Dhab ahaan, guddiga wareegsan oo daabacan (PCB) waxay ka samaysan yihiin qalab toosan oo koronto ah, yacni is -hortaagoodu waa inuu noqdaa mid joogto ah. Haddaba muxuu PCB ugu soo bandhigayaa calaamad aan toos ahayn? Jawaabtu waxay tahay in qaabka PCB-ga uu yahay “mid aan toos ahayn oo toosan” marka loo eego halka uu hadda socdo.

Haddii cod -weynehu uu hadda ka helo hal il ama meel kale waxay kuxirantahay is -beddelka deg -degga ah ee ishaarka saaran culeyska. Socodku hadda wuxuu ka socdaa korontada, iyada oo loo marayo capacitor -ka dhaafa, iyada oo loo sii kordhiyo culeyska. The current then travels from the load ground terminal (or shielding of the PCB output connector) back to the ground plane, through the bypass capacitor, and back to the source that originally supplied the current.

The concept of minimum path of current through impedance is incorrect. The amount of current in all different impedance paths is proportional to its conductivity. Diyaarad dhulka ah, inta badan waxaa jira in ka badan hal waddo-impedance hoose taas oo saamiga weyn ee dhulka hadda socda: hal waddo si toos ah ugu xiran capacitor bypass ah; Midda kale waxay ka farxisaa is -hortaagga soo -gelinta illaa inta laga gaadhayo capacitor -ka la dhaafo. Jaantuska 1 wuxuu muujinayaa labadan waddo. Dib -u -noqoshada dambe ayaa ah waxa runtii keenaya dhibaatada.

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Marka awood -mareennada la dhaafo lagu meeleeyo meelo kala duwan PCB -ga, dhulka hadda socdaa wuxuu maraa waddooyin kala duwan oo loo maro capacitors -ka kala -gudubka, taas oo ah macnaha “isku -dheelitirnaan -la’aanta”. If a significant portion of a polar component of the ground current flows through the ground of the input circuit, only that polar component of the signal is disturbed. Haddii kala -duwanaanta kale ee dhulka hadda aan la carqaladeyn, danab -gelinta is -beddelka is -beddelka ayaa u beddelaya qaab aan toos ahayn. Marka mid ka mid ah qaybaha polarity -ka la beddelo laakiin is -beddelka kale uusan ahayn, dhalanrog ayaa dhaca oo waxaa loo muujiyaa sida qaloocinta labaad ee is -beddelka ee soo -saarka soo -saarka. Jaantuska 2 wuxuu muujinayaa saamaynta dhalanrogkan oo ah qaab la buunbuuniyey.

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Marka kaliya hal qayb oo ka mid ah mawjadaha sine la dhibsado, mawjadda ka dhalatay ma aha mawjad sine. Ku-simidda cod-weyne-ku-habboon oo leh culeys 100-and ah iyo isku-xiridda culeyska hadda iyada oo loo marayo 1-ω resistor oo ku jira korantada dhulka oo kaliya hal polarity of signal, waxay ka dhalataa sawirka 3. Fourier transform shows that the distortion waveform is almost all the second harmonics at -68 DBC. Mowjadaha sare, heerkan isku-xirnaanta ayaa si fudud loogu soo saaraa PCB, kaas oo burburin kara astaamaha ka-hor-imaadka qaloocsan ee cod-weyne iyada oo aan loo adeegsan wax badan oo ah saamaynta aan tooska ahayn ee PCB-ga. When the output of a single operational amplifier is distorted due to the ground current path, the ground current flow can be adjusted by rearranging the bypass loop and maintaining distance from the input device, as shown in Figure 4.

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Multiamplifier chip

Dhibaatada jajabyada wax-weyneeyayaasha badan (laba, saddex, ama afar cod-weyne) waxaa sii dheer awood la’aanta ah in la sii wado isku-xidhka dhulka ee ka-soo-gudubka wareegga oo ka fog talooyinka oo dhan. Tani waxay si gaar ah run ugu tahay afar cod -weyne. Chips Quad-amplifier-ka ayaa dhinac walba leh boosteejooyin wax-soo-galineed, sidaa darteed ma jirto meel loogu talagalay wareegyada la dhaafo ee yareynaya khalkhalka kanaalka soo-gelinta.

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Jaantuska 5 wuxuu muujinayaa hab fudud oo loo adeegsado qaab-dhismeedka afar-weyne. Aaladaha badankood waxay si toos ah ugu xirmaan biin -weyne afar geesle ah. Socodka dhulka ee hal koronto ayaa khalkhal gelin kara korantada dhulka soo gelinta iyo socodka dhulka ee korontada kanaalka kale, taasoo dhalisa dhalanrog. Tusaale ahaan, (++Vs) capacitor -ka ka gudba kanaalka 1 ee kordhiyaha afaraad ayaa si toos ah loogu dhejin karaa soo -gelinta; (-Vs) capacitor-ku-dhaafka waxaa lagu dhejin karaa dhinaca kale ee xirmada. Xilliga dhulka (+Vs) wuxuu khalkhal gelin karaa kanaalka 1, halka (-vs) hadda dhulka uusan dhici karin.

