# Totem pole-How is the output

#### nepdeep

Joined Sep 14, 2011
140
I went through some posts here. But still had dillema on how the output of the following circuit would look for logic 1 and 0.. As far as I can go it seems like an inverter to me?? Help me understand please....with bit of explanation please..

#### tshuck

Joined Oct 18, 2012
3,534
I went through some posts here. But still had dillema on how the output of the following circuit would look for logic 1 and 0.. As far as I can go it seems like an inverter to me?? Help me understand please.View attachment 49622...with bit of explanation please..
When a 1 is present on the CMOS device(last stage), the NMOS pulls the output low, while the PMOS doesn't conduct. Conversely, when a 0 is present on the input, the PMOS conducts while the NMOS does not, pulling the output up to +vdd(15V).

But remember, the input is being inverted, so this device is inverting an inverted input making it a.....

#### nepdeep

Joined Sep 14, 2011
140
When a 1 is present on the CMOS device(last stage), the NMOS pulls the output low, while the PMOS doesn't conduct. Conversely, when a 0 is present on the input, the PMOS conducts while the NMOS does not, pulling the output up to +vdd(15V).

But remember, the input is being inverted, so this device is inverting an inverted input making it a.....
......buffer...inverting buffer!!

#### tshuck

Joined Oct 18, 2012
3,534
......buffer...inverting buffer!!
Well, which is it? Is the final result inverted?

#### ErnieM

Joined Apr 24, 2011
8,123
Well, which is it? Is the final result inverted?
No, the output in not inverted, but the input is. (huh?)

#### Ron H

Joined Apr 14, 2005
7,014
......buffer...inverting buffer!!
......buffer...noninverting buffer!!

#### tshuck

Joined Oct 18, 2012
3,534
......buffer...noninverting buffer!!
Ding, ding, ding! I was hoping the OP would come to this on his own...the important thing is that he knows....

#### tshuck

Joined Oct 18, 2012
3,534
No, the output in not inverted, but the input is. (huh?)
the idea was to get the OP to determine if the output was different than the input...

#### Ron H

Joined Apr 14, 2005
7,014
Ding, ding, ding! I was hoping the OP would come to this on his own...the important thing is that he knows....
Yeah, I probably should have held my tongue... ermmm, fingers.

#### nepdeep

Joined Sep 14, 2011
140
Thanks for all the brains. Now my story.

when the input (at figure) is 1 then NFET pulls Load to ground PFET doesnot conduct. so output is low
so
1 gives 0 (inverted)
when the input is 0 then NFET doesnot conduct and PFET pulls output to 15 volts. so output is high
so
0 gives 1 (inverted again!!)

Now from what ....................okey okey...okey...i was looking at the figure and typing this and suddenly saw the ball on the end of the arrow at input....that made me realise it was inverting input..okey now final conclusion hehehe
1 gives 0
0 gives 1
so 1 -> 1

0 gives 1
1 gives 0
so 0 -> 0

thank you...hope i understood ??

#### Ron H

Joined Apr 14, 2005
7,014
Thanks for all the brains. Now my story.

when the input (at figure) is 1 then NFET pulls Load to ground PFET doesnot conduct. so output is low
so
1 gives 0 (inverted)
when the input is 0 then NFET doesnot conduct and PFET pulls output to 15 volts. so output is high
so
0 gives 1 (inverted again!!)

Now from what ....................okey okey...okey...i was looking at the figure and typing this and suddenly saw the ball on the end of the arrow at input....that made me realise it was inverting input..okey now final conclusion hehehe
1 gives 0
0 gives 1
so 1 -> 1

0 gives 1
1 gives 0
so 0 -> 0

thank you...hope i understood ??
You've gotta pay attention to your balls!

#### tshuck

Joined Oct 18, 2012
3,534
You've gotta pay attention to your balls!
Oh man, how did I miss that!?