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compte</span></a></li><li id="pt-login" class="user-links-collapsible-item mw-list-item"><a href="/w/index.php?title=Especial:Registre_i_entrada&returnto=Imped%C3%A0ncia+d%27entrada" title="Us animem a registrar-vos, però no és obligatori [o]" accesskey="o"><span class="vector-icon mw-ui-icon-logIn mw-ui-icon-wikimedia-logIn"></span> <span>Inicia la sessió</span></a></li> </ul> </div> </div> <div id="p-user-menu-anon-editor" class="vector-menu mw-portlet mw-portlet-user-menu-anon-editor" > <div class="vector-menu-heading"> Pàgines per a editors no registrats <a href="/wiki/Ajuda:Introducci%C3%B3" aria-label="Vegeu més informació sobre l'edició"><span>més informació</span></a> </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="pt-anoncontribs" class="mw-list-item"><a href="/wiki/Especial:Contribucions_pr%C3%B2pies" title="Una llista de les modificacions fetes des d'aquesta adreça IP [y]" accesskey="y"><span>Contribucions</span></a></li><li id="pt-anontalk" class="mw-list-item"><a href="/wiki/Especial:Discussi%C3%B3_personal" title="Discussió sobre les edicions per aquesta adreça ip. [n]" accesskey="n"><span>Discussió per aquest IP</span></a></li> </ul> </div> </div> </div> </div> </nav> </div> </header> </div> <div class="mw-page-container"> <div class="mw-page-container-inner"> <div class="vector-sitenotice-container"> <div id="siteNotice"></div> </div> <div class="vector-column-start"> <div class="vector-main-menu-container"> <div id="mw-navigation"> <nav id="mw-panel" class="vector-main-menu-landmark" aria-label="Lloc"> <div id="vector-main-menu-pinned-container" class="vector-pinned-container"> </div> </nav> </div> </div> <div class="vector-sticky-pinned-container"> <nav id="mw-panel-toc" aria-label="Contingut" data-event-name="ui.sidebar-toc" class="mw-table-of-contents-container vector-toc-landmark"> <div id="vector-toc-pinned-container" class="vector-pinned-container"> <div id="vector-toc" class="vector-toc vector-pinnable-element"> <div class="vector-pinnable-header vector-toc-pinnable-header vector-pinnable-header-pinned" data-feature-name="toc-pinned" data-pinnable-element-id="vector-toc" > <h2 class="vector-pinnable-header-label">Contingut</h2> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-toc.pin">mou a la barra lateral</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-toc.unpin">amaga</button> </div> <ul class="vector-toc-contents" id="mw-panel-toc-list"> <li id="toc-mw-content-text" class="vector-toc-list-item vector-toc-level-1"> <a href="#" class="vector-toc-link"> <div class="vector-toc-text">Inici</div> </a> </li> <li id="toc-Impedància_d'entrada" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Impedància_d'entrada"> <div class="vector-toc-text"> <span class="vector-toc-numb">1</span> <span>Impedància d'entrada</span> </div> </a> <ul id="toc-Impedància_d'entrada-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Càlcul" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Càlcul"> <div class="vector-toc-text"> <span class="vector-toc-numb">2</span> <span>Càlcul</span> </div> </a> <ul id="toc-Càlcul-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Acoblament_d'impedàncies" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Acoblament_d'impedàncies"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Acoblament d'impedàncies</span> </div> </a> <ul id="toc-Acoblament_d'impedàncies-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Aplicacions" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Aplicacions"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Aplicacions</span> </div> </a> <ul id="toc-Aplicacions-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Referències" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Referències"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Referències</span> </div> </a> <ul