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Re: Driving ADC, please help

Hi Ramon,

You could use a basic inverting opamp config with the ADA4841-1

http://www.analog.com/static/imported-files/tutorials/MT-213.pdf

Rin would be twice Rf. You could use 5V and ground as the supplies. However the limitations are you may lose some range near ground and near 5V (maybe 50-100mV depending on head/footroom spec). Also the input impedance is dictated by Rin, so not a high impedance input. Is the positive supply fixed at 12V?

Best Rgds,

Alan

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  • You could also leave the power supply on the op-amp at +12, configure the gain to give a 0-10volt output for your given input range and use a 2:1 resistive divider on the output. This also gives a measure of protection to the input stage of the ADC. In order for the resistors to be configured at a low enough value you may need to use a power op amp or a power boost stage. I successfully used this approach in a 20bit audio ADC I designed in the 90's ('Optimising the Performance of 20-bit audio ADC's', preprint 4262 , 100th AES Convention, Copenhagen, 11-14 May 1996)

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  • You could also leave the power supply on the op-amp at +12, configure the gain to give a 0-10volt output for your given input range and use a 2:1 resistive divider on the output. This also gives a measure of protection to the input stage of the ADC. In order for the resistors to be configured at a low enough value you may need to use a power op amp or a power boost stage. I successfully used this approach in a 20bit audio ADC I designed in the 90's ('Optimising the Performance of 20-bit audio ADC's', preprint 4262 , 100th AES Convention, Copenhagen, 11-14 May 1996)

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