The circuit employs pass transistor logic. All NMOS transistors a
The circuit employs pass transistor logic. All NMOS transistors are identical with threshold voltage of 1 V. Ignoring the body effect-the output voltage at P, Q, R are
A. 4V, 4V, 4V
B. 4V, 3V, 2V
C. 4V, 3V, 3V
D. 5V, 4V, 3V
Please scroll down to see the correct answer and solution guide.
Right Answer is: B
SOLUTION
Concept:
For the pass transistor logic
\({{V}_{s}}=\left\{ \begin{matrix} {{V}_{D}} & {{V}_{D}}<{{V}_{G}}-{{V}_{T}} \\ {{V}_{G}}-{{V}_{T}} & {{V}_{D}}\ge {{V}_{G}}-{{V}_{T}} \\ \end{matrix} \right.\)
Application:
For the first transistor
VD = 5 V
VG - VT = 5 – 1 = 4 V
VD > VG - VT
VS = VG - VT
VP = VD2 = VS - VT = 4 V
Case 2:
For 2nd pass transistor logic
VD = 4 V
VG - VT = 3 V
VD > VG - VT
VQ = VD3 = 3 V
Case 3:
For third pass transistor logic
VD = 3 V
VG - VT = 3 – 1 = 2 V
VD > VG – VT
VR = 2 V