Amr Wael
Member level 5
Hello ,
I simulated instrumentation amplifier INA849 in texas instruments PSPICE. The schematic is shown and it's very simple , a resistive divider followed by the opAmp , as you can see the resistance which calibrates the gain is absent in order to get a unity gain.
The second photo shows an AC frequency sweep versus the output voltage in case of using Resistors of 4.9M and 100k for the resistive divider. The third photo shows an AC frequency response versus the putput voltage in case of using resistors of 490k and 10k. Although the divider's ratio is the same you can notice that the bandwidth is now 10 times better. in the data sheet the bandwidth is 28 MHz at unity gain so I 've been really upset before solving this problem. I understand that the super high input impedance mentioned is the data sheet is changed according to the resistive network that I am using with the opAmp but how exactly is it affecting my bandwidth in such a way? what's the reason/formula behind that effect?
Thank you very much in advance.
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I simulated instrumentation amplifier INA849 in texas instruments PSPICE. The schematic is shown and it's very simple , a resistive divider followed by the opAmp , as you can see the resistance which calibrates the gain is absent in order to get a unity gain.
The second photo shows an AC frequency sweep versus the output voltage in case of using Resistors of 4.9M and 100k for the resistive divider. The third photo shows an AC frequency response versus the putput voltage in case of using resistors of 490k and 10k. Although the divider's ratio is the same you can notice that the bandwidth is now 10 times better. in the data sheet the bandwidth is 28 MHz at unity gain so I 've been really upset before solving this problem. I understand that the super high input impedance mentioned is the data sheet is changed according to the resistive network that I am using with the opAmp but how exactly is it affecting my bandwidth in such a way? what's the reason/formula behind that effect?
Thank you very much in advance.
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