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Re: AD8237 Gain/Bandwidth problem

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Hey Emman,

 

Yea this may have been a little hard to follow.

 

My circuit:

-Are you getting your input signal from a wheatstone bridge with an excitation voltage of 3.3 V?

yes

 

-Does the inputs of the AD8237 are AC coupled?

yes

 

-If yes, are you planning to apply bias on pin 2 and pin 3?

yes

 

-If yes, are you planning to apply bias on pin 2 and pin 3?

yes.  I have two 100k pull-downs

 

-What is the supply voltage of the AD8237?

3.3Vdc

 

-What is your expected differential input voltage ( Vin+ - Vin-)?

For the main sensor I'm targeting for this application -> 30mV

 

Vref is tied to GND

 

The gain is 100 max.

 

I'll be honest...I"m not really familiar with those plots.  I'm a digital guy so I'm not great in the analog world.  Would it be easier if I sent you a pdf of my whole filter/gain/amp schematic that I'm planning on implementing in my product?  I will be using one of these circuits PER channel on my data acquisition device.  If you give me a contact ponit (email) I can send you the pdf with all the detail so you can check it out.  I just don't want to post up the design on here.

 

As for the circuit it is differential, but I can't recreate the sensor output so I was trying to tie the neg. pin to GND and put a signal on the pos. pin just to get a ROUGH idea of whether it works or the design is just totally wrong.  So far it looks great.  I'll be honest.  I've got a 3 stage circuit and I tested out the whole thing this morning and my cut-off frequency is -3db down, signal looks clean.  I'm very excited!

 

But yes, long story short I was trying to lab test a differential amp in a single ended "way".


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