N’ezie, bọọdụ sekit biri ebi (PCB) ka ejiri ihe eletriki eletriki mee, ya bụ na mgbochi ha kwesịrị ịdị mgbe niile. Yabụ kedu ihe kpatara PCB ji ewebata ihe na -anọghị na akara? Azịza ya bụ na okirikiri nhọrọ ukwuu nke PCB bụ “nke na-abụghị ahịrị” dabere na ebe ọ na-aga.

Ma ampilifaya na -enweta ike site n’otu ebe ma ọ bụ ọzọ dabere na polarity nke mgbaàmà na ibu. Ugbu a na -esite na ọkụ ọkụ, site na capacitor gafere, site na ampilifaya banye na ibu. 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. N’ime ụgbọ elu nke ala, a na-enwekarị ihe karịrị otu ụzọ adịghị ike impedance nke nnukwu ala na-aga ugbu a: otu ụzọ jikọtara ya na capacitor uzo; Nke ọzọ na -atọ ụtọ resistor ndenye ruo mgbe agabigala capacitor gafere. Ọgụgụ 1 na -egosi ụzọ abụọ a. Ọgba azụ azụ bụ ihe kpatara nsogbu ahụ n’ezie.

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Mgbe etinyere ndị na -agafe agafe n’ọkwá dị iche iche na PCB, ala ugbu a na -agafe n’ụzọ dị iche iche na capacitors gafere, nke pụtara “enweghị ohere sara mbara”. 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. Ọ bụrụ na polarity ọzọ nke ala ugbu a agbaghasịghị, voltaji mgbaàmà ntinye na -agbanwe n’ụzọ adịghị. Mgbe agbanwere otu akụkụ polarity mana polarity nke ọzọ abụghị, agbagọ na -apụta ma gosipụta dị ka mgbagha nke abụọ nke mgbaàmà mmepụta. Ọgụgụ 2 na -egosi mmetụta mgbagọ a n’ụdị oke.

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Mgbe naanị otu akụkụ pola nke ebili mmiri sine na -akpaghasị, ntụgharị ihu na -esite na ya abụkwaghị ife efe. Ime simplifier dị mma nwere ibu 100-and na ijikọ ibu dị ugbu a site na onye na-eguzogide 1-into n’ime voltaji ala na naanị otu polarity nke mgbaama, na-ebute na onyonyo 3. Fourier transform shows that the distortion waveform is almost all the second harmonics at -68 DBC. N’ọtụtụ dị elu, a na-emepụta ọkwa a ngwa ngwa na PCB, nke nwere ike ibibi ezigbo njigide mgbagọ agbagọ nke amplifier na-ejighị ọtụtụ mmetụta pụrụ iche nke 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

Nsogbu nke ibe mgbawa ọtụtụ (abụọ, atọ, ma ọ bụ anọ) na-agbakọta site na enweghị ike idobe njikọ ala nke mgbachi capacitor dị anya na ntinye niile. Nke a bụ eziokwu maka amplifiers anọ. Mbadamba Quad-amplifier nwere ọdụ ntinye n’akụkụ nke ọ bụla, yabụ enweghị ohere maka sekit gafere nke na-ebelata ọgba aghara na ọwa ntinye.

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Ọgụgụ 5 na-egosi ụzọ dị mfe maka nhazi amplifier anọ. Ọtụtụ ngwaọrụ na -ejikọ ozugbo na pin amplifier quad. Ala nke otu ọkụ eletrik nwere ike mebie ndenye voltaji ala na ike ala nke ọkụ eletrik nke ọzọ, na -ebute mgbagọ. Dịka ọmụmaatụ, enwere ike idobe (+Vs) capacitor na ọwa 1 nke quad ampilifaya ozugbo n’akụkụ ntinye ya; Enwere ike idobe capacitor (-Vs) n’akụkụ nke ọzọ nke ngwugwu. Ala (+Vs) nwere ike mebie ọwa 1, ebe ala (-vs) nwere ike ọ gaghị.

