AnsweredAssumed Answered

Instrumentation amplifier AD8421 at higher gain ?

Question asked by agarwals@imec.be on Aug 31, 2015
Latest reply on Sep 3, 2015 by agarwals@imec.be

Hello,

 

I intend to use low-noise instrumentation amplifer (AD8421) to drive my ADC. Since, ADC has the input range of +/- 5V and my input signal is in uV, I will have to configure the IA in high gain mode. May I please ask the following questions in this regard :

 

1. Can I confirm if the maximum gain that can be set is 10,000. (it shows 1000 in the parametric search table !)

2. What is the bandwidth of this instrumentation amplifier in high gain configuration (eg : gain = 5000 or gain = 10000)

Specs only tells small signal bandwidth for certain gain

G = 1 -> 10MHz

G = 10 -> 10Mhz

G = 100 -> 2Mhz

G = 1000 -> 0.2Mhz

 

Is it safe to simply linearly interpolate the bandwidth for higher gain from the above trend ?

 

3. Do you think if there can be any issues (apart from bandwidth going down) if I configure this instrumentation amplifier for high gain like 5000 and 10000 (eg : CMRR, slew rate, non-linearity etc.)

 

4. Can the "REF" pin be driven by the voltage source to create the required offset in the IA output voltage (according to the input range of ADC) ?

 

Thanks for a prompt response from your side,

 

Thanks

 

Regards

 

Saurabh

Outcomes