I roto i te meka, te papa poari panui (PCB) he mea hanga i nga raina hiko, ara kia mau tonu te aukati. Na he aha te PCB e whakauru ai i te koretake ki te tohu? Ko te whakautu ko te whakatakotoranga PCB he “mokowhiti kore-raina” e pa ana ki te waa e rere ana inaianei.

Ahakoa ka whakawhiwhia te kaitahuri mai i tetahi punaa tetahi atu ranei, kei te tiimata tonu o te tohu i runga i te utanga. Ka rere mai i tenei wa mai i te hiko hiko, ma te miihini pahi, na roto i te amplifier ki roto i te kawenga. 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. I roto i te papa rererangi whenua, he maha tonu atu i te kotahi te ara hikoiti-iti e rere ai te waahanga rahi o te whenua o te whenua: kotahi te ara e hono tika ana ki te pehanga pahi; Ko tetahi e whakaihiihi ana i te parenga whakauru kia tae ra ano te kaita hipa. Ko te Whakaahua 1 e whakaatu ana i enei huarahi e rua. Ko te ara whakamuri te mea e tino raru ana.

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Ka whakatauhia nga kaitaahiko hipa ki nga waahi rereke i runga i te PCB, ka rere te rere o te whenua ma nga huarahi rereke ki nga kaitaahiko whakawhiti, koinei te tikanga o te “korekore mokowhiti”. 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. Mena kaore i te awangawanga tetahi atu kutukutu o te au o te whenua, ka rereke te hiko o te tohu whakauru i roto i te momo kore. Ka hurihia tetahi waahanga polarity engari ko tetahi atu kaore i te, ka puta ke te rereketanga ka kitea ko te tuarua o te rereketanga o te tohu whakaputa. Ko te Whakaaturanga 2 e whakaatu ana i tenei ahuatanga rereke i te ahua rahi.

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Ina raru noa tetahi o nga waahanga o te ngaru sine, ko te ngaru hua kua kore he ngaru nui. Ko te whakaari i te kaiwhakawhana pai me te kawenga 100-ω me te hono i te taumaha o te kawenga na roto i te parenga 1-into ki roto i te ngaohiko o te whenua i runga noa i te kotahi o te tohu, ka puta te ahua 3. Fourier transform shows that the distortion waveform is almost all the second harmonics at -68 DBC. I nga iarere teitei, ko tenei reanga honoa ka ngawari te hanga ki runga i te PCB, ka taea te whakangaro i nga ahuatanga anti-distortion pai o te whakakaha me te kore e huri ki te nuinga o nga paanga motuhake kore o te PCB. 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

Ko te raru o nga maramara whakarei-maha (e rua, e toru, e wha ranei nga kaiwhakarei) ka whakahiatohia e te koretake ki te pupuri i te hononga whenua o te kaitaahiko hipa i tawhiti atu i te urunga katoa. He pono tenei mo nga whakarei e wha. Ko nga maramara tapahi-tapawha he taunga whakauru kei ia taha, na reira kaore he waahi mo nga huringa hipa e whakaiti ana i te awangawanga ki te waaawa whakauru.

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Ko te Whakaaturanga 5 e whakaatu ana i te huarahi ngawari ki te whakatakotoranga e wha-whakanui. Ko te nuinga o nga taputapu e hono tuuturu ana ki te pine quad amplifier. Ko te mana o te whenua o te mana hiko ka taea te whakararuraru i te ngaohiko whakauru whenua me te waa whenua o etahi atu hiko hiko, ka hua te rereke. Hei tauira, ko te (+ Vs) bypass capacitor kei te hongere 1 o te quad amplifier ka taea te whakanoho tata atu ki tana whakauru; Ka taea te whakanoho i te (-Vs) poraka peka ki tera taha o te kete. Ko te (+ Vs) papa whenua ka taea te whakararuraru i te hongere 1, i te mea kaore pea te (-vs) papa whenua.

