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True Table

Screenshot 2020-10-19 at 20.22.09.png

 Can someone help with true table for this schematic please?

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Hi adi80,

 

 

This is a CMOS NAND gate and the truth table is below:

 

 A     B     Q

High  High  Low

High  Low   High

Low   High  High

Low   Low   High

 

The detailed states of the MOSFETs are below:

 

A=High, B=High

M1=OFF, M2=OFF, M3=ON,  M4=ON

Q=Low

A=High, B=Low

M1=ON,  M2=OFF, M3=ON,  M4=OFF

Q=High

A=Low,  B=High

M1=OFF, M2=ON,  M3=OFF, M4=ON

Q=High

A=Low,  B=Low

M1=ON,  M2=ON,  M3=OFF, M4=OFF

Q=High

 

Be careful when analyzing these states, note that A drives M2 and M3 while B drives M1 and M4. The table can be made more organized if the circuit is rewired (or component designation interchanged), for example with M1 being driven by A and M3 being driven by B.

 

If you will build this circuit I suggest that you replace the output variable Q with other name such as Y. In digital design, Q is generally used for latch/flip-flop (and derived functions) output.

 

 

Best regards,

G. Goodwin

 

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Thank you very much.
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