Deprecated: Assigning the return value of new by reference is deprecated in /home/freehos1/public_html/blinki/wp-settings.php on line 520

Deprecated: Assigning the return value of new by reference is deprecated in /home/freehos1/public_html/blinki/wp-settings.php on line 535

Deprecated: Assigning the return value of new by reference is deprecated in /home/freehos1/public_html/blinki/wp-settings.php on line 542

Deprecated: Assigning the return value of new by reference is deprecated in /home/freehos1/public_html/blinki/wp-settings.php on line 578

Deprecated: Function set_magic_quotes_runtime() is deprecated in /home/freehos1/public_html/blinki/wp-settings.php on line 18

Strict Standards: Declaration of Walker_Page::start_lvl() should be compatible with Walker::start_lvl(&$output) in /home/freehos1/public_html/blinki/wp-includes/classes.php on line 1199

Strict Standards: Declaration of Walker_Page::end_lvl() should be compatible with Walker::end_lvl(&$output) in /home/freehos1/public_html/blinki/wp-includes/classes.php on line 1199

Strict Standards: Declaration of Walker_Page::start_el() should be compatible with Walker::start_el(&$output) in /home/freehos1/public_html/blinki/wp-includes/classes.php on line 1199

Strict Standards: Declaration of Walker_Page::end_el() should be compatible with Walker::end_el(&$output) in /home/freehos1/public_html/blinki/wp-includes/classes.php on line 1199

Strict Standards: Declaration of Walker_PageDropdown::start_el() should be compatible with Walker::start_el(&$output) in /home/freehos1/public_html/blinki/wp-includes/classes.php on line 1244

Strict Standards: Declaration of Walker_Category::start_lvl() should be compatible with Walker::start_lvl(&$output) in /home/freehos1/public_html/blinki/wp-includes/classes.php on line 1391

Strict Standards: Declaration of Walker_Category::end_lvl() should be compatible with Walker::end_lvl(&$output) in /home/freehos1/public_html/blinki/wp-includes/classes.php on line 1391

Strict Standards: Declaration of Walker_Category::start_el() should be compatible with Walker::start_el(&$output) in /home/freehos1/public_html/blinki/wp-includes/classes.php on line 1391

Strict Standards: Declaration of Walker_Category::end_el() should be compatible with Walker::end_el(&$output) in /home/freehos1/public_html/blinki/wp-includes/classes.php on line 1391

Strict Standards: Declaration of Walker_CategoryDropdown::start_el() should be compatible with Walker::start_el(&$output) in /home/freehos1/public_html/blinki/wp-includes/classes.php on line 1442

Strict Standards: Redefining already defined constructor for class wpdb in /home/freehos1/public_html/blinki/wp-includes/wp-db.php on line 306

Strict Standards: Redefining already defined constructor for class WP_Object_Cache in /home/freehos1/public_html/blinki/wp-includes/cache.php on line 431

Strict Standards: Declaration of Walker_Comment::start_lvl() should be compatible with Walker::start_lvl(&$output) in /home/freehos1/public_html/blinki/wp-includes/comment-template.php on line 0

Strict Standards: Declaration of Walker_Comment::end_lvl() should be compatible with Walker::end_lvl(&$output) in /home/freehos1/public_html/blinki/wp-includes/comment-template.php on line 0

Strict Standards: Declaration of Walker_Comment::start_el() should be compatible with Walker::start_el(&$output) in /home/freehos1/public_html/blinki/wp-includes/comment-template.php on line 0

Strict Standards: Declaration of Walker_Comment::end_el() should be compatible with Walker::end_el(&$output) in /home/freehos1/public_html/blinki/wp-includes/comment-template.php on line 0

Strict Standards: Redefining already defined constructor for class WP_Dependencies in /home/freehos1/public_html/blinki/wp-includes/class.wp-dependencies.php on line 31

Strict Standards: Redefining already defined constructor for class WP_Http in /home/freehos1/public_html/blinki/wp-includes/http.php on line 61

Strict Standards: Redefining already defined constructor for class SimpleGoogleSitemap in /home/freehos1/public_html/blinki/wp-content/plugins/simple-google-sitemap/simple-google-sitemap.php on line 46
Transmission Gates:How it operates | Blinki Blog - 2 GB FREE
Home > Digital electronics > Transmission Gates:How it operates

Transmission Gates:How it operates

October 12th, 2010 admin Leave a comment Go to comments

A transmission gate is an electronic element. It is a good non-mechanical relay, built with CMOS technology. It is sometimes known as an analog gate, analogue switch or electronic relay depending on its use. It is made by the parallel combination of an nMOS and a pMOS transistor with the input at the gate of one transistor being complementary to the input at the gate    of the other.

tgate1

Operation:

A current can flow through this element in either direction. Depending on whether or not there is a voltage on the gate, the connection between the input and output is either low-resistance or high-resistance, respectively. Ron = 100 ohm and Roff > 5 megohm.

tgate2The operation can also be understood this way: when the gate input to the nMOS transistor is ‘0′, and the complementary ‘1′ is gate input to the pMOS, both are turned off. However when gate input to the nMOS is ‘1′ and its complementary ‘0′ is the gate input to the pMOS, both are turned on and passes any signal ‘1′ or ‘0′ equally well without degradation. The use of transmission gates eliminates the undesirable threshold voltage effects which give rise to loss of logic levels in pass-transistors.

The above logic was invented as a solution to problems of earlier CMOS logics. It enables certain logic functions to be implemented with fewer transistors than possible using other CMOS logic.

This logic can be used to design multiplexers.

Design

It would seem that a transmission gate could be constructed using simply a single pMOS or nMOS transistor. If only an individual nMOS transistor were to be used, and there was a high voltage out the OUT and a low voltage on the IN and we are trying to transmit the zero to the OUT, then the nMOS will drain some of the voltage but not all of it leaving the OUT somewhere in the ‘no mans’ voltage region of digital circuits. Adding the pMOS gate in parallel allows all the voltage to drain after the nMOS shuts off before all the voltage is drained. This also solves the problem when transmitting a high voltage to OUT.

  1. No comments yet.
  1. No trackbacks yet.
You must be logged in to post a comment.