{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

bjtbias - c Copyright 2008 W Marshall Leach Jr Professor...

Info icon This preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
c ° Copyright 2008. W. Marshall Leach, Jr., Professor, Georgia Institute of Technology, School of Electrical and Computer Engineering. The BJT Bias Equation Basic Bias Equation (a) Look out of the 3 terminals of the BJT and make Thévenin equivalent circuits as shown in Fig. 1. Figure 1: Basic bias circuit. (b) Write a loop equation for the base-emitter loop. V BB V EE = I B R BB + V BE + I E R EE (c) Use the relation I C = βI B = αI E to express I B and I E as functions of the current desired. Let I C be the current. V BB V EE = I C β R BB + V BE + I C α R EE (d) Solve for I C . I C = V BB V EE V BE R BB β + R EE α An “educated guess” of the value of V BE must be made to evaluate this. Typical values are 0 . 7 V for IC transistors, 0 . 6 0 . 65 V for low-power discrete transistors, and 0 . 5 0 . 6 V for higher-power discrete transistors. (e) Check for the active mode. For the active mode, V CB > 0 . V CB = V C V B = ( V CC I C R CC ) ( V BB I B R BB ) or = ( V CC I C R CC ) ( V EE + I E R EE + V BE ) Example 1 V BB = V + R 2 + V R 1 R
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern