Dear Team,

I am designing an instrumentation amplifier using INA333 .The schematic is given below.
The spice model is available in the above link.The name of spice model is given below.


For testing purpose I provided an I/P signal of 10mV and the set gain is 40
The expected 400mV ,but I am getting 95mV.
May I know where I went wrong.

 

I think you are exceeding the common-mode range limits (below).
Note that the minimum input voltage is slightly above the negative rail voltage (in your case that's 0V), and you are starting from 0V on both inputs.
Trying adding a small bias voltage to both inputs (e.g. +0.5V).

 

You are correct. I am exceeding the common-mode range limits .
As you suggested added a small bias voltage to both inputs .
Now it is working fine.
Thank you.

 

Aside from exceeding the input limits, also you are not powering the instrument amp correctly. Most inst amps require a bipolar supply, both V+ AND V-, which would be a NEGATIVE voltage. Then Vref could be the common. Read the data sheet about the required supply voltages. AND look at the typical application circuit that is shown.
An instrument amp must be powered correctly to get anything close to correct operation.

 

you are not powering the instrument amp correctly

Really?

Read the data sheet about the required supply voltages.

Did you read the data sheet? (below from pg. 17)
It's a RR out device that can operate with a single supply, with inputs to within 0.1V of the supply rails.

 

OK, No, I did not read the data sheet for that particular IC device. BUT I have used quite a dew instrument amplifiers, and they all required a bipolar supply. AND, for this device, even, the supply voltage does impose limits on the output voltage. Raising the supply voltage will raise the allowable common mode voltage, and using a bi-polar supply will solve the rest of the problems.

 

using a bi-polar supply will solve the rest of the problems.

What problems?
He stated the circuit was working with the suggested small increase in the common-mode input voltage.
He has no other problems that we know of.