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Iji zere nsogbu a, ka ala dị ugbu a na -agbagha ntinye ahụ, mana hapụ PCB ka ọ na -aga n’usoro n’usoro n’usoro. Iji mezuo nke a, enwere ike ịhazi capacitor na -agafe agafe na PCB n’ụzọ nke na (+Vs) na ( – Vs) na -asọba n’otu ụzọ ahụ. Ọ bụrụ na ebili mmiri na -adịghị mma na -agbagha mgbama ntinye, mgbagwọ agaghị apụta. Ya mere, dochie capacitors abụọ na -agafe n’akụkụ ibe ha ka ha wee nwee isi ala. N’ihi na akụkụ pola abụọ nke ụwa dị ugbu a na -esite n’otu ebe (njikọ njikọta mmepụta ma ọ bụ ala eburu ibu) na ha abụọ na -alaghachi n’otu ebe (njikọ ala nkịtị nke capacitor gafere), ihe dị mma/adịghị mma ugbu a na -agafe otu ụzọ ahụ. Ọ bụrụ na (+Vs) ugbu a na -enye nsogbu nkwụsị ọwa, ( – Vs) ugbu a nwere otu mmetụta na ya. 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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Iji nyochaa ntinye dị n’elu, ejiri PCB abụọ dị iche iche mee ihe: nhazi dị mfe (Ọgụgụ 5) na okirikiri okirikiri (eserese 6). Ngosipụta nke FHP3450 quad-ampilifaya na-arụ ọrụ site na iji semiconductor ngosi ka egosiri na tebụl 1. A na-egosi bandwidth FHP3450 bụ 210MHz, mkpọda bụ 1100V/anyị, ntinye ntinye ugbu a bụ 100nA, na arụ ọrụ ugbu a n’otu ọwa bụ 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. N’ụzọ doro anya, ọwa amplifier enyere na -akpaghasị ọ bụghị naanị ntinye nke ya, kamakwa ntinye nke ọwa ndị ọzọ. The earth current flows through all the different channel inputs and produces different effects, but is influenced by each output, which is measurable.

Tebụl 2 na -egosi harmonics a tụrụ na ọwa ndị ọzọ na -adịghị emebi emebi mgbe naanị otu ọwa na -anya. Ọwa a na -emezighị emezi na -egosipụta obere akara (crosstalk) na ugboro ugboro, mana ọ na -ewepụtakwa nrụrụ aka nke ala dị ugbu a webatara na enweghị akara ọ bụla dị mkpa. Nhazi agbagọ dị ala na eserese 6 na-egosi na njirimara harmonic nke abụọ na mkpokọta harmonic distortion (THD) na-akawanye nke ọma n’ihi na nso nso a na-ewepụ mmetụta ala dị ugbu a.

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Nchịkọta akụkọ a

N’ikwu ya n’ụzọ dị mfe, na PCB, azụ azụ na -aga site na capacitors uzo dị iche iche (maka ike dị iche iche) yana ike n’onwe ya, nke dabara na conductivity ya. Ihe mgbaàmà mgba ọkụ dị elu na-alaghachi na obere capacitor gafere. Okpokoro ala dị ala, dị ka nke ihe mgbaàmà ọdịyo, nwere ike na-asọfe site na nnukwu capacitors gafere. Ọbụlagodi obere oge ugbu a nwere ike ‘ileghara’ capacitance ngafe zuru oke wee laghachi ozugbo na ike ọkụ. Ngwa a kapịrị ọnụ ga -ekpebi ụzọ dị ugbu a kachasị mkpa. 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.

Ọchịchị ọla edo maka okirikiri nhọrọ ukwuu PCB HF bụ idobe HF gafere capacitor ka ọ dị nso ntụtụ ike nwere ike, mana ntụnyere nke eserese 5 na Ọgụgụ 6 na -egosi na imezi iwu a iji melite njirimara mgbagọ adịghị eme nnukwu ihe dị iche. Njirimara mgbagọ agbagoro bịara site n’ịgbakwunye ihe dị ka sentimita 0.15 nke eriri eletriki na-agafe ugboro ugboro, mana nke a nwere obere mmetụta na mmeghachi omume AC nke FHP3450. Nhazi PCB dị mkpa iji bulie arụmọrụ nke amplifier dị elu, na okwu ndị a tụlere ebe a abụghị naanị na hf amplifiers. Ihe mgbaàmà ugboro ugboro dị ka ụda nwere ihe mgbagwoju anya chọrọ. Mmetụta ala dị ugbu a pere mpe na obere oge, mana ọ ka nwere ike bụrụ nsogbu dị mkpa ma ọ bụrụ na emezigharị ndektọ mgbagọ chọrọ.