Raha ny tena izy, pirinty boribory pirinty (PCB) dia vita amin’ny akora mandeha amin’ny herinaratra, izany hoe tokony tsy ho tapaka ny fisakanany. Ka maninona ny PCB no mampiditra ny tsy fitoviana ho famantarana? Ny valiny dia ny layout PCB dia “sparally non-linear” mifandraika amin’ny ony ankehitriny.

Na ny amplifier dia mahazo ny onja avy amin’ny loharano iray na ny hafa dia miankina amin’ny polarity eo no ho eo ny famantarana amin’ny enta-mavesatra. Mikoriana avy amin’ny famatsiana herinaratra, amin’ny alàlan’ny capacitor bypass, amin’ny alàlan’ny amplifier mankany amin’ny entana. 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. Ao anaty fiaramanidina ambanin’ny tany, matetika dia misy lalana tsy mandeha amin’ny làlan-kaleha matetika izay misy ampahany lehibe amin’ny onjan-tany no mikoriana: lalana iray no mifandray mivantana amin’ny capacitor bypass; Ny iray hafa dia manentana ny resistor fidirana mandra-pahatongan’ny capacitor bypass. Ny sary 1 dia maneho ireo lalana roa ireo. Ny fivezivezena miverina no tena mahatonga ny olana.

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Rehefa apetraka amin’ny toerana samy hafa amin’ny PCB ny capacitors bypass dia mikoriana amin’ny lalan-kaleha mankany amin’ny capacitor bypass tsirairay ny onjan-bypass, izay midika hoe “nonlinearity spatial”. 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. Raha tsy mikorontana ny polarity hafa misy ny onja eto an-tany dia miova amin’ny fomba tsy mandeha ny volan’ny signal signal. Rehefa miova ny singa polarity iray fa ny iray hafa kosa tsy miova, dia misy ny fanodinkodinana ary miseho ho toy ny fanodikodinam-peo tononkira faharoa amin’ny famantarana output. Ny sary 2 dia mampiseho io fiovana io amin’ny endrika mihoapampana.

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Rehefa singa polar iray monja amin’ny onjan’ny sine no manakorontana, ny endrika onja vokatr’izany dia tsy onjam-peo intsony. Ny fanahafana ny amplifier mety tsara amin’ny enta-mavesatra 100-and ary ny fampifangaroana ny fatran’ny enta-mavesatra amin’ny alàlan’ny resistor 1-into ao anaty volteran’ny tany amin’ny polarity iray fotsiny an’ny signal, dia miteraka isa 3. Fourier transform shows that the distortion waveform is almost all the second harmonics at -68 DBC. Amin’ny haavo avo lenta, ity haavon’ny fitambarana ity dia mora azo avy amin’ny PCB, izay afaka manimba ny toetra manohitra ny fanodikodinam-bolo tena tsara amin’ny amplifier raha tsy manararaotra ny ankamaroan’ny vokatra tsy mivantana an’ny 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

Ny olan’ny poti-fanamafisam-peo (roa, telo na efatra fanamafisam-peo) dia ampiarahan’ny tsy fahaizana mitazona ny fifandraisana an-tanin’ny capacitor bypass lavitra ny fidirana iray manontolo. Tena marina izany ho an’ny amplifier efatra. Ny fantsom-pamokarana quad-amplifier dia misy fantsom-pifandraisana isaky ny lafiny, ka tsy misy toerana ho an’ny boribory bypass izay mampihena ny fikorontanan’ny fantsona fampiasa.

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Ny sary 5 dia mampiseho fomba tsotra amin’ny famolavolana efatra-amplifier. Ny ankamaroan’ny fitaovana dia mifandray mivantana amin’ny pin quad amplifier. Ny onjan-tany misy ny famatsiana herinaratra iray dia afaka manelingelina ny fidiran’ny tany sy ny onja misy ao amin’ilay famatsian-jiro hafa, ka miteraka fanodikodinana. Ohatra, ny (+ Vs) bypass capacitor amin’ny fantsona 1 an’ny quad amplifier dia azo apetraka eo akaikin’ny fidirana ao anatiny; Ny capacitor bypass (-Vs) dia azo apetraka amin’ny ilan’ny fonosana. Ny onjan-tany (+ Vs) dia mety hanelingelina ny fantsona 1, raha toa kosa ny ony (-vs) dia tsy mety.

