Why Does My CMOS Circuit Fail to Pull Up?

[jisbon]

Homework Statement

Construct a CMOS circuit from (A'+B.C)'

Relevant Equations

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As attached below, I have drawn the step down and up diagram. However comparing to the answer, it seems to be way too off. Any idea why?

Answer:

Is there something wrong with my step down/step up circuit?

 

[phyzguy]

How does your output ever pull up?

 

[jisbon]

How does your output ever pull up?

Hi there, I'm not sure what you are specifying about as I am pretty new to this. I watched this video and learned from him though:
He stated that for pull-down, I should just simply draw the equation out without the inverse, which is what I have done

 

[phyzguy]

The point is that the output has to be able to pull up (high) and be able to pull down (low). Look at the correct answer. The output pulls down through the NMOS transistors, and pulls up through the PMOS transistors (the ones with the circles). In your circuit, there is nothing to pull the output up. Try studying some simpler CMOS circuits - inverters, NAND gates, NOR gates, and try to understand how they work.