Re: Driving ADC, please help

David, Thanks. I don't have access to your paper but I have seen something similar at the input stage of AD7671.

It uses four input pins (R, 2R, 4R, and 4R). For 0V-10V (and 2.5 Vref) both 4R's inputs are connected to Vin and both '2R & R' connected to ground.

So voltage divider is 2R || (2R||R).

According to datasheet R = 375 ohms.  (4R = 1500 ohms, 2R = 750 ohms)

So input voltage of 10V is divided by four (750 ohms || 250 ohms) to give 2.5V (as Vref).

The problem is that I am not sure how to configure the opamp. I need a single-supply opamp stable at 0.5 gain. Which configuration is better for stability? inverting or non-inverting? I don't need high speed (around 1Mhz input signal).

David, Thanks. I don't have access to your paper but I have seen something similar at the input stage of AD7671.

It uses four input pins (R, 2R, 4R, and 4R). For 0V-10V (and 2.5 Vref) both 4R's inputs are connected to Vin and both '2R & R' connected to ground.

So voltage divider is 2R || (2R||R).

According to datasheet R = 375 ohms.  (4R = 1500 ohms, 2R = 750 ohms)

So input voltage of 10V is divided by four (750 ohms || 250 ohms) to give 2.5V (as Vref).

The problem is that I am not sure how to configure the opamp. I need a single-supply opamp stable at 0.5 gain. Which configuration is better for stability? inverting or non-inverting? I don't need high speed (around 1Mhz input signal).