id="toc-Referències-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contingut" class="vector-toc-landmark"> <div id="vector-page-titlebar-toc" class="vector-dropdown vector-page-titlebar-toc vector-button-flush-left" title="Taula de continguts" > <input type="checkbox" id="vector-page-titlebar-toc-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-titlebar-toc" class="vector-dropdown-checkbox " aria-label="Commuta la taula de continguts." > <label id="vector-page-titlebar-toc-label" for="vector-page-titlebar-toc-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--icon-only " aria-hidden="true" ><span class="vector-icon mw-ui-icon-listBullet mw-ui-icon-wikimedia-listBullet"></span> <span class="vector-dropdown-label-text">Commuta la taula de continguts.</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-titlebar-toc-unpinned-container" class="vector-unpinned-container"> </div> </div> </div> </nav> <h1 id="firstHeading" class="firstHeading mw-first-heading"><span class="mw-page-title-main">Impedància d'entrada</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Vés a un article en una altra llengua. Disponible en 14 llengües" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-14" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">14 llengües</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/Eingangswiderstand" title="Eingangswiderstand - alemany" lang="de" hreflang="de" data-title="Eingangswiderstand" data-language-autonym="Deutsch" data-language-local-name="alemany" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-en mw-list-item"><a href="https://en.wikipedia.org/wiki/Input_impedance" title="Input impedance - anglès" lang="en" hreflang="en" data-title="Input impedance" data-language-autonym="English" data-language-local-name="anglès" class="interlanguage-link-target"><span>English</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/Impedancia_de_entrada" title="Impedancia de entrada - espanyol" lang="es" hreflang="es" data-title="Impedancia de entrada" data-language-autonym="Español" data-language-local-name="espanyol" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D8%A7%D9%85%D9%BE%D8%AF%D8%A7%D9%86%D8%B3_%D9%88%D8%B1%D9%88%D8%AF%DB%8C" title="امپدانس ورودی - persa" lang="fa" hreflang="fa" data-title="امپدانس ورودی" data-language-autonym="فارسی" data-language-local-name="persa" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/%D7%A2%D7%9B%D7%91%D7%AA_%D7%9B%D7%A0%D7%99%D7%A1%D7%94" title="עכבת כניסה - hebreu" lang="he" hreflang="he" data-title="עכבת כניסה" data-language-autonym="עברית" data-language-local-name="hebreu" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-hi mw-list-item"><a href="https://hi.wikipedia.org/wiki/%E0%A4%A8%E0%A4%BF%E0%A4%B5%E0%A5%87%E0%A4%B6_%E0%A4%AA%E0%A5%8D%E0%A4%B0%E0%A4%A4%E0%A4%BF%E0%A4%AC%E0%A4%BE%E0%A4%A7%E0%A4%BE" title="निवेश प्रतिबाधा - hindi" lang="hi" hreflang="hi" data-title="निवेश प्रतिबाधा" data-language-autonym="हिन्दी" data-language-local-name="hindi" class="interlanguage-link-target"><span>हिन्दी</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/%E5%85%A5%E5%8A%9B%E3%82%A4%E3%83%B3%E3%83%94%E3%83%BC%E3%83%80%E3%83%B3%E3%82%B9" title="入力インピーダンス - japonès" lang="ja" hreflang="ja" data-title="入力インピーダンス" data-language-autonym="日本語" data-language-local-name="japonès" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/%EC%9E%85%EB%A0%A5_%EC%9E%84%ED%94%BC%EB%8D%98%EC%8A%A4" title="입력 임피던스 - coreà" lang="ko" hreflang="ko" data-title="입력 임피던스" data-language-autonym="한국어" data-language-local-name="coreà" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/Mateimpedans" title="Mateimpedans - noruec bokmål" lang="nb" hreflang="nb" data-title="Mateimpedans" data-language-autonym="Norsk bokmål" data-language-local-name="noruec bokmål" class="interlanguage-link-target"><span>Norsk bokmål</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Impedancja_wej%C5%9Bciowa" title="Impedancja wejściowa - polonès" lang="pl" hreflang="pl" data-title="Impedancja wejściowa" data-language-autonym="Polski" data-language-local-name="polonès" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/Imped%C3%A2ncia_de_entrada" title="Impedância de entrada - portuguès" lang="pt" hreflang="pt" data-title="Impedância de entrada" data-language-autonym="Português" data-language-local-name="portuguès" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%92%D1%85%D0%BE%D0%B4%D0%BD%D0%BE%D0%B9_%D0%B8%D0%BC%D0%BF%D0%B5%D0%B4%D0%B0%D0%BD%D1%81_%D0%B0%D0%BD%D1%82%D0%B5%D0%BD%D0%BD%D1%8B" title="Входной импеданс антенны - rus" lang="ru" hreflang="ru" data-title="Входной импеданс антенны" data-language-autonym="Русский" data-language-local-name="rus" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-uk mw-list-item"><a href="https://uk.wikipedia.org/wiki/%D0%92%D1%85%D1%96%D0%B4%D0%BD%D0%B8%D0%B9_%D1%96%D0%BC%D0%BF%D0%B5%D0%B4%D0%B0%D0%BD%D1%81_%D0%B0%D0%BD%D1%82%D0%B5%D0%BD%D0%B8" title="Вхідний імпеданс антени - ucraïnès" lang="uk" hreflang="uk" data-title="Вхідний імпеданс антени" data-language-autonym="Українська" data-language-local-name="ucraïnès" class="interlanguage-link-target"><span>Українська</span></a></li><li class="interlanguage-link interwiki-zh mw-list-item"><a href="https://zh.wikipedia.org/wiki/%E8%BE%93%E5%85%A5%E9%98%BB%E6%8A%97" title="输入阻抗 - xinès" lang="zh" hreflang="zh" data-title="输入阻抗" data-language-autonym="中文" data-language-local-name="xinès" class="interlanguage-link-target"><span>中文</span></a></li> </ul> <div class="after-portlet after-portlet-lang"><span class="wb-langlinks-edit wb-langlinks-link"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q1307489#sitelinks-wikipedia" title="Modificau enllaços interlingües" class="wbc-editpage">Modifica els enllaços</a></span></div> </div> </div> </div> </header> <div class="vector-page-toolbar"> <div class="vector-page-toolbar-container"> <div id="left-navigation"> <nav aria-label="Espais de noms"> <div id="p-associated-pages" class="vector-menu vector-menu-tabs mw-portlet mw-portlet-associated-pages" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="ca-nstab-main" class="selected vector-tab-noicon mw-list-item"><a href="/wiki/Imped%C3%A0ncia_d%27entrada" title="Vegeu el contingut de la pàgina [c]" accesskey="c"><span>Pàgina</span></a></li><li id="ca-talk" class="vector-tab-noicon mw-list-item"><a href="/wiki/Discussi%C3%B3:Imped%C3%A0ncia_d%27entrada" rel="discussion" title="Discussió sobre el contingut d'aquesta pàgina [t]" accesskey="t"><span>Discussió</span></a></li> </ul> </div> </div> <div id="vector-variants-dropdown" class="vector-dropdown emptyPortlet" > <input type="checkbox" id="vector-variants-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-variants-dropdown" class="vector-dropdown-checkbox " aria-label="Canvia la variant de llengua" > <label id="vector-variants-dropdown-label" for="vector-variants-dropdown-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet" aria-hidden="true" ><span class="vector-dropdown-label-text">català</span> </label> <div class="vector-dropdown-content"> <div id="p-variants" class="vector-menu mw-portlet mw-portlet-variants emptyPortlet" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> </ul> </div> </div> </div> </div> </nav> </div> <div id="right-navigation" class="vector-collapsible"> <nav aria-label="Vistes"> <div id="p-views" class="vector-menu vector-menu-tabs mw-portlet mw-portlet-views" > <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="ca-view" class="selected vector-tab-noicon mw-list-item"><a href="/wiki/Imped%C3%A0ncia_d%27entrada"><span>Mostra</span></a></li><li id="ca-edit" class="vector-tab-noicon mw-list-item"><a href="/w/index.php?title=Imped%C3%A0ncia_d%27entrada&action=edit" title="Modifica el codi font d'aquesta pàgina [e]" accesskey="e"><span>Modifica</span></a></li><li