{"id":1898,"date":"2013-06-06T11:58:29","date_gmt":"2013-06-06T02:58:29","guid":{"rendered":"https:\/\/micronix-jp.com\/?p=1898"},"modified":"2024-09-04T11:23:42","modified_gmt":"2024-09-04T02:23:42","slug":"map3012technicalreport1e","status":"publish","type":"post","link":"https:\/\/micronix-jp.com\/english\/tech\/technology\/map3012technicalreport1e.html","title":{"rendered":"Relation between noise level and noise figure NF"},"content":{"rendered":"<p><\/p><p>For example, the input signal is amplified 20dB whe n it passes an amplifier of 20dB gain. This is understandable.<br>\nHow about a noise ?&nbsp;<i class=\"fas fa-arrow-right\" aria-hidden=\"true\"><\/i>&nbsp;This cannot be understood well.<\/p><p>That is, the appearance of signal is same if a noise is also amplified 20dB when a signal is amplified 20dB? <\/p><figure class=\"wp-block-image\"><img decoding=\"async\" src=\"\/eng\/image\/technology\/MAP3012TechnicalReport1e-00.gif\" alt=\"Figure: How the signal looks\"\/><\/figure><p><span class=\"fontRed\">It's wrong. <\/span>Let's consider the definition of noise figure NF.<\/p><div class=\"borderBoxAuto\">\nNF is a ratio of input S\/N to output S\/N.<br>\nNF(dB)=20log[(Si\/Ni)\/(So\/No)]\n<ul>\n  <li>Si,So:signal level of input and output<\/li>\n  <li>Ni,No:noise level of input and output<\/li>\n  <\/ul>\n<\/div><p>\n<i class=\"fas fa-arrow-down fa-4x\" aria-hidden=\"true\" style=\"margin:0 2em\"><\/i>\n<\/p><div class=\"borderBoxAuto\">\n<p>&lt;Meaning of NF&gt;<\/p>\n<ol>\n  <li>A ratio of input S\/N to output S\/N.<\/li>\n  <li>Output S\/N is reduced only NF(dB) from input S\/N.<\/li>\n<li> Output noise No \uff1d Ni \uff0b G \uff0b NF  ......  G,NF and Ni should be dB. <\/li>\n<\/ol>\n\n<\/div><p>Let's explain concretely.<\/p><ul class=\"wp-block-list\"><li>Input signal level  Si=-100dBm<\/li>\n\n<li>Input noise level  Ni=-150dBm<\/li>\n\n<li>Amplifier gain =20dB <\/li>\n\n<li>NF of amplifier=3.5dB <\/li><\/ul><p>With the above conditions, the output will be as sh\nown in the figure below because of &lt;Meaning of NF&gt;3mentioned above.<\/p><figure class=\"wp-block-image\"><img decoding=\"async\" src=\"\/eng\/image\/technology\/MAP3012TechnicalReport1e-01.gif\" alt=\"Figure: The meaning of NF\"\/><\/figure><p>\n\n\n$$\n\\begin{cases}\n\\text{Input}~S\/N=-100-(-150)=50dB\\\\\n\\text{Output}~S\/N=-80-(-126.5)=46.5dB\n\\end{cases}\n$$\n\n$$\n\\begin{align}\n\u2234NF&amp;=(\\text{Input}~S\/N~50dB)-(\\text^{Output}~S\/N~46.5dB)\\\\\n&amp;=3.5dB \u2190 \\text{Indeed, &lt;Meaning of NF&gt;2 is established.}\n\\end{align}\n$$\n\n\n\n<\/p><p><span class=\"fontRed\">Output S\/N is reduced only NF(dB) from input S\/N.<\/span>This's an important point.<\/p><p>Then, the signal and noise at input and output shall be observed with a spectrum analyzer.<br>\nThe noise level of a spectrum analyzer assumes -110dBm.<\/p><ul class=\"wp-block-list\"><li><img loading=\"lazy\" decoding=\"async\" width=\"353\" height=\"181\" src=\"\/eng\/image\/technology\/MAP3012TechnicalReport1e-02.gif\" alt=\"Relation between noise level and noise figure NF\"><\/li>\n\n<li>Although the input S\/N is 50dB, S\/N gets worese to 10dB when observed with a spectrum analyzer.<br><br>Only 10dB from noise level is visible.<\/li><\/ul><ul class=\"wp-block-list\"><li><img loading=\"lazy\" decoding=\"async\" width=\"410\" height=\"292\" src=\"\/eng\/image\/technology\/MAP3012TechnicalReport1e-03.gif\" alt=\"Relation between noise level and noise figure NF\"><\/li>\n\n<li>Although the output S\/N is 46.5dB, S\/N gets worse to 30dB when observed with a spectrum analyzer.<br><br>However, it's 20dB better than input S\/N.