Chapter 4
Q. 4.SP.2
For the MOSFET amplifier of Example 4.5, let V_{GSQ} = 6.90 \text{V}. Calculate I_{DQ} from the analog of (4.2) developed in Section 4.8.
i_{D} = I_{DSS} \left(1 + \frac{v_{GS}}{V_{p0}} \right)^2 (4.2)
Step-by-Step
Verified Solution
From the drain characteristics of Fig. 4-9(b), we see that V_T = 4 \text{V} and that I_{D\text{on}} = 5 \text{mA} at V_{GSon} = 8 \text{V}. Thus,
I_{DQ} = I_{D\text{on}} \left(1 – \frac{V_{GSQ}}{V_T} \right)^2 = 5 × 10^{-3} \left(1 – \frac{6.90}{4} \right)^2 = 2.63 \text{mA}(Compare Example 4.5.)
