Question

The transistors and shown in the figure have a threshold voltage of 1 volt. The device parameters $K_1$ and $K_2$ of $T_1$ and $T_2$ are $36\mu A/v^2$ and $9\mu A/V^2$ respectively. The output voltage $V_0$ is nearly

• A. 4 V
• B. 3 V
• C. 1 V
• D. 2 V

Answer 1

The correct option is B 3 V

Since both the transistors are in saturation region, thus

$K_1(V_{GS1}-V_T{)}^2=K_2(V_{GS2}-V_T{)}^2$

$K_1(5-V_0-1{)}^2=K_2(V_0-1{)}^2$

$\frac{4-V_0}{V_0-1}=\sqrt{\frac{K_2}{K_1}}=\sqrt{\frac{9}{36}}=\sqrt{\frac{1}{4}}=\frac{1}{2}$

$8-2V_0=V_0-1$

$9=3V_0$

$V_0=3volts$