Can somehow show me a DC circuit analysis for this INA13X part, starting with series resistor Rs, then using differential amplifier, via BJT transistor, to the output voltage formula.
Thanks
Hello Marko,
This sounds rather academic so opposed to providing the direct answer I'd rather provide the theory and a SPICE simulation and let you derive the equations.
Like all amplifiers, the difference amplifier in this device will use feedback to drive the positive and negative inputs to the same potential (establish virtual short). In the INA13X, the amplifier drives the base of the BJT with a current that causes the collector current to drop the appropriate voltage across the 1k positive input resistor such that the positive and negative inputs are equal.
This can be seen in the image and SPICE models below. It should be noted that in the real device the base current is accounted for and does not appear as an error like it will in this over-simplified block diagram.
Regards,
Collin Wells
Precision Linear
