Ephrintiwe wesifunda ibhodi izinkinga ezinzima nezixazululo

Q: Njengoba kushiwo ngaphambili ngama-resistors alula, kufanele kube khona ezinye iziphikisi ukusebenza kwazo okuyikho kanye esikulindele. Kwenzekani ekumelaneni kwengxenye yocingo?
IMP: Isimo sihlukile. Ngokusobala ubhekisa ocingweni noma ibhendi eliqhubayo ebhodini lesifunda eliphrintiwe elisebenza njengocingo. Njengoba ama-superconductors asekamelweni lokushisa engakatholakali, noma yibuphi ubude bensimbi yensimbi busebenza njenge-resistor ephikisayo (nayo esebenza njenge-capacitor ne-inductor), nomphumela wayo esifundeni kufanele ubhekwe.
2. Q: Ukumelana nentambo yethusi emfushane kakhulu kusekethe yesiginali encane akumele kubaluleke?
A: ake sicabangele i-ADC engu-16-bit ene-impedance yokufaka engu-5k ω. Thatha ukuthi umugqa wesiginali kokufaka kwe-ADC uqukethe ibhodi lesifunda elijwayelekile eliphrintiwe (u-0.038mm ubukhulu, 0.25mm ububanzi) ngebhendi elihamba phambili elingu-10cm ubude. Inokumelana okungaba ngu-0.18 ω ekamelweni lokushisa, okungaphansi kuka-5K ω × 2 × 2-16 futhi kukhiqiza iphutha lokuzuza le-2LSB ngezinga eligcwele.
Ngokusobala, le nkinga ingancishiswa uma, njengoba sekuvele kunjalo, ibhendi eqhubayo yebhodi lesifunda elishicilelwe yenziwa yaba banzi. Kumasekethe we-analog, ngokuvamile kuncanyelwa ukusebenzisa ibhendi ebanzi, kepha abaklami abaningi be-PCB (nabaqambi be-PCB) bakhetha ukusebenzisa ububanzi bebhendi ubuncane ukwenza lula ukubekwa kolayini besiginali. Ekuphetheni, kubalulekile ukubala ukumelana kweqembu eliqhubayo nokuhlaziya indima yalo kuzo zonke izinkinga ezingaba khona.
3. Q: Ingabe kunenkinga nge-capacitance yebhendi eqhubayo enobubanzi obukhulu kakhulu nongqimba lwensimbi ngemuva kwebhodi lesifunda elinyathelisiwe?
A: Umbuzo omncane. Yize amandla we-capacitance avela ebhendi eqhubayo yebhodi lesifunda e-PRINTED ibalulekile (noma kumasekethe anemvamisa ephansi, engaveza ukukhishwa kwama-high-frequency parasitic oscillations), kufanele ihlale ilinganiselwa kuqala. Uma lokhu kungenjalo, ngisho neqembu elibanzi elenza i-capacitance enkulu akuyona inkinga. Uma kuvela izinkinga, indawo encane yebhanoyi lomhlaba ingasuswa ukunciphisa amandla emhlabeni.
Q: Shiya lo mbuzo okwesikhashana! Iyini indiza?
A: Uma ucwecwe lwethusi ohlangothini lonke lwebhodi lesifunda elinyathelisiwe (noma yonke i-interlayer yebhodi lesifunda ephrintiwe) lisetshenziselwa ukugxila, khona-ke yilokhu esikubiza ngokuthi yindiza yokuqinisa. Noma yiluphi ucingo lwaphansi luzohlelwa ngezinhlamvu ezincane kakhulu zokumelana nokuphazamiseka. Uma uhlelo lusebenzisa indiza ewela phansi, mancane amathuba okuthi luthintwe ngomsindo womhlaba. Ngaphezu kwalokho, indiza eyakhiwe phansi inomsebenzi wokuvikela nokupholisa
Q: Indiza yokubeka phansi eshiwo lapha inzima kubakhiqizi, akunjalo?
IMP: Kube nezinkinga ezithile eminyakeni engama-20 edlule. Namuhla, ngenxa yokuthuthuka kwe-binder, ukumelana kwe-solder nobuchwepheshe be-wave soldering kumabhodi wesekethe aphrintiwe, ukwenziwa kwendiza eyakhiwe kwaba umsebenzi ojwayelekile wamabhodi wesifunda aphrintiwe.
Q: Uthe ithuba lokuveza uhlelo emsindweni womhlabathi ngokusebenzisa indiza yaphansi lincane kakhulu. Yini okusele kwenkinga yomsindo womhlaba engakwazi ukuxazululwa?
