I think I have a simple (but still to me confusing) question regarding the gain bandwidth product (GBP) of an instrumentation amplifier: Datasheet (AD8237)

I have sensors that change their output values very slowly (measuring sun irradiation) and I want to amplify their small output voltage (between 0-20mV) to 0-2V (so I will use a gain of 100) using the in-amp mentioned above. (The amplified signal then will be forwarded to an ADC that will take one reading per second or less.)

Now the AD8237 has a BW pin, that allows me to change the compensation and increase/decrease the GBP of the amp. On page 20 in the datasheet it says:

The AD8237 includes an RFI filter to remove high frequency out-of-band signals without affecting input impedance and CMRR over frequency. Additionally, there is a bandwidth mode pin to adjust the compensation. For gains greater than or equal to 10, the bandwidth mode pin (BW) can be tied to +VS to change the compensation and increase the gain bandwidth product of the amplifier to 1 MHz. Otherwise, connect BW to −VS for a 200 kHz gain bandwidth.

As this paragraph seems to answer some of the questions I have, it also confuses me at the same time. I researched what GBP is (in my opinion nicely described at learningaboutelectronics.com)

In my case, should I connect the BW pin to +VS (increase the gain bandwidth product of the amplifier to 1 MHz) or to -VS (for a 200 kHz gain bandwidth product)? As I do not require speed and only care about DC signal amplification, I think that the lower GBP would be sufficient in my case. But on the other hand, they say for gains equal or higher than 10 the higher BGP should be used?

Also what advantages/disadvantages do I get, considering both possible cases (in case of the lower 200kHz BGP or the higher 1MHz BGP)?

Would I care about the BGP in my DC scenario at all?

As the datasheet is little confusing for me regarding this, I would appreciate your help here.

Thank you!

  • 1
    \$\begingroup\$ Expect the higher gain-bandwidth to produce more random noise. In fact, install and R+C filter between the INA and the ADC, with F3dB of 10Hz. Use 16,000 ohms and uF. \$\endgroup\$ – analogsystemsrf Jan 19 '19 at 3:59
  • \$\begingroup\$ @analogsystemsrf: Ok, so I can set the INA to the low bandwidth mode for my DC case without any problems? (and then use the RC filter in addition)? \$\endgroup\$ – Henry Jan 19 '19 at 14:02

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