VGS (V) 0 -1 -2 -3 -4 ID (mA) 12 6.75 3.0 0.75 0 Plot: Parabolic curve from (0 V, 12 mA) to (–4 V, 0 mA).

$I_{DSS}$ is the drain current when $V_{GS} = 0$ V. From the table, when $V_{GS} = 0$ V, $I_D = 12$ mA.
So, $I_{DSS} = 12 \text{ mA}$.

$V_P$ (pinch-off voltage or $V_{GS(off)}$) is the gate-source voltage at which $I_D = 0$ mA. From the table, when $V_{GS} = -4$ V, $I_D = 0$ mA.
So, $V_P = -4 \text{ V}$.

• For $V_{GS} = -1$ V:

$$I_D = 12 \text{ mA} \left(1 + \frac{-1}{4}\right)^2 = 12 \text{ mA} \left(0.75\right)^2 = 12 \text{ mA} \times 0.5625 = 6.75 \text{ mA}$$

• For $V_{GS} = -2$ V:

$$I_D = 12 \text{ mA} \left(1 + \frac{-2}{4}\right)^2 = 12 \text{ mA} \left(0.5\right)^2 = 12 \text{ mA} \times 0.25 = 3.0 \text{ mA}$$

• For $V_{GS} = -3$ V:

$$I_D = 12 \text{ mA} \left(1 + \frac{-3}{4}\right)^2 = 12 \text{ mA} \left(0.25\right)^2 = 12 \text{ mA} \times 0.0625 = 0.75 \text{ mA}$$

All calculated values match the provided data.

The equation $I_D = I_{DSS} \left(1 - \frac{V_{GS}}{V_P}\right)^2$ describes a parabolic curve. The data points confirm this parabolic relationship, starting from $(V_{GS}, I_D) = (0 \text{ V}, 12 \text{ mA})$ and ending at $(-4 \text{ V}, 0 \text{ mA})$.

The plot description is consistent with the provided data and the characteristics of a JFET/depletion-mode MOSFET.
The key parameters are:

• Drain-Source Saturation Current ($I_{DSS}$): $\boxed{\text{12 mA}}$
• Pinch-off Voltage ($V_P$ or $V_{GS(off)}$): $\boxed{\text{-4 V}}$