id="ca-history" class="vector-tab-noicon mw-list-item"><a href="/w/index.php?title=Imped%C3%A0ncia_d%27entrada&action=history" title="Versions antigues d'aquesta pàgina [h]" accesskey="h"><span>Mostra l'historial</span></a></li> </ul> </div> </div> </nav> <nav class="vector-page-tools-landmark" aria-label="Eines de la pàgina"> <div id="vector-page-tools-dropdown" class="vector-dropdown vector-page-tools-dropdown" > <input type="checkbox" id="vector-page-tools-dropdown-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-vector-page-tools-dropdown" class="vector-dropdown-checkbox " aria-label="Eines" > <label id="vector-page-tools-dropdown-label" for="vector-page-tools-dropdown-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet" aria-hidden="true" ><span class="vector-dropdown-label-text">Eines</span> </label> <div class="vector-dropdown-content"> <div id="vector-page-tools-unpinned-container" class="vector-unpinned-container"> <div id="vector-page-tools" class="vector-page-tools vector-pinnable-element"> <div class="vector-pinnable-header vector-page-tools-pinnable-header vector-pinnable-header-unpinned" data-feature-name="page-tools-pinned" data-pinnable-element-id="vector-page-tools" data-pinned-container-id="vector-page-tools-pinned-container" data-unpinned-container-id="vector-page-tools-unpinned-container" > <div class="vector-pinnable-header-label">Eines</div> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-pin-button" data-event-name="pinnable-header.vector-page-tools.pin">mou a la barra lateral</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-page-tools.unpin">amaga</button> </div> <div id="p-cactions" class="vector-menu mw-portlet mw-portlet-cactions emptyPortlet vector-has-collapsible-items" title="Més opcions" > <div class="vector-menu-heading"> Accions </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="ca-more-view" class="selected vector-more-collapsible-item mw-list-item"><a href="/wiki/Imped%C3%A0ncia_d%27entrada"><span>Mostra</span></a></li><li id="ca-more-edit" class="vector-more-collapsible-item mw-list-item"><a href="/w/index.php?title=Imped%C3%A0ncia_d%27entrada&action=edit" title="Modifica el codi font d'aquesta pàgina [e]" accesskey="e"><span>Modifica</span></a></li><li id="ca-more-history" class="vector-more-collapsible-item mw-list-item"><a href="/w/index.php?title=Imped%C3%A0ncia_d%27entrada&action=history"><span>Mostra l'historial</span></a></li> </ul> </div> </div> <div id="p-tb" class="vector-menu mw-portlet mw-portlet-tb" > <div class="vector-menu-heading"> General </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="t-whatlinkshere" class="mw-list-item"><a href="/wiki/Especial:Enlla%C3%A7os/Imped%C3%A0ncia_d%27entrada" title="Una llista de totes les pàgines wiki que enllacen amb aquesta [j]" accesskey="j"><span>Què hi enllaça</span></a></li><li id="t-recentchangeslinked" class="mw-list-item"><a href="/wiki/Especial:Seguiment/Imped%C3%A0ncia_d%27entrada" rel="nofollow" title="Canvis recents a pàgines enllaçades des d'aquesta pàgina [k]" accesskey="k"><span>Canvis relacionats</span></a></li><li id="t-permalink" class="mw-list-item"><a href="/w/index.php?title=Imped%C3%A0ncia_d%27entrada&oldid=32045929" title="Enllaç permanent a aquesta revisió de la pàgina"><span>Enllaç permanent</span></a></li><li id="t-info" class="mw-list-item"><a href="/w/index.php?title=Imped%C3%A0ncia_d%27entrada&action=info" title="Més informació sobre aquesta pàgina"><span>Informació de la pàgina</span></a></li><li id="t-cite" class="mw-list-item"><a href="/w/index.php?title=Especial:Citau&page=Imped%C3%A0ncia_d%27entrada&id=32045929&wpFormIdentifier=titleform" title="Informació sobre com citar aquesta pàgina"><span>Citau aquest article</span></a></li><li id="t-urlshortener" class="mw-list-item"><a href="/w/index.php?title=Especial:UrlShortener&url=https%3A%2F%2Fca.wikipedia.org%2Fwiki%2FImped%25C3%25A0ncia_d%2527entrada"><span>Obtén una URL abreujada</span></a></li><li id="t-urlshortener-qrcode" class="mw-list-item"><a href="/w/index.php?title=Especial:QrCode&url=https%3A%2F%2Fca.wikipedia.org%2Fwiki%2FImped%25C3%25A0ncia_d%2527entrada"><span>Descarrega el codi QR</span></a></li> </ul> </div> </div> <div id="p-coll-print_export" class="vector-menu mw-portlet mw-portlet-coll-print_export" > <div class="vector-menu-heading"> Imprimeix/exporta </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="coll-create_a_book" class="mw-list-item"><a href="/w/index.php?title=Especial:Llibre&bookcmd=book_creator&referer=Imped%C3%A0ncia+d%27entrada"><span>Crea un llibre</span></a></li><li id="coll-download-as-rl" class="mw-list-item"><a href="/w/index.php?title=Especial:DownloadAsPdf&page=Imped%C3%A0ncia_d%27entrada&action=show-download-screen"><span>Baixa com a PDF</span></a></li><li id="t-print" class="mw-list-item"><a href="/w/index.php?title=Imped%C3%A0ncia_d%27entrada&printable=yes" title="Versió per a impressió d'aquesta pàgina [p]" accesskey="p"><span>Versió per a impressora</span></a></li> </ul> </div> </div> <div id="p-wikibase-otherprojects" class="vector-menu mw-portlet mw-portlet-wikibase-otherprojects" > <div class="vector-menu-heading"> En altres projectes </div> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li id="t-wikibase" class="wb-otherproject-link wb-otherproject-wikibase-dataitem mw-list-item"><a href="https://www.wikidata.org/wiki/Special:EntityPage/Q1307489" title="Enllaç a l'element del repositori de dades connectat [g]" accesskey="g"><span>Element a Wikidata</span></a></li> </ul> </div> </div> </div> </div> </div> </div> </nav> </div> </div> </div> <div class="vector-column-end"> <div class="vector-sticky-pinned-container"> <nav class="vector-page-tools-landmark" aria-label="Eines de la pàgina"> <div id="vector-page-tools-pinned-container" class="vector-pinned-container"> </div> </nav> <nav class="vector-appearance-landmark" aria-label="Aparença"> <div id="vector-appearance-pinned-container" class="vector-pinned-container"> <div id="vector-appearance" class="vector-appearance vector-pinnable-element"> <div class="vector-pinnable-header vector-appearance-pinnable-header 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id="mw-content-subtitle"></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="ca" dir="ltr"><figure typeof="mw:File/Thumb"><a href="/wiki/Fitxer:Source_and_load_circuit_Z_(2).svg" class="mw-file-description"><img src="//upload.wikimedia.org/wikipedia/commons/thumb/7/78/Source_and_load_circuit_Z_%282%29.svg/377px-Source_and_load_circuit_Z_%282%29.svg.png" decoding="async" width="377" height="262" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/7/78/Source_and_load_circuit_Z_%282%29.svg/566px-Source_and_load_circuit_Z_%282%29.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/7/78/Source_and_load_circuit_Z_%282%29.svg/754px-Source_and_load_circuit_Z_%282%29.svg.png 2x" data-file-width="1164" data-file-height="808" /></a><figcaption>El circuit de l'esquerra del conjunt central de cercles oberts modela el circuit font, mentre que el circuit de la dreta modela el circuit connectat. <i>Z</i><sub>S</sub> és la impedància de sortida vista per la càrrega, i <i>Z</i><sub>L</sub> és la impedància d'entrada vista per la font.</figcaption></figure> <p>La <b>impedància d'entrada</b> d'una <a href="/wiki/Circuit_el%C3%A8ctric" title="Circuit elèctric">xarxa elèctrica</a> és la mesura de l'oposició al corrent (<a href="/wiki/Imped%C3%A0ncia" title="Impedància">impedància</a>), tant estàtica (<a href="/wiki/Resist%C3%A8ncia_el%C3%A8ctrica_i_conduct%C3%A0ncia" title="Resistència elèctrica i conductància">resistència</a>) com dinàmica (<a href="/wiki/React%C3%A0ncia" title="Reactància">reactància</a>), en una xarxa de <a href="/wiki/C%C3%A0rrega_el%C3%A8ctrica" title="Càrrega elèctrica">càrrega</a> <i>externa</i> a la xarxa de font elèctrica. L'<a href="/wiki/Admit%C3%A0ncia" title="Admitància">admitència</a> d'entrada (el <a href="/wiki/Invers_multiplicatiu" title="Invers multiplicatiu">recíproc</a> de la impedància) és una mesura de la propensió de la xarxa de càrrega a extreure corrent. La xarxa d'origen és la part de la xarxa que transmet energia i la xarxa de càrrega és la part de la xarxa que consumeix energia.