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Mba hisorohana an’io olana io dia avelao ny onjan-tany hanakorontana ny fampidirana, fa avelao ny PCB amin’izao fotoana izao hikoriana amin’ny fomba madiodio. Mba hahatratrarana izany, ny capacitor bypass dia azo alamina amin’ny PCB amin’ny fomba izay mikoriana amin’ny lalana mitovy ihany ny (+ Vs) sy (- Vs). Raha toa ka sahiran-tsaina mitovy amin’ny onja tsara sy ratsy ny fambara fampidirana dia tsy hitranga ny fanodinkodinana. Noho izany, ampifanaraho mifanila ireo capacitors bypass roa mba hifampizaran’izy ireo ny teboka iray. Satria ny singa polar roa an’ny tany ankehitriny dia avy amin’ny teboka iray ihany (ny ampinga mpampitohy output na ny tany amn’ny enta-mavesatra) ary samy miverina miverina amin’ny teboka iray izy ireo (ny fifandraisana iraisana amin’ny capacitor bypass) dia mandeha ny ny lalana mitovy. Raha ny fikorontanan’ny fidirana amin’ny fantsona iray dia voakorontana amin’ny alàlan’ny (+ Vs) ankehitriny, (- Vs) dia misy vokany mitovy amin’izany koa ankehitriny. 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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Mba hanamarinana ilay inferansa etsy ambony, dia nisy layout PCB roa samy hafa nampiasaina: layout tsotra (sary 5) ary fisehosehoana ambany (sary 6). Ny fanodikodinam-bokatra vokarin’ny fanamafisam-peo quad-opération FHP3450 izay ampiasaina amin’ny semiconductor fairchild dia aseho amin’ny tabilao 1. Ny fantsom-pifandraisana mahazatra an’ny FHP3450 dia 210MHz, ny elanelam-bokatra dia 1100V / us, ny fidiran’ny bias ankehitriny dia 100nA, ary ny onja miasa isaky ny fantsona dia 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. Mazava ho azy fa ny fantsom-panafahana nomena dia tsy manelingelina ny fidirany fotsiny, fa ny fidiran’ny fantsona hafa koa. The earth current flows through all the different channel inputs and produces different effects, but is influenced by each output, which is measurable.

Ny tabilao 2 dia mampiseho ny harmonika refesina amin’ny fantsom-pahalalana tsy misy mpamindra hafa rehefa fantsona iray ihany no entina. Ny fantsona undriven dia mampiseho signal kely (crosstalk) amin’ny refy ifotony, nefa koa mamokatra fanodikodinam-bola nampidirin’ny onjan-tany mivantana raha tsy misy famantarana fototra lehibe. Ny endriny ambany fanodikodinam-bidy ao amin’ny sary faha-6 dia mampiseho fa ny toetran’ny fihavanana faharoa sy ny fanodikodinam-pihavanana (THD) dia nohatsaraina kokoa noho ny famongorana ny vokatry ny tany ankehitriny.

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Famintinana ity lahatsoratra ity

Raha tsorina, amin’ny PCB, ny onja miverina dia mivezivezy amin’ny alàlan’ny capacitors bypass (ho an’ny famatsian-tsolika samihafa) sy ny famatsian-jiro, izay mifanaraka amin’ny fitondraany. Ny onjam-peo haavo matetika dia miverina miverina amin’ny capacitor bypass kely. Ny onjam-peo ambany dia ambany, toa ny an’ireo fambara audio, dia mety mikoriana amin’ny alalàn’ny capacitor bypass lehibe kokoa. Na ny fatran’ny haavo ambany aza dia mety “tsy hiraharaha” ny capacitance bypass feno ary hikoriana mivantana mankany amin’ny fitarihana herinaratra. Ny fampiharana manokana dia hamaritra hoe iza no lalana manakiana indrindra. 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.

Ny fitsipika volamena ho an’ny layout HF PCB dia ny fitazonana ny capacitor bypass HF ho akaiky ny pin pouche pouvoir araka izay azo atao, fa ny fampitahana ny sary 5 sy ny sary 6 dia mampiseho fa ny fanovana an’io fitsipika io hanatsarana ny toetra mampivadika dia tsy mitondra fahasamihafana lehibe. Ny toetran’ny fanodikodinana nohatsaraina dia nanjary nandany vola tamin’ny fanampiana 0.15 santimetatra tamin’ny tariby capacitor bypass matetika, saingy tsy nisy fiatraikany firy tamin’ny valin’ny AC FHP3450. Ny layout PCB dia zava-dehibe mba hampitomboana ny fahombiazan’ny amplifier avo lenta, ary ny olana resahina eto dia tsy voafetra ho an’ny amplifiers hf. Ny fambara ambany matetika toy ny audio dia manana fitakiana fanodikodinana henjana kokoa. Ny vokatry ny tany ankehitriny dia kely kokoa amin’ny haavo ambany, fa mety mbola olana lehibe izany raha toa ka hatsaraina arak’izany ny index distortion takiana.