CMOS adder circuit

Thread Starter


Joined Apr 8, 2008
hello everyone,
Im doing Comparison of Characteristic in some CMOS adder circuit. I've choose Ripple Carry Adder, Carry Look ahead adder and Manchester Adder. Is it a wise choice to?
1. I would to know how can i connect 1 bit full adder into 4 bit to make it 4 bit ripple carry adder. I have try it when i connect the Cout into the second fulladder Cin. Do I should connect every Cin with Cout in the previous fulladder? The circuit become very messy. And it cannot run. Im using Pspice Full version. Attached is the full adder circuit that i have tried. Please trouble shoot the circuit.

2. I've only found Cout circuit for both carry lookahead adder and Manchester adder. Where can i get the full transistor level circuit for the two types of adder?

I really need some help. I need to submit my project soon.
Thank you.



Joined Feb 24, 2006
We are mostly hobbyists and experimenters. Design at the CMOS transistor level is a bit beyond what we have the capital to spend on EDA tools or a semiconductor fab. There are probably better forums to try for this sort of help.