{"id":2962,"date":"2024-08-25T22:02:34","date_gmt":"2024-08-25T22:02:34","guid":{"rendered":"https:\/\/workhouse.sweetdishy.com\/?p=2962"},"modified":"2024-08-25T22:02:35","modified_gmt":"2024-08-25T22:02:35","slug":"the-transistor-as-a-switch","status":"publish","type":"post","link":"https:\/\/workhouse.sweetdishy.com\/index.php\/2024\/08\/25\/the-transistor-as-a-switch\/","title":{"rendered":"The Transistor as a Switch"},"content":{"rendered":"\n

To illustrate the application of a transistor as a switch, first consider a simple circuit comprising a resistor and a real switch (Figure 10.8).<\/p>\n\n\n\n

\"image\"\/<\/figure>\n\n\n\n

Figure 10.8<\/strong> Resistor-switch circuit (a) Circuit; (b) Waveform<\/p>\n\n\n\n

The labels VDD<\/sub><\/em> and VSS<\/sub><\/em> are commonly used in circuits employing MOSFETs. At this point we have little interest in their actual values and, for the purpose of these examples, need only assume that VDD<\/sub><\/em> is more positive than VSS<\/sub><\/em>.<\/p>\n\n\n\n

When the switch is OPEN (OFF), VOUT<\/sub><\/em> is connected via the resistor to VDD<\/sub><\/em>; when the switch is CLOSED (ON), VOUT<\/sub><\/em> is connected via the switch directly to VSS<\/sub><\/em>. In this latter case, VOUT<\/sub><\/em> takes the value VSS<\/sub><\/em> because, like people, electricity takes the path of least resistance, and the resistance to VSS<\/sub><\/em> through the closed switch is far less than the resistance to VDD<\/sub><\/em> through the resistor. The waveforms in the illustration above show a delay between the switch operating and VOUT<\/sub><\/em> responding. Although this delay is extremely small, it is important to note that there will always be some element of delay in any physical system.<\/p>\n\n\n\n

Now consider the case where the switch is replaced with an NMOS transistor whose control input can be switched between\u00a0VDD<\/sub><\/em>\u00a0and\u00a0VSS<\/sub><\/em>\u00a0(Figure 10.9).<\/p>\n\n\n\n

\"image\"\/<\/figure>\n\n\n\n

Figure 10.9<\/strong> Resistor-NMOS transistor circuit (a) Circuit; (b) Waveform<\/p>\n\n\n\n

When the control input to an NMOS transistor is connected to VSS<\/sub><\/em>, the transistor is turned OFF and acts like an OPEN switch; when the control input is connected to VDD<\/sub><\/em>, the transistor is turned ON and acts like a closed switch. Thus, the transistor functions in a similar manner to the switch. However, a switch is controlled by hand and can only be operated a few times a second, but a transistor\u2019s control input can be driven by other transistors, allowing it to be operated millions of times a second.<\/p>\n","protected":false},"excerpt":{"rendered":"

To illustrate the application of a transistor as a switch, first consider a simple circuit comprising a resistor and a real switch (Figure 10.8). Figure 10.8 Resistor-switch circuit (a) Circuit; (b) Waveform The labels VDD and VSS are commonly used in circuits employing MOSFETs. At this point we have little interest in their actual values and, for the purpose of […]<\/p>\n","protected":false},"author":1,"featured_media":2487,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[417],"tags":[],"class_list":["post-2962","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-digital-electronics"],"jetpack_featured_media_url":"https:\/\/workhouse.sweetdishy.com\/wp-content\/uploads\/2024\/08\/smartphone_5337695.png","_links":{"self":[{"href":"https:\/\/workhouse.sweetdishy.com\/index.php\/wp-json\/wp\/v2\/posts\/2962","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/workhouse.sweetdishy.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/workhouse.sweetdishy.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/workhouse.sweetdishy.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/workhouse.sweetdishy.com\/index.php\/wp-json\/wp\/v2\/comments?post=2962"}],"version-history":[{"count":1,"href":"https:\/\/workhouse.sweetdishy.com\/index.php\/wp-json\/wp\/v2\/posts\/2962\/revisions"}],"predecessor-version":[{"id":2963,"href":"https:\/\/workhouse.sweetdishy.com\/index.php\/wp-json\/wp\/v2\/posts\/2962\/revisions\/2963"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/workhouse.sweetdishy.com\/index.php\/wp-json\/wp\/v2\/media\/2487"}],"wp:attachment":[{"href":"https:\/\/workhouse.sweetdishy.com\/index.php\/wp-json\/wp\/v2\/media?parent=2962"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/workhouse.sweetdishy.com\/index.php\/wp-json\/wp\/v2\/categories?post=2962"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/workhouse.sweetdishy.com\/index.php\/wp-json\/wp\/v2\/tags?post=2962"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}