Thank you for simulating it.

I am supplying 5Vpp, 500kHz signal to the input of the in-amp, power rails of 0 to 8V (It is the single supply minimum operating range) and I am using the in-amp as a unity gain amplifier. I am giving a reference signal of 4V since I want to center my output at mid supply.
My goal is to achieve the output signal that is similar to the input signal in terms of amplitude (eg. with 5Vpp at the input, I want to achieve 5Vpp at the output).

I am not sure if I have to provide a DC offset of 4V at the input as well or I have center it at the baseline of 0V

 

hi,
Run this sim.
Post your plot.
E

 

Hi,

Yes for dual supply the IC works as I want it to, but I wanted to implement the single supply for my application with a mid-supply DC offset at the output.

 

Hi,
OK. I will post later.
E

 

Thank you for simulating it.

I am supplying 5Vpp, 500kHz signal to the input of the in-amp, power rails of 0 to 8V (It is the single supply minimum operating range) and I am using the in-amp as a unity gain amplifier. I am giving a reference signal of 4V since I want to center my output at mid supply.
My goal is to achieve the output signal that is similar to the input signal in terms of amplitude (eg. with 5Vpp at the input, I want to achieve 5Vpp at the output).

I am not sure if I have to provide a DC offset of 4V at the input as well or I have center it at the baseline of 0V

Does anyone else know how to achieve this?

 

I already told you how to do that!

What I have suggested is called a “virtual ground”, and it allows you to use signals referenced to ground that go both positive and negative. It is a way to get the advantage of dual supplies with a single supply

 

Does anyone else know how to achieve this?

Hi fbp,

It is not clear to me, if You have a 5Vpp signal at the input, and You'd like to have a 5Vpp signal at the output, why do You need anything at all? A piece of wire does the same job with much less pain

But, anyway: an Instrumentation amplifier is sensitive to the common mode voltage of the input signal. Yes, as You already supposed, You have to give an input signal centered around the half supply. Please see the datasheet, there's a specification called "Common mode range" You are not allowed to go outside this, otherwise Your output will be distorted.

in case Yout input signal is not a differential one, but single ended, You can use an OpAmp in unity gain configuration, it will properly buffer the input signal.

 

I already told you how to do that!

What I have suggested is called a “virtual ground”, and it allows you to use signals referenced to ground that go both positive and negative. It is a way to get the advantage of dual supplies with a single supply

Sorry, I probably misunderstood your previous reply. I thought the function generator had to be at mid supply. Just to confirm. did I implement it correctly?

 

Hi fbp,

It is not clear to me, if You have a 5Vpp signal at the input, and You'd like to have a 5Vpp signal at the output, why do You need anything at all? A piece of wire does the same job with much less pain

But, anyway: an Instrumentation amplifier is sensitive to the common mode voltage of the input signal. Yes, as You already supposed, You have to give an input signal centered around the half supply. Please see the datasheet, there's a specification called "Common mode range" You are not allowed to go outside this, otherwise Your output will be distorted.

in case Yout input signal is not a differential one, but single ended, You can use an OpAmp in unity gain configuration, it will properly buffer the input signal.

My input is differential for my application, and I need high CMRR which the in-amp helps in achieving along with a unity gain of 1 initially which can be increased later if needed.

Just to give confirm, if we give an offset at the function generator, is the offset considered as Vcm?

 

My input is differential for my application

Hi,
A Differential indicates a two line signal source. ie: push pull.
If it is a Diff source what is the CMV?

Your sim shows a single line input, relative to 0v.
E

 

Hi,
A Differential indicates a two line signal source. ie: push pull.
If it is a Diff source what is the CMV?

Your sim shows a single line input, relative to 0v.
E

My input to the in-amp is from a PVDF sensor with IN+ of the in-amp to sensor positive and negative of the in-amp to sensor negative. I considered the negative of the sensor to be ground in the simulation and I used a function generator to replicate the sensor input.

Am I making the connections incorreclty?

 

Hi,
This is one option.
E
Note: over 1.5v Vin the INA clips.!!!

 

hi @fbp

This circuit meets your requirement.
E

 

Hi fbp,
This is the way I would connect the Differntial source, use the actual values in your Sensor to replace the 1k's.
E