3212 sjtu j chen 12 the cs amplifier is the best

This preview shows page 12 - 20 out of 33 pages.

3/2/12 SJTU J. Chen 12 The CS amplifier is the best suited for obtaining the bu lk of gain required in an amplifier. Including resistance RS in the source lead of CS ampli fier provides a number of improvements in its perform ance. The low input resistance of CG amplifier makes it usef ul only in specific application. It has excellent high-freq uency response. It can be used as a current buffer. Source follower finds application as a voltage buffer a nd as the output stage in a multistage amplifier. Summary and comparisons
Image of page 12

Subscribe to view the full document.

3/2/12 SJTU J. Chen 13 Internal capacitances The gate capacitive effect § Triode region § Saturation region § Cutoff region § Overlap capacitance The junction capacitances § Source-body depletion-layer capacitance § drain-body depletion-layer capacitance High-frequency model The internal capacitance and high-frequency mo del
Image of page 13
3/2/12 SJTU J. Chen 14 MOSFET operates at triode region MOSFET operates at saturation region MOSFET operates at cutoff region The gate capacitive effect ox gd gs WLC C C 2 1 = = = = 0 3 2 gd ox gs C WLC C = = = ox gb gd gs WLC C C C 0
Image of page 14

Subscribe to view the full document.

3/2/12 SJTU J. Chen 15 Overlap capacitance results from the fact that the source a nd drain diffusions extend slightly under the gate oxide. The expression for overlap capacitance Typical value Overlap capacitance l This additional component should be added to Cgs and Cgd in all preceding formulas ox ov ov C WL C = L L ov 1 . 0 05 . 0 - =
Image of page 15
3/2/12 SJTU J. Chen 16 Source-body depletion-layer capacitance drain-body depletion-layer capacitance The junction capacitances o SB sb sb V V C C 1 0 = o DB db db V V C C 1 0 =
Image of page 16

Subscribe to view the full document.

3/2/12 SJTU J. Chen 17 High-frequency model
Image of page 17
3/2/12 SJTU J. Chen 18 The equivalent circuit model with Cdb neglected (to simplify analysis) High-frequency model The equivalent circuit for the case in which the source is connected to the substrate (body)
Image of page 18

Subscribe to view the full document.

3/2/12 SJTU J. Chen
Image of page 19
Image of page 20
You've reached the end of this preview.
  • Fall '10
  • ChengJianping
  • Transistor, Bipolar junction transistor, Buffer amplifier, Field-effect transistor, J. Chen

{[ 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