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Impedància_d'entrada"><span id="Imped.C3.A0ncia_d.27entrada"></span>Impedància d'entrada</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Imped%C3%A0ncia_d%27entrada&action=edit&section=1" title="Modifica la secció: Impedància d'entrada"><span>modifica</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Si la xarxa de càrrega fos substituïda per un dispositiu amb una impedància de sortida igual a la impedància d'entrada de la xarxa de càrrega (circuit equivalent), les característiques de la xarxa font-càrrega serien les mateixes des de la perspectiva del punt de connexió. Per tant, la tensió a través i el corrent a través dels terminals d'entrada serien idèntics a la xarxa de càrrega escollida.<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> </p><p>Per tant, la impedància d'entrada de la càrrega i la impedància de sortida de la font determinen com canvien el corrent i la tensió de la font. </p><p>El circuit <a href="/wiki/Teorema_de_Th%C3%A9venin" title="Teorema de Thévenin">equivalent de Thévenin</a> de la xarxa elèctrica utilitza el concepte d'impedància d'entrada per determinar la impedància del circuit equivalent.<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Càlcul"><span id="C.C3.A0lcul"></span>Càlcul</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Imped%C3%A0ncia_d%27entrada&action=edit&section=2" title="Modifica la secció: Càlcul"><span>modifica</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Si es creés un circuit amb propietats equivalents als terminals d'entrada col·locant la impedància d'entrada a través de la càrrega del circuit i la impedància de sortida en sèrie amb la font del senyal, es podria utilitzar la <a href="/wiki/Llei_d%27Ohm" title="Llei d'Ohm">llei d'Ohm</a> per calcular la funció de transferència.<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Acoblament_d'impedàncies"><span id="Acoblament_d.27imped.C3.A0ncies"></span>Acoblament d'impedàncies</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Imped%C3%A0ncia_d%27entrada&action=edit&section=3" title="Modifica la secció: Acoblament d'impedàncies"><span>modifica</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Quan la impedància característica d'una <a href="/wiki/L%C3%ADnia_de_transmissi%C3%B3" title="Línia de transmissió">línia de transmissió</a>, <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle Z_{line}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>Z</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>l</mi> <mi>i</mi> <mi>n</mi> <mi>e</mi> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle Z_{line}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/e8dbefbd44214aac80673250b153bc1c8a5ad00d" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:4.63ex; height:2.509ex;" alt="{\displaystyle Z_{line}}" /></span>, no coincideix amb la impedància de la xarxa de càrrega, <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle Z_{in}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>Z</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>i</mi> <mi>n</mi> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle Z_{in}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/f535c2d4f2f03c883ad6425b802d68bbaa3cb91d" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:3.373ex; height:2.509ex;" alt="{\displaystyle Z_{in}}" /></span>, la xarxa de càrrega reflectirà part del senyal d'origen. Això pot crear <a