For an ideal symmetric CMOS inverter operating from a 10 V supply, what is the…

Concept

The switching threshold of an ideal symmetric CMOS inverter is the input voltage at which the pull-up and pull-down networks have equal drive and the output is at the transition point.

With matched effective strengths and complementary threshold magnitudes, this point lies midway between ground and the supply: VM = VDD / 2.

Application

1. Take the supply voltage as VDD = 10 V.

2. Apply the symmetric-inverter relation: VM = VDD / 2.

3. Therefore, VM = 10 V / 2 = 5 V.

Cross-check

The transition point must divide the 0 V to 10 V input range into equal halves; 5 V is exactly the midpoint.

Hence, the switching (transition) input voltage is 5 V.