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OPA860/861 Question about In-Amp in sboa117 documentation
I'm looking at figure 11 in this document:
This is kind of a dumb question but how do I select Rcomp and Ccomp for the propagation delay? Since I want a current output, I'm thinking about putting another OTA in a current summing configuration instead of the opamp.
The propagation delay on the output of the OPA861 will be controlled by the capacitor, noted Ccomp. If the capacitor is greater on one side than the other, the pole formed by the output impedance of the C output (current source) and Ccomp will be compensating the propagation delay of the OPA861 in the current inverter configuration. The Rcomp is there to provide some isolation of the parasitic capacitance of the following stage.
The spice model of the OPA861 should help you set this value. I believe a few pF to be sufficient for Ccomp and a few 100s ohm for Rcomp. I attached a simplified model of the output of the Coutput with the Comp and Rcomp to describe this.3858.OPA861 propagation delay model.TSC.
The exact value for the output impedance can be found in the OPA861 datasheet.
Thank you. Your response was very helpful but I can't to open the .tsc file.
.tsc files are TINA-TI TINA Schematic files. TINA can be downloaded from the TI website.
I attached a pdf version of the schematic as well.2110.OPA861 propagation delay model.pdf
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