1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Common-Source JFET Amplifier problem

  1. Nov 6, 2012 #1
    1. The problem statement, all variables and given/known data
    For the prelab assume that the JFET has the following typical specifications:
    IDSS = 10.0 mA
    VGS(OFF) = -3.5 V
    rds = 50.0 kW
    1. Complete the design for the bias circuit in Figure 1 given that the desired Q-point for the
    JFET is ID = 2.0 mA and VDS = 6.0 V by following these steps:
    (a) Calculate the following values for this JFET:
    VGS = _____________ gm = _____________

    15x7tah.png

    2. Relevant equations

    gm = 2 * Id / Vgs - Vth

    3. The attempt at a solution

    Is it safe to assume that VGS(off) is the pinch off voltage for the transfer plot?
    What is rds?
     
  2. jcsd
  3. Nov 7, 2012 #2

    NascentOxygen

    User Avatar

    Staff: Mentor

  4. Nov 8, 2012 #3
    A transistor amplifier is operated in saturation, so rds wil not be involved in any load line. It may, however, help to determine some unknown transistor parameter. As mentioned, rds is the approximate resistance between the drain and source when the transistor is in triode with vds small.

    Edit: And yes, that will be the pinch off voltage.
     
    Last edited: Nov 8, 2012
  5. Nov 8, 2012 #4

    NascentOxygen

    User Avatar

    Staff: Mentor

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Common-Source JFET Amplifier problem
  1. JFET Amplifier (Replies: 2)

  2. Common Base Amplifier (Replies: 2)

Loading...