana ha morao mme e theha meeli ea tlhaho lipakeng tsa libaka tsa potoloho.

Lera Stack-up Planning

Mekhoa ea karohano ea PCB e atoloha ho ea kabong e otlolohileng, 'me likarolo tsa mats'oao a RF a arohaneng le mekhahlelo ea ho fetola dijithale ka lifofane tsa litšupiso tse inehetseng. Lipara tsa motlakase le tsa fatše li theha tšireletso e sebetsang ha li eme li bapile. Tsoelo-pele ea litšupiso tlas'a phetoho ea matšoao e ntse e le ea bohlokoa, kaha li-discontinuities li qobella maqhubu a khutlang ka litsela tse telele tse eketsang sebaka sa loop le mesi e hlahisoang ke mahlaseli.

Moqapi oa moeli oa RF-Digital

Moeli oa RF-digital o hloka tlhokomelo e hlokolosi moo mats'oao a fetang lipakeng tsa libaka. Litsela li lokela ho qoba ho tšela meeli ea karohano ntle le libakeng tse khethiloeng tsa phetoho, hangata libakeng tsa ADC kapa tsa DAC. Ha ho tšela ho bonahala ho ke ke ha qojoa, sebelisa lifaha tsa ferrite, li-filters tsa LC, kapa lithapo tsa phetisetso tse sirelelitsoeng ho boloka karohano ea domain.

Maqheka a ho Theha Moqapi oa PCB oa Mixed-Signal

Mokhoa o kopaneng oa Sefofane sa Lefatše

Moralo oa sejoale-joale oa li-signal tsa PCB o rata lifofane tse sa khaotseng tsa fatše tse nang le libaka tse hlalositsoeng hantle tsa phetoho ho fapana le ho arohana ka 'mele. Sefofane se kopantsoeng se boloka tsela e tlaase ka ho fetisisa ea ho khutlela morao bakeng sa likarolo tsohle tsa maqhubu ha se ntse se thibela liphapang tse ka 'nang tsa e-ba teng fatše tse hlaselang mehaho e arohaneng. Mokhoa ona o ipakile o phahametse maqhubu a kaholimo ho 1 MHz moo litlamorao tsa wavelength li busang.

Tsamaiso ea Tsela ea ho Khutlela fatše

Maqhubu a khutlang a RF a tlameha ho lula a lekanyelitsoe libakeng tsa potoloho ea RF ntle le ho phalla likarolong tsa dijithale. Fumana sena ka ho beha likarolo ka hloko le ka ho roka. Moralo oa fatše oa RF o kenyelletsa li-pass stitchings tse behiloeng ka nako ea kotara-wavelength ho potoloha mesaletsa ea RF, ho theha mabota a nang le maqhubu a khutlang ka har'a libaka tse khethiloeng.

Lintlha Tse Bohlokoa Tsa Phetoho

Libakeng tsa ADC le DAC moo libaka tsa analog le tsa dijithale li kopanang teng, theha leano la khokahano ea ntlha e le 'ngoe. Sefofane sa fatše sa analoge se lokela ho atoloha ka tlas'a IC eohle ea phetoho, se hokahane le sebaka sa digital feela sebakeng se inehetseng. Sebaka sena se hlalositsoeng se thibela ho potoloha ha maqhubu a fatše ha ho ntse ho boloka ts'ebetso ea DC fatše.

Karohano ea Phepelo ea Matla ka Moqapi oa PCB oa Mixed-Signal

Kabo e Ikemetseng ea Phepelo

Karohano ea phepelo ea motlakase e theha moeli oa bohlokoa oa ts'ireletso khahlano le tšitiso ea libaka tse fapaneng. Li-circuits tsa RF le tsa dijithale li lokela ho fumana matla ka lilaoli tse arohaneng tse theohang tlase kapa makala a phepelo a tlhotliloeng. Le ha e nkiloe ho motlakase o tloaelehileng oa ho kenya, taolo e ikemetseng e thibela ho fetoha ha dijithale ho tloha ho fetola liporo tsa phepelo ea RF.

Decoupling Network Design

Ts'ebetsong e nepahetseng ea ho kopanya e hloka hore ho behoe capacitor ka makhetlo a mangata:

• Bokhoni ba bongata (10-100 μF) - E sebetsana le meroalo e tlase ea maqhubu 'me e fana ka polokelo ea litefiso.
• Phetoho ea maqhubu a mahareng (0.1 μF) - Liaterese tse fetolang maqhubu ho tloha ho 100 kHz ho isa ho 10 MHz.
• Khokahano ea maqhubu a holimo (1-10 nF) - E shebana le lerata le phahameng haholo le maqhubu a switjha a kahare a IC.

Beha li-capacitor tsa maqhubu a phahameng ka har'a limilimithara tse 2 tsa lithapo tsa matla ho fokotsa ho kenella ha parasitic lupung ea hajoale.

Phatlalatso ea Network Optimization

Impedans ea marang-rang ea kabo ea matla e lokela ho lula e le ka tlase ho litekanyetso tse reriloeng ho li-frequency tsohle tsa ts'ebetso. Bakeng sa li-circuits tsa RF, boloka phepelo ea phepelo tlas'a 1Ω ka sehlopha sa ts'ebetso ho thibela ho feto-fetoha ha motlakase ho fetolelang ka kotloloho ho senyeha ha lerata.

Taolo ea EMI le Phokotso ea Crosstalk ho Moqapi oa PCB oa Mixed-Signal

Taeo ea ho tsamaisa

Metsamao ea RF e hloka tsela e laoloang ea impedance e nang le bolelele bo fokolang le litsela tse otlolohileng lipakeng tsa likarolo. Bala jiometri ea motsamao bakeng sa impedance e ikhethang ea 50Ω u sebelisa liparamente tsa stackup. Matšoao a dijithale a lebelo le phahameng a rua molemo mekhoeng ea ho tsamaisa e fapaneng e hlakolang mesi e tsoang libakeng tse hole. Boloka molao oa sebaka sa 3W pakeng tsa metsamao ea RF e bonolo le matšoao a dijithale a lerata.

Tšebeliso ea Tšireletso ea 'Mele

Taolo ea EMI moralong oa PCB oa matšoao a tsoakiloeng hangata e hloka tšireletso ea 'mele ka makotikoti a tšepe a behiloeng holim'a likarolo tsa potoloho tse bonolo. Makotikoti a tšireletso a tlameha ho hokahana le sefofane sa fatše ka li-vias tse ngata ho potoloha potoloho, ho theha li-enclosure tse tsoelang pele tsa motlakase. Bakeng sa meralo e nang le litšenyehelo tse tlase, nkela mesaletsa ea tšireletso sebaka kapa libaka tsa koporo tse tletseng fatše tse potolohileng likarolo tsa bohlokoa.

Taolo ea sekhahla sa moeli

Litefiso tsa moeli oa mats'oao a dijithale li supa ka kotloloho litaba tsa harmonic le EMI e hlahisoang. Fokotsa litheko ho ea ho boleng bo tlase bo amohelehang ba ts'ebeliso, ho fokotsa matla a maqhubu a phahameng ao banyalani ba kenang ho li-circuits tsa RF. Li-anti-termination resistants kapa li-IC tsa li-buffer tse laoloang li fokotsa sekhahla ntle le ho beha meeli ea nako e sebetsang.

Netefatso ea Moralo le Ketsiso bakeng sa Mixed-Signal PCB

Ketsiso ea Pre-Layout

Lisebelisoa tsa ketsiso ea matšoao a tsoakiloeng ho kenyeletsoa Keysight ADS, Ansys SIwave, le Altium Signal Integrity Analyzer li nolofalletsa netefatso ea pele ho tlhahiso ea liparamente tsa bohlokoa tsa moralo. Litsela tsa ho khutlisa mobu oa mohlala, impedance ea marang-rang a kabo ea matla, le ho hokahana pakeng tsa mesaletsa e haufi. Litlhahlobo tsena li khetholla mathata a ka bang teng nakong ea mohato oa moralo ha litokiso li ntse li le theko e tlase.

Netefatso ea Post-Layout

Tlhahlobo ea botšepehi ba matšoao e lokela ho netefatsa hore mesaletsa eohle e laoloang ea impedance e kopana le litlhaloso le hore litsela tsa morao-rao li lula li le teng. Ketsiso ea motlakase e senola kabo ea sekhahla sa hajoale mme e supa libaka tse hotspots tsa EMI tse hlokang phokotso e eketsehileng. Tlhahlobo ea botšepehi ba matla e tiisa ho arohana ho lekaneng ho pholletsa le mefuta e mengata ea ts'ebetso.

