Can my dynamic design be correct given it has no PMOS transistor?

Thread Starter


Joined Jul 21, 2018
I am working on an assignment and I am very confused with it.

As far as I understand, a dynamic design will charge/discharge a load capacitor on the pre-charge phase (clock = LOW) and follow a desired design logic on the evaluation phase (clock = HIGH). This is achieved with the use of a PMOS transistor to read clock signal in pre-charge phase and NMOS transistors for the evaluation phase.

However, on my assignment, the clock is also part of the logic, and therefore the dynamic design is not as straight-forward as all the examples I have found and understood, where there we have a PMOS for the pre-charge phase and an NMOS system for the evaluation phase.

Here is the question:

I devised that the equation I am working with is Y = (A⊕B)⊕C

With the following truth table:

From the truth table above I singled out all the combinations that leads to Y = 0, to end with the following function (using ! to represent NOT):

!Y = !C(!A!B + AB) + C(!AB + A!B)

This will be the NMOS part of the design, or the evaluation part.

I then drew the schematic as follows:

However, I find myself questioning if this is the right design, given the lack of any PMOS transistors.

Please, any advise or resources would be great!