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Hei karo i tenei raru, waiho ma te puna o te whenua e whakararu te whakauru, engari kia rere te PCB o naianei kia ahua tika te waahi. Hei whakatutuki i tenei, ka taea te whakarite i te miihini hipa ki runga i te PCB kia penei te rere o te (+ Vs) me te (- Vs) ma te ara ano. Mena he rereke te ahua o te tohu whakauru mai na te pai me te kino o te au, kaore e puta te rereke. Na, whakaarahia nga capacitor bypass e rua ki te taha o tetahi atu kia pai ai te tohatoha i tetahi tohu whenua. Na te mea ko nga waahanga e rua o te ao o te ao i ahu mai i te waahi kotahi (ko te hononga o te hononga ki te whakangungu rakau, ko te whenua kawenga ranei) ka rere ano te mea e rua ki te waahi kotahi (te hononga whenua noa o te kaitaahiko hipa), ka rere te pai / kino o te waa te ara ano. Mena kua pororaru te parenga whakaurunga o tetahi hongere e (+ Vs) o naianei, (- Vs) he penei ano te awangawanga o taua waa. 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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Hei whakamatau i nga korero o runga ake nei, e rua nga whakatakotoranga PCB rereke i whakamahia: he whakatakotoranga ngawari (Whakaahua 5) me te whakatakotoranga rereke-iti (Whakaahua 6). Ko te rereketanga i hangaia e te FHP3450 tapawha-mahi whakarahi e whakamahi ana i te semiconductor fairchild e whakaatuhia ana i te teepu 1. Ko te peenewhara angamaheni o te FHP3450 ko 210MHz, ko te pari ko 1100V / us, ko te kohinga whakauru e mau ana ko 100nA, a ko te waa whakahaere mo ia hongere he 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. Ae ra, ko te hongere kaiwhakawhana i whakawhiwhia ai ehara i te mea ko tana ake whakauru, engari ko te whakauru o etahi atu ara. The earth current flows through all the different channel inputs and produces different effects, but is influenced by each output, which is measurable.

Ko te ripanga 2 e whakaatu ana i nga mauritau kua whangangahia i runga i etahi atu hongere kore e peia ana kotahi te hongere e peia ana. Ko te hongere undriven e whakaatu ana i tetahi tohu iti (crosstalk) i te nui o te waa, engari ka whakaputa ano i te rereketanga i whakauruhia e te waa o te whenua i te korenga o etahi tohu waiwai nui. Ko te whakatakotoranga rerekee-iti i te Whakaahua 6 e whakaatu ana ko te tuarua o te taatai ​​me te katoa o te rereketanga o te rereketanga o te koti (THD) ka tino pai ake na te mea kua tata te whakakore i nga paanga o te whenua.

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Ko tenei whakarapopototanga tuhinga

Ma te korero noa, i runga i te PCB, ka rere te waa o muri ki nga capacitor rereke (mo nga mana hiko rereke) me te hiko hiko, e haangai ana ki tana kawe. Ko te tohu-auau tohu o naianei ka hoki ano ki te capacitor bypass iti. Nga auau iti-auau, peera i nga tohu oro, tera pea ka rere ma roto i nga hiko hiko hipa rahi ake. Ahakoa ko te auau auau o raro pea ka “wareware” i te kaha o te hipa, ka hoki tika ki te ara o te hiko. Ma te tono motuhake e tohu ko tehea ara te mea tino nui. 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.

Ko te ture koura mo te whakatakotoranga HF PCB ko te pupuri i te miihini hipa HF tata atu ki te pine mana takai e taea ana, engari ko te whakataurite o te Whakaahua 5 me te Whakaahua 6 e whakaatu ana ko te whakarereke i tenei ture hei whakapai ake i nga ahuatanga whakaparokore kaore e rereke. Ko nga ahuatanga rereke o te rereketanga i puta mai ma te utu ki te taapiri atu mo te 0.15 inihi o nga waea hiko tere-teitei, engari he iti nei te awe ki te mahi whakautu AC a te FHP3450. He mea nui te whakatakotoranga PCB ki te whakanui i te mahinga o te kounga teitei whakaohooho, ana ko nga take e korerohia ana i konei kaore e whaaiti noa ki nga amplifiers hf. Ko nga tohu auau o raro penei i te oro he uaua ake te whakarereke i nga whakaritenga. Ko te papa o naianei he iti ake i nga hautanga iti, engari akene he raru nui mena ka pai ake te taurangi rerekee e hiahiatia ana.