<\/li><\/ul><p>When observed with a spectrum analyzer, the appearance of spectrum is related greatly to that noise level. <\/p><p class=\"has-text-align-left\">Case Study\uff1a<\/p><p>To verify the effect of the pre-amplifier, following connection of the signal generator, the pre-amplifier MAP301\/302 and signal analyzer MSA538 is established. We made the measurement of the signal to noise ration and gain for each signal path. The setting of equipments is as follows. <\/p><ul class=\"wp-block-list\"><li>Signal Generator<ul class=\"wp-block-list\"><li>Frequency:100MHz<\/li>\n\n<li>Output Level:-92dBm<\/li><\/ul><\/li>\n\n<li>Signal Analyzer<ul class=\"wp-block-list\"><li>Center Frequency:100MHz<\/li>\n\n<li>Span:20MHz<\/li>\n\n<li>Reference Level:-30dBm<\/li>\n\n<li>RBW :  100kHz<\/li>\n\n<li>VBW :  30kHz<\/li><\/ul><\/li><\/ul><figure class=\"wp-block-image\"><img decoding=\"async\" src=\"\/eng\/image\/technology\/MAP3012TechnicalReport1e-04.gif\" alt=\"Relation between noise level and noise figure NF\"\/><\/figure><p>The measurement results are shown in bellow.<\/p><figure class=\"wp-block-table\"><table><tbody><tr><th>Connection<\/th><th>Gain [dB]<\/th><th>S\/N Ratio [dB]<\/th><\/tr><tr><td>No Amplifier<\/td><td>0<\/td><td>10<\/td><\/tr><tr><td>MAP301<\/td><td>52<\/td><td>27<\/td><\/tr><tr><td>MAP302<\/td><td>21<\/td><td>21<\/td><\/tr><\/tbody><\/table><\/figure><p>No Amplifier<\/p><figure class=\"wp-block-image\"><img decoding=\"async\" src=\"\/eng\/image\/technology\/MAP3012TechnicalReport1e-05.gif\" alt=\"No Amplifier\"\/><\/figure><p>MAP301<\/p><figure class=\"wp-block-image\"><img decoding=\"async\" src=\"\/eng\/image\/technology\/MAP3012TechnicalReport1e-06.gif\" alt=\"MAP301\"\/><\/figure><p>MAP302<\/p><figure class=\"wp-block-image\"><img decoding=\"async\" src=\"\/eng\/image\/technology\/MAP3012TechnicalReport1e-07.gif\" alt=\"MAP302\"\/><\/figure><p>It is confirmed that we can improve the S\/N ratio by using appropriate pre-amplifier.<\/p><h2 class=\"wp-block-heading\">Products introduction<\/h2><div class=\"wp-block-vk-blocks-select-post-list vk_posts vk_posts-postType-post vk_posts-layout-card-noborder vk_postList\"><div id=\"post-5802\" class=\"vk_post vk_post-postType-product card card-noborder vk_post-col-xs-12 vk_post-col-sm-6 vk_post-col-md-3 vk_post-col-lg-3 vk_post-col-xl-3 vk_post-col-xxl-3 post-1898 post type-post status-publish format-standard 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This is understandable. How about a noise ?&nbsp;&nbsp;This cannot be understood well.That is, [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":8273,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"vkexunit_cta_each_option":"","footnotes":""},"categories":[32],"tags":[79,82,86],"class_list":["post-1898","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-category-technology","tag-technology-emc","tag-technology-ohter","tag-technology-spectrum-analyzer"],"_links":{"self":[{"href":"https:\/\/micronix-jp.com\/english\/wp-json\/wp\/v2\/posts\/1898","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/micronix-jp.com\/english\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/micronix-jp.com\/english\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/micronix-jp.com\/english\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/micronix-jp.com\/english\/wp-json\/wp\/v2\/comments?post=1898"}],"version-history":[{"count":2,"href":"https:\/\/micronix-jp.com\/english\/wp-json\/wp\/v2\/posts\/1898\/revisions"}],"predecessor-version":[{"id":10342,"href":"https:\/\/micronix-jp.com\/english\/wp-json\/wp\/v2\/posts\/1898\/revisions\/10342"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/micronix-jp.com\/english\/wp-json\/wp\/v2\/media\/8273"}],"wp:attachment":[{"href":"https:\/\/micronix-jp.com\/english\/wp-json\/wp\/v2\/media?parent=1898"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/micronix-jp.com\/english\/wp-json\/wp\/v2\/categories?post=1898"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/micronix-jp.com\/english\/wp-json\/wp\/v2\/tags?post=1898"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}