Topic: Digital Electronics
Which logical function is implemented by following Transmission Gate based circuit?
(The circuit displays a standard CMOS complex logic gate structure with a pull-up PMOS network and a pull-down NMOS network taking inputs A, B, C, and D).
- A. $Y=(A(B+C)+D)$
- B. $Y=A(B+C)+D$
- C. $Y=(A+BC)D$
- D. $Y=\overline{((A+BC)D)}$
Answer: D. $Y=\overline{((A+BC)D)}$
Explanation: The image represents a static CMOS logic gate, not a transmission gate. Observing the pull-down NMOS network: transistor D is in series with a group composed of A in parallel with the series combination of B and C. This forms the logic $D(A+BC)$. Because of the inherent inversion in static CMOS gates, the output is $Y = \overline{D(A+BC)} = \overline{((A+BC)D)}$.