Multiple choice

For the circuit shown in the following figure, transistor M1 and M2 are identical NMOS transistors. Assume the M2 is in saturation and the output is unloaded.

  1. Ix = Ibias + Is

  2. Ix = Ibias

  3. Ix = Ibias - $\bigg(V_{DD} - \frac{V_{out}}{R_E}\bigg)$
  4. Ix = Ibias - Is

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$\text{By current mirror} \\ I_x = \frac{\Big(\frac{W}{L}\Big)2}{\Big(\frac{W}{L}\Big)_1}I{bias} \\ \text{Since MOSFETs are identical,} \\ \text{Thus} \hspace{1cm} \Big(\frac{W}{L}\Big)2 = \Big(\frac{W}{L}\Big)_2 \\ \text{Hence} \hspace{1cm} I_x = I{bias}$