IMP: Ukujikeleza okuyisisekelo kohlelo lomsindo olunezisekelo kunendiza yaphansi, kepha ukumelana kwayo nokungafakwanga kahle kwayo akuyona zero – uma umthombo wamanje wangaphandle unamandla ngokwanele, uzothinta amasiginali anembile. Le nkinga ingancishiswa ngokuhlela kahle amabhodi wesekethe aphrintiwe ukuze amandla aphezulu angagelezi aye ezindaweni ezithinta amandla okubeka amasignali wokunemba. Kwesinye isikhathi ukuphuka noma ukusikeka endizeni engaphansi kungaphambukisa umsinga omkhulu wokumisa endaweni ebucayi, kepha ukushintsha ngendiza ngenkani nakho kungaphambukisela isinali endaweni ebucayi, ngakho-ke inqubo enjalo kufanele isetshenziswe ngokunakekela.
Q: Ngazi kanjani ukuthi ukwehla kwamandla kagesi okwenziwe endizeni egxilile?
A: imvamisa ukwehla kwamandla kungalinganiswa, kepha kwesinye isikhathi izibalo zingenziwa ngokususelwa ekumelaneni kwento endizeni eyakhiwe i-conductive band lapho ukudlula kwamanje kudlula, yize izibalo zingaba nzima. Izilinganiso ezisebangeni le-dc kuya kumvamisa ophansi (1kHz) zingalinganiswa ngezikhulisi zomculo ezinjenge-AMP0 noma i-AD45.
Inzuzo yesikhulisi ibisethwe ku-1000 futhi ixhunywe kwi-oscilloscope enokuzwela kwe-5mV / div. I-amplifier ingahlinzekwa kusuka kumthombo wamandla ofanayo nowesifunda esivivinywayo, noma kumthombo wayo wamandla. Kodwa-ke, uma umhlaba wesikhulisi uhlukaniswe namandla awo, i-oscilloscope kufanele ixhunywe kusisekelo samandla wesekethe yamandla esetshenzisiwe.
Ukumelana phakathi kwanoma yimaphi amaphuzu amabili endizeni engaphansi kungalinganiswa ngokungeza iphenyo kulawa maphuzu amabili. Ukuhlanganiswa kwenzuzo ye-amplifier nokuzwela kwe-oscilloscope kwenza ukuzwela kwesilinganiso kufinyelele ku-5μV / div. Umsindo ovela ku-amplifier uzokhulisa ububanzi bejika le-oscilloscope waveform cishe nge-3μV, kepha kusenokwenzeka ukufeza isixazululo cishe se-1μV – esanele ukuhlukanisa umsindo omkhulu womhlaba ngokuzethemba okufika ku-80%.
Q: Yini okufanele iqashelwe ngale ndlela yokuhlola engenhla?
IMP: Noma iyiphi insimu kazibuthe eshintshanayo izodala amandla ombane ekuholeni kwephenyo, okungavivinywa ngokusabalalisa ama-probe komunye nomunye (nokunikeza indlela yokuphambuka ekumelaneni nomhlabathi) nokubuka isimo se-oscilloscope waveform. Ifomu le-AC elibhekiwe libangelwa ukufakwa futhi lingancishiswa ngokushintsha isikhundla sokuhola noma ngokuzama ukuqeda amandla kazibuthe. Ngaphezu kwalokho, kubalulekile ukuqinisekisa ukuthi isisekelo sesikhulisi sixhunywe kwisisekelo sohlelo. Uma i-amplifier inalokhu kuxhumana ayikho indlela yokubuyela emuva futhi i-amplifier ngeke isebenze. Ukwenza isisekelo kufanele futhi kuqinisekise ukuthi indlela yokusebenzisa isisekelo ayiphazamisi ukusatshalaliswa kwamanje kwesekethe ngaphansi kokuhlolwa.
Q: Ungayilinganisa kanjani imvamisa ephezulu yokususa umsindo?
A: Kunzima ukukala umsindo womhlaba we-hf ngesikhulisi se-wideband instrumentation amplifier, ngakho-ke i-hf ne-VHF probive probes zifanelekile. Iqukethe indandatho kazibuthe e-ferrite (ububanzi obungaphandle obungu-6 ~ 8mm) obunamakhoyili amabili angama-6 ~ 10 ajika ngalinye. Ukwenza i-transformer yokuhlukanisa imvamisa ephezulu, ikhoyili eyodwa ixhunywe kokufaka kwe-spectrum analyzer kanti enye kuphenyo.
