{"id":7829,"date":"2023-03-04T10:32:17","date_gmt":"2023-03-04T10:32:17","guid":{"rendered":"https:\/\/www.goodacademic.com\/blog\/questions\/discussion-reply-high-filter-pass\/"},"modified":"2023-03-04T10:32:17","modified_gmt":"2023-03-04T10:32:17","slug":"discussion-reply-high-filter-pass","status":"publish","type":"questions","link":"https:\/\/www.goodacademic.com\/blog\/questions\/discussion-reply-high-filter-pass\/","title":{"rendered":"Discussion Reply: High Filter pass"},"content":{"rendered":"<p>&nbsp;<\/p>\n<p>High-pass filters are circuits that allow relatively high frequency &nbsp;signals to be transmitted through the input to the output while &nbsp;attenuating relatively low frequency signals. Conversely, low-pass &nbsp;filters are circuits that allow relatively low frequency signals to be &nbsp;transmitted through the input to the output while attenuating relatively &nbsp;high frequency signals.&nbsp; Common-emitter BJTs have both characteristics &nbsp;of low pass and high pass filters.\n<\/p>\n<p>Coupling capacitors and bypass &nbsp;capacitors (external capacitors) do affect input and output &nbsp;characteristics of amplifier circuits.&nbsp; For example, both voltage gain &nbsp;and phase shift of amplifier circuits can be affected by these &nbsp;capacitors.&nbsp; We can see from the equation for capacitive reactance Xc = &nbsp;1\/(2 pi * f * c) that frequency is inversely proportional to capacitive reactance.&nbsp; &nbsp;Therefore, low frequencies cause high capacitive reactance values and &nbsp;vice versa.&nbsp; High capacitive reactance cause less current to flow and &nbsp;therefore reduce voltage gain (i.e. the voltage gain of a common- &nbsp;collector amplifier).&nbsp; In the common-collector amplifier there is an &nbsp;ideal phase shift of 180\u00b0, which is a direct result of the coupling &nbsp;capacitors in the circuit.&nbsp; Also, the bypass capacitor in a CE &nbsp;configuration blocks DC but allows AC to pass and thereby further &nbsp;stabilizing the circuit.&nbsp; Internal transistor capacitance has an adverse &nbsp;effect as input signal frequencies increase causing less than ideal &nbsp;characteristics such as phase shift and reduction in voltage gain.<\/p>\n<p>The &nbsp;bandwidth is the range of frequencies in which an amplifier is designed &nbsp;to operate. This range falls between the dominant upper and lower &nbsp;critical frequencies. The following equation expresses this bandwidth:&nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;<br \/>\nBW =f&#8217;cu(dom)-f&#8217;cl(dom)<\/p>\n<ul>\n<li>Having &nbsp;two cut off frequencies that are the same in an amplifier causes &nbsp;different outcomes depending on whether or not the critical frequencies &nbsp;are lower or upper critical frequencies. If they are dominant lower &nbsp;critical frequencies, the overall dominant lower critical frequency is &nbsp;increased by a factor of 1\/ sqrt[(2^1\/n) -1] as shown by the equation &nbsp;f&#8217;cl(dom=fcl(dom)\/sqrt[(2^1\/n) -1], where n is equal to the number of &nbsp;stages of the amplifier. If they are dominant upper critical &nbsp;frequencies. the overall dominant upper critical frequency is reduced by &nbsp;a factor of sqrt[(2^1\/n) -1], as shown by the equation&nbsp; &nbsp;f&#8217;cu(dom)=fcu(dom)sqrt[(2^1\/n) -1].<\/li>\n<\/ul>\n<p>References<\/p>\n<p>Floyd, &nbsp;Thomas L. Electronic Devices (Conventional Current Version). Available &nbsp;from: ECPI, (10th Edition). Pearson Education (US), 2017.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>&nbsp; High-pass filters are circuits that allow relatively high frequency &nbsp;signals to be transmitted through the input to the output while &nbsp;attenuating relatively low frequency signals. Conversely, low-pass &nbsp;filters are circuits that allow relatively low frequency signals to be &nbsp;transmitted through the input to the output while attenuating relatively &nbsp;high frequency signals.&nbsp; Common-emitter BJTs have [&hellip;]<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"closed","template":"","meta":[],"disciplines":[221],"paper_types":[],"tagged":[],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/www.goodacademic.com\/blog\/wp-json\/wp\/v2\/questions\/7829"}],"collection":[{"href":"https:\/\/www.goodacademic.com\/blog\/wp-json\/wp\/v2\/questions"}],"about":[{"href":"https:\/\/www.goodacademic.com\/blog\/wp-json\/wp\/v2\/types\/questions"}],"author":[{"embeddable":true,"href":"https:\/\/www.goodacademic.com\/blog\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/www.goodacademic.com\/blog\/wp-json\/wp\/v2\/comments?post=7829"}],"version-history":[{"count":0,"href":"https:\/\/www.goodacademic.com\/blog\/wp-json\/wp\/v2\/questions\/7829\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.goodacademic.com\/blog\/wp-json\/wp\/v2\/media?parent=7829"}],"wp:term":[{"taxonomy":"disciplines","embeddable":true,"href":"https:\/\/www.goodacademic.com\/blog\/wp-json\/wp\/v2\/disciplines?post=7829"},{"taxonomy":"paper_types","embeddable":true,"href":"https:\/\/www.goodacademic.com\/blog\/wp-json\/wp\/v2\/paper_types?post=7829"},{"taxonomy":"tagged","embeddable":true,"href":"https:\/\/www.goodacademic.com\/blog\/wp-json\/wp\/v2\/tagged?post=7829"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}