Ho netefatsa Hardware

Netefatso ea prototype e hloka litekanyo tsa spectrum analyser tsa mesi e tsamaisoang le ea mahlaseli. Bapisa liphetho khahlano le likhakanyo tsa papiso le litlhoko tsa moralo. Mekhoa ea ho hlahloba haufi-ufi e khetholla mehloli e itseng ea EMI ho PCB, e nolofalletsang lintlafatso tsa moralo bakeng sa lintlafatso tse latelang.

Ts'ebetsong ea Moralo oa PCB o Ts'ebetso e Ts'oanang ea Metsoako

Kopanyo Mohlala oa Meaho

Nahana ka mojule oa puisano o se nang mohala o kopanyang transceiver ea 2.4 GHz RF le microcontroller baseband processing. Sebopeho sa PCB se beha karolo ea RF moeling o le mong oa boto e nang le khokahano ea antenna, e lateloe ke likaroloana tsa analog IF, ebe li-converter tsa ADC/DAC moeling oa domain, 'me qetellong karolo ea digital microcontroller e lehlakoreng le leng.

Lintlha tse Bohlokoa tsa Moralo

Karolo ea RF e sebelisa likhoele tsa phetisetso ea li-waveguide tsa coplanar tse nang le lithupa tsa fatše tse fanang ka sephutheloana sa motlakase. Sefofane sa fatše se sa khaotseng se fetela ka har'a boto eohle ntle le ho khaola kapa ho arohana. Lisebelisoa tsa motlakase li arohane sethaleng sa LDO moo RF e fumanang taolo e inehetseng le ho sefa LC. Tšireletso ea tšepe e koahela likarolo tse peli tsa RF le tsa dijithale, tse hokahaneng fatše ka ho inehela ka terata.

Liphetho tse Lekanyelitsoeng tsa Ts'ebetso

Moralo ona oa moralo o kopaneng oa PCB hangata o fihlella karohano e fetang 60 dB lipakeng tsa RF le likarolo tsa dijithale, e boloka kutlo ea moamoheli oa RF ka har'a 1 dB ea meeli ea mohopolo. Mesi ea EMI e lula e le 10 dB ka tlase ho meeli ea taolo ntle le ho hloka ho sefa ho hoholo ha boemo ba boto, ho bonts'a katleho ea maano a kopaneng a ho itšehla thajana.

fihlela qeto e

Moralo o atlehileng oa PCB o ipapisitse le ts'ebetsong e hlophisehileng ea ho itšehla thajana, ho thea le ho sireletsa maano a thehiloeng nakong ea nts'etsopele ea meralo ea pele. Karohano ea 'mele e thibela mekhoa e mengata ea ho kopanya, ha motheo o kopantsoeng o nang le litsela tse laoloang tsa ho khutla o sebetsana le litsela tse setseng tsa tšitiso. Karohano ea phepelo ea motlakase le marang-rang a felletseng a ho kopanya a thibela ho kopanya lerata.

Highleap Electronics e fana ka bokhoni ba tlhahiso e nepahetseng bakeng sa ho batla lits'ebetso tse fapaneng tsa lipontšo:

• Tsela e laoloang ea impedance - Lipara tse fapaneng tse netefalitsoeng tsa 50Ω le 100Ω ka mamello ka hare ho ± 10% ho pholletsa le mabelo a tlhahiso.
• Li-stackups tse ntlafalitsoeng tsa multilayer - Litlhophiso tsa lera tse tloahelehileng tse leka-lekaneng litlhoko tsa botšepehi ba matšoao le litšenyehelo tsa tlhahiso.
• Phokotso e tsoetseng pele ea EMI - Ho roka fatše, litlhophiso tsa lera le sirelelitsoeng, le kopanyo ea mantlha ea tšepe bakeng sa ts'ebetso ea mocheso le motlakase.
• Tlhahiso ea RF e tšoanelehang - Thepa ea tahlehelo e tlase, jiometry e nepahetseng, le lits'ebetso tse netefalitsoeng tsa tlhahiso bakeng sa maqhubu ka 6 GHz.

Ikopanye le Highleap Electronics ho buisana ka litlhoko tsa hau tsa PCB tse tsoakiloeng le ho matlafatsa boenjiniere ba rona bakeng sa katleho ea moralo oa pele.