Indlela yokuhlola iyefana nekesi lemvamisa eliphansi, kepha i-spectrum analyzer isebenzisa amajika wesici se-amplitude-frequency ukumela umsindo. Ngokungafani nezindawo zesizinda sesikhathi, imithombo yomsindo ingahlukaniswa kalula ngokuya ngezici zazo zemvamisa. Ngaphezu kwalokho, ukuzwela kwe-analyzer ye-spectrum okungenani i-60dB iphakeme kunaleyo ye-broadband oscilloscope.
Q: Kuthiwani ngokungeniswa kocingo?
A: Ukudonswa kwabaqhubi namabhendi e-PCB aqhubekekayo akunakushaywa indiva kumaza aphezulu. Ukuze ubale ukubanjiswa kwensimbi eqondile nebhendi eqhubayo, ukwethulwa okubili kwethulwa lapha.
Isibonelo, i-conductive band 1cm ubude no-0.25mm ububanzi izokwakha i-inductance ye-10nH.
Ukungenisa kwe-conductor = 0.0002LLN2LR-0.75 μH
Isibonelo, ukwehliswa kwentambo yobubanzi obungu-1cm ubude obungu-0.5mm ingu-7.26nh (2R = 0.5mm, L = 1cm)
I-Conductive band inductance = 0.0002LLN2LW + H + 0.2235W + HL + 0.5μH
Isibonelo, i-inductance ye-1cm ububanzi 0.25mm ephrintiwe yesigungu sebhodi eyi-9.59nh (H = 0.038mm, W = 0.25mm, L = 1cm).
Kodwa-ke, ukusabela okunyakazayo kuvame ukuba kuncane kakhulu kune-flux ye-parasitic namandla kagesi wesekethe we-inductive cut. Indawo yeluphu kufanele incishiswe ngoba i-voltage eyenziwe ilingana nendawo yeluphu. Lokhu kulula ukukwenza lapho izintambo zisontekile.
Emabhodini wesifunda aphrintiwe, izindlela zokuhola nezokubuya kufanele zisondelane. Izinguquko ezincane zezintambo zivame ukunciphisa umthelela, bona umthombo A ohlanganiswe namandla aphansi we-loop B.
Ukunciphisa indawo yokuvula noma ukukhulisa ibanga phakathi kwamaluphu wokuhlanganisa kuzonciphisa umphumela. Indawo ye-loop ivame ukwehliselwa kubuncane futhi ibanga phakathi kwamaluphu wokuhlanganisa likhulisiwe. Ukuvikelwa kwamagnetic kwesinye isikhathi kuyadingeka, kepha kuyabiza futhi kuvame ukwehluleka ngomshini, ngakho-ke kugweme.
11. Q: Ku-Q & A Yonjiniyela Bezicelo, ukuziphatha okungafanelekile kwamasekethe ahlanganisiwe kuvame ukushiwo. Kufanele kube lula ukusebenzisa izinto ezilula ezinjenge-resistors. Chaza ukusondela kwezakhi ezifanele.
IMP: Ngifuna nje ukuthi i-Resistor ibe yithuluzi elifanelekile, kepha isilinda esifushane ekuholeni kwe-resistor sisebenza njenge-Resistor emsulwa. Isiphikisi sangempela siqukethe nengxenye yokumelana nokucabanga – ingxenye yokusabela. Ama-resistors amaningi anamandla amancane (ngokujwayelekile i-1 kuye ku-3pF) ngokufana nokumelana kwawo. Yize amanye ama-resistors wamafilimu, ukusika kwe-helical groove kumafilimu awo aphikisayo kuthola kakhulu, ukusabela kwabo okungahambisani kahle kungamashumi noma amakhulu e-nahen (nH). Vele, ukumelana nezilonda zocingo kuvame ukuguquguquka kunokuba kube ne-capacitive (okungenani kumaza aphansi). Ngemuva kwakho konke, ama-resistor-wire-resistors enziwe ngamakhoyili, ngakho-ke akuyona into engavamile ukuthi ama-resistor wire-wound abe nokungeniswa kwama-microhm (μH) amaningi noma amashumi e-microhm, noma ngisho nama-resistors “engacindezeli” (lapho uhhafu wamakhoyili ulinyazwa ngokwewashi kanti enye ingxenye ihambisana nokuhamba kwewashi). Ukuze i-inductance ekhiqizwe yizingxenye ezimbili zekhoyili ikhansele enye nenye) nayo ine-1μH noma ngaphezulu kwe-inductance eyinsalela. Kwama-resistors wenani lentengo ephezulu ngenani elicishe libe ngu-10k ω, ama-resistor asele ikakhulukazi angama-capacitive kune-inductive, futhi amandla afinyelela ku-10pF, aphakeme kunalawo amafilimu ajwayelekile amancane noma ama-synthetic resistors. Lokhu kuphendula kufanele kucatshangelwe ngokucophelela lapho kuklanywa amasekethe aphezulu kakhulu aqukethe ama-resistors.
Q: Kepha amasekethe amaningi owachazayo asetshenziselwa izilinganiso eziqondile e-DC noma amaza aphansi kakhulu. Ama-inductors alahlekile nama-capacitor alahlekile awasebenzi kulezi zinhlelo, akunjalo?
A: yebo. Ngoba ama-transistors (womabili ahlukanisiwe naphakathi kwamasekethe ahlanganisiwe) anebubanzi obubanzi kakhulu bebhendi, ama-oscillations kwesinye isikhathi angavela kumakhulu noma izinkulungwane zamabhendi e-megahertz lapho isifunda siphela ngomthwalo ongenayo. Izenzo ze-offset nezokulungisa ezihambisana nokushayisana kunemiphumela emibi ekunemba kwemvamisa ephansi nasekuzinzeni.
Okubi kakhulu, ukukhishwa kwe-oscillations kungenzeka kungabonakali ku-oscilloscope noma kungenxa yokuthi umkhawulokudonsa we-oscilloscope uphansi kakhulu uma kuqhathaniswa nomkhawulokudonsa wokuphakama kwemvamisa ephezulu okulinganiswayo, noma ngoba umthamo wokushaja we-oscilloscope probe wenele ukumisa ukukhishwa. Indlela enhle ukusebenzisa ibhendi ebanzi (imvamisa ephansi kuya ku-15GHz ngenhla) i-spectrum analyzer ukubheka uhlelo lokushaywa yisinambuzane. Lokhu kuhlolwa kufanele kwenziwe lapho okokufaka kuyahlukahluka kulo lonke uhla olunamandla, ngoba ukukhishwa kwama-parasitic kwesinye isikhathi kwenzeka ebangeni elincane kakhulu lebhendi lokufaka.
Q: Ingabe ikhona imibuzo mayelana nama-resistors?
A: Ukumelana kwe-Resistor akulungisiwe, kepha kuyahlukahluka ngokushisa. I-coefficient lokushisa (TC) liyahlukahluka kusuka ku-PPM / ° C (millionths nge-degree Celsius ngayinye) kuya ezinkulungwaneni eziningana ze-PPM / ° C. Ama-resistors azinze kakhulu yizilonda zocingo noma izinsimbi zefilimu zensimbi, futhi okubi kakhulu yizinto zokuvikela ifilimu zekhabhoni.
Ama-coefficients wokushisa amakhulu kwesinye isikhathi angasebenziseka (isiphikisi esingu- + 3500ppm / ° C singasetshenziselwa ukunxephezela i-kT / Q ku-equation characteristic equation, njengoba kushiwo ngaphambili ku-Q & AS Yonjiniyela Bezicelo). Kepha ukumelana okujwayelekile nokushisa kungaba ngumthombo wephutha kumasekethe wokunemba.
Uma ukunemba kwesifunda kuncike kumdlalo wama-resistors amabili anama-coefficients wokushisa ahlukile, khona-ke noma ngabe angafaniswa kanjani ngokushisa okukodwa, ngeke afane nakwezinye. Noma kufana nokushisa kwama-coefficients wama-resistors amabili, asikho isiqiniseko sokuthi azohlala ezingeni lokushisa elifanayo. Ukuzifudumeza okwenziwe ngokusetshenziswa kwamandla kwangaphakathi noma ukushisa kwangaphandle okudluliswa kusuka kumthombo wokushisa ohlelweni kungadala ukungafani kokushisa, okuholele ekumelaneni. Ngisho nezinsimbi eziphakeme zensimbi noma isilonda sefilimu zingaba nokushisa okungafani kwamakhulu (noma ngisho nezinkulungwane) i-PPM / ℃. Isixazululo esisobala ukusebenzisa ama-resistors amabili akhiwe ukuze womabili asondele kakhulu ku-matrix efanayo, ukuze ukunemba kohlelo kufane kahle ngaso sonke isikhathi. I-substrate ingaba ngama-silicon wafers alingisa amasekethe ahlanganisiwe aqondile, amafers glass noma amafilimu ensimbi. Kungakhathalekile ukuthi i-substrate, ama-resistors amabili afana kahle ngenkathi kwenziwa, anama-coefficients wokushisa afaniswe kahle, futhi acishe afane nokushisa okufanayo (ngoba asondele kakhulu).