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Si aad uga fogaato dhibaatadan, ha u oggolaato dhulka hadda inuu wareejiyo soo -gelinta, laakiin u oggolow PCB -ga hadda inuu u socdo qaab toosan oo toosan. Si taas loo gaaro, capacitor -ka gudbinta waxaa lagu diyaarin karaa PCB -ga si ay (+Vs) iyo ( – Vs) durdurrada dhulka u maraan isla waddada. Haddii calaamadda soo -gelinta ay si isku mid ah u carqaladeyso durdurrada togan iyo kuwa taban, dhalanrog ma dhici doono. Sidaa darteed, isku dheji labada koronto -ka -dhaaf ee is -ag -xiga si ay u wadaagaan dhibic dhulka ah. Sababtoo ah labada qaybood ee dabaysha dhulka hadda jira waxay ka yimaadaan hal dhibic (isku xiraha wax soo saarka gaashaanka ama dhulka culeyska) oo labaduba waxay ku noqdaan isla barta (isku xirka dhulka guud ee capacitor -ka), hadda togan/taban ayaa dhex mara isla wadadii. Haddii iska -caabbinta soo -gelinta kanaalka ay dhibsato (+Vs) hadda, ( – Vs) ayaa saamayn isku mid ah ku leh. Because the resulting disturbance is the same regardless of the polarity, there is no distortion, but a small change in the gain of the channel will occur, as shown in Figure 6.

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Si loo xaqiijiyo soo-jeedinta kor ku xusan, laba qaab-dhismeed PCB oo kala duwan ayaa la adeegsaday: qaab-dhismeed fudud (Jaantus 5) iyo qaab-qallooc hoose (Jaantuska 6). Dhalan-rogga ay soo saartay FHP3450 afar-kordhiyaha hawlgalka afar-hawlgal iyadoo la adeegsanayo semiconductor fairchild ayaa lagu muujiyey jadwalka 1. Baaxadda caadiga ah ee FHP3450 waa 210MHz, jiifku waa 1100V/annaga, eexda soo-jeedinta ee hadda waa 100nA, iyo kan hadda shaqeynaya kanaal kasta waa 3.6 mA. As can be seen from Table 1, the more distorted the channel, the better the improvement, so that the four channels are nearly equal in performance.

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Without an ideal quad amplifier on a PCB, measuring the effects of a single amplifier channel can be difficult. Sida iska cad, kanaalka wax -ku -oolka ah ee la siiyay ma khalkhaliyo oo keliya soo -jeedintiisa, laakiin gelinta kanaalada kale sidoo kale. The earth current flows through all the different channel inputs and produces different effects, but is influenced by each output, which is measurable.

Jadwalka 2 wuxuu muujinayaa iswaafajinta lagu cabbiray kanaallada kale ee aan duugoobayn marka hal kanaal oo keliya la wado. Kanaalka aan duugoobin wuxuu muujiyaa calaamad yar (crosstalk) inta jeer ee asaasiga ah, laakiin sidoo kale wuxuu soo saaraa dhalanrog si toos ah u soo bandhigay dhulka hadda jira iyada oo aysan jirin calaamad muhiim ah oo muhiim ah. Qaab-dhismeedka dhalan-rogga hoose ee Jaantuska 6 wuxuu muujinayaa in astaamaha isku-dhafka labaad iyo guud ahaan astaamaha dhalan-rogga (THD) si weyn loo hagaajiyay sababta oo ah meel-u-dhow baabi’inta saamaynta dhulka ee hadda jirta.

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Maqaalkan oo kooban

Si fudud marka loo dhigo, PCB -ga, qulqulka qulqulka qulqulaya wuxuu dhex maraa capacitors -ka kala -gudubka ee kala duwan (sahayda korontada kala duwan) iyo korontada lafteeda, taas oo u dhiganta hab -socodkeeda. Calaamadda soo noqnoqoshada sare ayaa hadda dib ugu soo noqota capacitor-ka yar ee la dhaafo. Mowjadaha soo noqnoqda ee hooseeya, sida kuwa dhawaaqa maqalka, ayaa laga yaabaa inay ugu horreeyaan dhex maraan awood-mareennada waaweyn. Xitaa soo -noqnoqoshada hoose ee hoose ayaa laga yaabaa inay “iska indho -tirto” awood -dhaafka buuxa oo si toos ah ugu laabato hoggaanka korontada. Arjiga gaarka ah ayaa go’aamin doona waddada hadda ugu muhiimsan. Fortunately, it is easy to protect the entire ground current path by using a common ground point and a ground bypass capacitor on the output side.

Xeerka dahabka ah ee HF PCB qaab -dhismeedkiisa ayaa ah in HF -ka wareejiyaha capacitor -ka uu u dhow yahay biinka awoodda baakadeysan ee suurtogalka ah, laakiin isbarbar dhigga Jaantuska 5 iyo Jaantuska 6 ayaa muujinaya in wax ka beddelidda qaanuunkan si loo hagaajiyo sifooyinka dhalanroggu uusan wax badan ka beddelin. Astaamaha dhalan-rogga ee la hagaajiyay waxay ku yimaadeen kharashkii lagu daray qiyaastii 0.15 inji oo xadhko xad-dhaaf ah oo xad-dhaaf ah, laakiin tani saamayn yar bay ku yeelatay waxqabadka jawaabta AC ee FHP3450. Qaab-dhismeedka PCB waa muhiim si loo kordhiyo wax-qabadka cod-weyne tayo sare leh, arrimaha halkan lagaga hadlay kuma koobna hf amplifiers. Calaamadaha soo noqnoqoshada hoose sida maqalka ayaa leh shuruudo dhalanrog oo aad u adag. Saamaynta dhulka ee hadda jirta ayaa ku yar inta jeer ee hooseysa, laakiin weli waxaa laga yaabaa inay tahay dhibaato muhiim ah haddii tusmada dhalanrog ee loo baahan yahay si hagaagsan loo hagaajiyo.