Samuel, When looking at the TLA2024 input impedance you should consider both the common-mode and differential impedance. When operating in the ±2.048 V range, the common mode input impedance will be at 6 MΩ and the differential input impedance will be 4.9 MΩ. The input impedance is modeled as shown in Figure 9 in the datasheet. You can calculate exactly what the error would be based on the above structure. However, with a 10kΩ parallel resistance, this would already cause a 0.3% gain error. I would note that the TLA2024 already has a typical 0.05% gain error (not maximum) which is the customer's target accuracy. If you need better performance, this may not be the device to use. Joseph Wu
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