Multiple choice

The drain current of MOSFET in saturation is given by ID = K (VGS-VT) where K is constant. The magnitude of the transconductance gm is

  1. $\dfrac{K(V_{GS}- V_T)^2}{V_{DS}}$

  2. 2K (VGS - VT)
  3. $\dfrac{I_d}{V_{GS} - V_{DS}}$
  4. $\dfrac{K (V_{GS} - V_T)^2 }{V_{GS}}$
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B Correct answer
Explanation

$g_m = \dfrac{\partial I_P}{\partial V_{GS} } = \dfrac{\partial}{\partial V_{GS} } K (V_{GS} - V_T)^2 = 2K (V_{GS} - V_T)$

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