href="/wiki/Ona_estacion%C3%A0ria" title="Ona estacionària">ones estacionàries</a> a la línia de transmissió. Per minimitzar les reflexions, la impedància característica de la <a href="/wiki/L%C3%ADnia_de_transmissi%C3%B3" title="Línia de transmissió">línia de transmissió</a> i la impedància del circuit de càrrega han de ser iguals (o "coincidir"). Si la impedància coincideix, la connexió es coneix com a <i>connexió coincident</i>, i el procés de correcció d'un desajust d'impedància s'anomena <i><a href="/wiki/Adaptaci%C3%B3_d%27imped%C3%A0ncies" title="Adaptació d'impedàncies">concordança d'impedància</a></i>.<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> Com que la impedància característica d'una línia de transmissió homogènia es basa només en la geometria i, per tant, és constant, i la impedància de càrrega es pot mesurar de manera independent, la condició de concordança es manté independentment de la ubicació de la càrrega (abans o després de la línia de transmissió). </p><p><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle Z_{in}=Z_{line}}"> <semantics> <mrow class="MJX-TeXAtom-ORD"> <mstyle displaystyle="true" scriptlevel="0"> <msub> <mi>Z</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>i</mi> <mi>n</mi> </mrow> </msub> <mo>=</mo> <msub> <mi>Z</mi> <mrow class="MJX-TeXAtom-ORD"> <mi>l</mi> <mi>i</mi> <mi>n</mi> <mi>e</mi> </mrow> </msub> </mstyle> </mrow> <annotation encoding="application/x-tex">{\displaystyle Z_{in}=Z_{line}}</annotation> </semantics> </math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/3ed55e49aeb773d988e8ce760ba8bbd13c106a76" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:11.102ex; height:2.509ex;" alt="{\displaystyle Z_{in}=Z_{line}}" /></span> </p> <div class="mw-heading mw-heading2"><h2 id="Aplicacions">Aplicacions</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Imped%C3%A0ncia_d%27entrada&action=edit&section=4" title="Modifica la secció: Aplicacions"><span>modifica</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>En <a href="/wiki/Processament_de_senyals" title="Processament de senyals">el processament de senyal</a> modern, els dispositius, com ara <a href="/wiki/Amplificador_electr%C3%B2nic" title="Amplificador electrònic">els amplificadors operacionals</a>, estan dissenyats per tenir una impedància d'entrada de diversos ordres de magnitud superior a la <a href="/wiki/Imped%C3%A0ncia_de_sortida" title="Impedància de sortida">impedància de sortida</a> del dispositiu font connectat a aquesta entrada. Això s'anomena <a href="/wiki/Pont_d%27imped%C3%A0ncia" title="Pont d'impedància">pont d'impedància</a>. Les pèrdues degudes a la impedància (pèrdua) d'entrada en aquests circuits es reduiran al mínim i la tensió a l'entrada de l'amplificador estarà propera a la tensió com si el circuit de l'amplificador no estigués connectat. Quan s'utilitza un dispositiu la impedància d'entrada del qual podria provocar una degradació important del senyal, sovint s'utilitza un dispositiu amb una impedància d'entrada alta i una impedància de sortida baixa per minimitzar els seus efectes. Sovint s'utilitzen transformadors de <a href="/w/index.php?title=Amplificador_buffer&action=edit&redlink=1" class="new" title="Amplificador buffer (encara no existeix)">seguiment de tensió</a> o d'adaptació d'impedància per a aquests efectes. </p> <div class="mw-heading mw-heading2"><h2 id="Referències"><span id="Refer.C3.A8ncies"></span>Referències</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Imped%C3%A0ncia_d%27entrada&action=edit&section=5" title="Modifica la secció: Referències"><span>modifica</span></a><span class="mw-editsection-bracket">]</span></span></div> <div class="reflist" style="list-style-type: decimal;"> <div class="mw-references-wrap"><ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><a href="#cite_ref-1">↑</a></span> <span class="reference-text"><span class="citation" style="font-style:normal">«<a rel="nofollow" class="external text" href="https://physics.bu.edu/adlab_and_elab/input-and-output-impedance/">Input and output impedance | Advanced Teaching Labs</a>» (en anglès).  <a rel="nofollow" class="external free" href="https://physics.bu.edu.+">https://physics.bu.edu.+</a>[Consulta: 11 juny 2023].</span></span> </li> <li id="cite_note-2"><span class="mw-cite-backlink"><a href="#cite_ref-2">↑</a></span> <span class="reference-text"><span class="citation" style="font-style:normal">«<a rel="nofollow" class="external text" href="https://www.electrical101.com/input-impedance.html">Input Impedance - Electrical 101</a>» (en anglès).  <a rel="nofollow" class="external free" href="https://www.electrical101.com.+">https://www.electrical101.com.+</a>[Consulta: 11 juny 2023].</span></span> </li> <li id="cite_note-3"><span class="mw-cite-backlink"><a href="#cite_ref-3">↑</a></span> <span class="reference-text"><span class="citation" style="font-style:normal">«<a rel="nofollow" class="external text" href="https://electronics.stackexchange.com/questions/21787/why-is-high-input-impedance-good">Why is high input impedance good?</a>» (en anglès).  <a rel="nofollow" class="external free" href="https://electronics.stackexchange.com.+">https://electronics.stackexchange.com.+</a>[Consulta: 11 juny 2023].</span></span> </li> <li id="cite_note-4"><span class="mw-cite-backlink"><a href="#cite_ref-4">↑</a></span> <span class="reference-text"><span class="citation" style="font-style:normal">«<a rel="nofollow" class="external text" href="https://www.powersystemsdesign.com/articles/input-impedance-measurements/18/5473">Input Impedance Measurements</a>» (en anglès).  <a rel="nofollow" class="external free" href="https://www.powersystemsdesign.com,+09-07-2012.+">https://www.powersystemsdesign.com,+09-07-2012.+</a>[Consulta: 11 juny 2023].</span></span> </li> <li id="cite_note-5"><span class="mw-cite-backlink"><a href="#cite_ref-5">↑</a></span> <span class="reference-text"><span class="citation" style="font-style:normal">«<a rel="nofollow" class="external text" href="https://www.nextpcb.com/blog/understanding-of-input-impedance-and-output-impedance">Understanding of input impedance and output impedance</a>» (en anglès).  <a rel="nofollow" class="external free" href="https://www.nextpcb.com.+">https://www.nextpcb.com.+</a>[Consulta: 11 juny 2023].</span></span> </li> </ol></div></div>    </div><noscript><img src="https://auth.wikimedia.org/loginwiki/wiki/Special:CentralAutoLogin/start?useformat=desktop&type=1x1&usesul3=1" alt="" width="1" height="1" style="border: none; position: absolute;"></noscript> <div class="printfooter" data-nosnippet="">Obtingut de «<a dir="ltr" href="https://ca.wikipedia.org/w/index.php?title=Impedància_d%27entrada&oldid=32045929">https://ca.wikipedia.org/w/index.php?title=Impedància_d%27entrada&oldid=32045929</a>»</div></div> <div id="catlinks" class="catlinks" data-mw="interface"><div id="mw-normal-catlinks" class="mw-normal-catlinks"><a href="/wiki/Especial:Categorias" title="Especial:Categorias">Categoria</a>: <ul><li><a href="/wiki/Categoria:Electr%C3%B2nica" title="Categoria:Electrònica">Electrònica</a></li></ul></div></div> </div> </main> </div> <div class="mw-footer-container"> <footer id="footer" class="mw-footer" > <ul id="footer-info"> <li id="footer-info-lastmod"> La pàgina va ser modificada per darrera vegada el 26 juny 2023 a les 11:14.</li> <li id="footer-info-copyright">El text està disponible sota la <a href="/wiki/Viquip%C3%A8dia:Text_de_la_llic%C3%A8ncia_de_Creative_Commons_Reconeixement-Compartir_Igual_4.0_No_adaptada" title="Viquipèdia:Text de la llicència de Creative Commons Reconeixement-Compartir Igual 4.0 No adaptada"> Llicència de Creative Commons Reconeixement i Compartir-Igual</a>; es poden aplicar termes addicionals. 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