CMRR for Cascaded systems

Sharath Chandra

Other Parts Discussed in Thread: INA326

Hi All,

I have a question regarding calculation of CMRR of entire system.

Example: In our design we are using instrumentation amplifier INA326 at the front end which has a CMRR of 100 dB minimum, the output from INA326 is given to an ADC which has a CMRR of 65 dB.

What will be the CMRR of the combined two parts.

Regards

Sharath Chandra

over 13 years ago

0 Bruce Trump over 13 years ago

Guru 21975 points

Sharath,

The INA326 has a single-ended output so the CMRR will be totally defined by its CMRR.

Regards, Bruce.

0 Sharath Chandra over 13 years ago in reply to Bruce Trump

Prodigy 60 points

Thank you Bruce.

0 Neil Albaugh over 13 years ago

Genius 5430 points

Sharath;

In a cascaded system, the overall performance depends strongly on the gain of the first stage.

If the first stage gain is high, this amplifier determines the noise, CMR, and usually the bandwidth of the cascaded system. This is why a precision device is usually selected for the high-gain first stage. The error contributions of the following stages are minimal if the gain of the first stage is high relative to the following stages.

Amplifiers

Amplifiers forum

CMRR for Cascaded systems