Measurements on buffer and weird output waveform

Thread Starter

luma

Joined Nov 5, 2015
50
Hi guys, here again, As you can remember from the other post I wanted to understand what's wrong in the circuit (CMOS buffer or push pull amplifier) attached.
Most of you gave me good suggestions to make it work. However before to give up with that buffer I wanted to check for real if that buffer I proposed cannot really work and how it behaves. I built the circuit by using the typical CD4007 and creating a buffer . In the attachment I wrote the number of pins and the signals.
My test consisted to bias the input of the buffer with a voltage around 5V and check what happen if I increase the input voltage of the signal. This test could give me some info about what is the caratteristc curve (vo/vin) of the buffer. However the output seems to be distorted by the buffer and I don't get why.
I attached some pictures about measurements with oscilloscope. the green line is the input, the yellow line is the output.
Anyone can explain me what happen when I increase the amplitude of the input signal? And why there is a distortion?
 

Attachments

Thread Starter

luma

Joined Nov 5, 2015
50

dl324

Joined Mar 30, 2015
9,568
What do you mean? How would you connect the bulk of the mosfet?
The bulk of a PMOS device is normally connected to the positive supply and the bulk of the NMOS device is normally connected to the negative supply. In the CD4007, those connections are already made and can't be changed.
 

Thread Starter

luma

Joined Nov 5, 2015
50
The bulk of a PMOS device is normally connected to the positive supply and the bulk of the NMOS device is normally connected to the negative supply. In the CD4007, those connections are already made and can't be changed.
Thanks for your comment, however as is shown in the schematic the bulk are connected as you said. Look better . Second : the bulks on the CD4007 available externally and not internally connected. Look better to the datasheet.
(p.s in my schematic I forgot to draw the number of the pin for the bulks but the bulk of NMOS is 7 top GND and the bulk of PMOS is 14 to VDD)
 

Thread Starter

luma

Joined Nov 5, 2015
50
PIN 14 to VDD and pin 7 to GND. Also a push pull amplifier do not provide any voltage gain .
Thank you jony for your answer can you quote, the question, otherwise i cannot understand to which question or sentence you are answering.
 

Thread Starter

luma

Joined Nov 5, 2015
50
You need to follow your own advice. In your schematic, you show the connections backwards. The bulk of the PMOS is connected to 0V and the bulk of the NMOS is connected to 10V.
Photo 29-01-16 16 22 42.jpg

AND if you see carefully also in my previous thread the bulk are connected correctly
 

bertus

Joined Apr 5, 2008
20,227
Hello,

Which connections did you use?

4007_connections.png

In the datasheet there is this given for biasing:

4007_bias.png

I have also attached the PDF that contains the shown images.

Bertus
 

Attachments

Thread Starter

luma

Joined Nov 5, 2015
50
Hello,

Which connections did you use?

View attachment 99642

In the datasheet there is this given for biasing:

View attachment 99643

I have also attached the PDF that contains the shown images.

Bertus
thank you for your answer the pin i m using are drawed in my schematic, please check there, however is the second pair of mosfet in the image you post it.
The schematic you show and suggested by the company is just for na inverter while
i built a push pull amplifier
 

bertus

Joined Apr 5, 2008
20,227
Hello,

Why do you post the pictures on its side?
I will NOT turn my monitor to view the image !
It can easily be corrected using any kind of paint program:

Luma_inverter.jpg

Bertus
 
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