Feedback topology: Is output voltage or current being sampled in this circuit?

The discussion centers on identifying the feedback topology in an op-amp circuit where input and feedback currents mix. Analysis using Thevenin equivalents shows the circuit behaves as a basic inverting amplifier with voltage gain Av = -Rf/Rs, indicating the output quantity sampled is voltage, not current. The virtual ground at the inverting input ensures input current (Is) approximately equals output current (Io), but the output is a voltage across the feedback resistor Rf, which is not considered a load. The necessity of a grounded reference for the load is debated, clarifying that without a proper load to ground, current flow at the output is undefined. Local feedback in transistor circuits, such as emitter degeneration via Re, is distinguished from true negative feedback, as it stabilizes gain but does not feed output back to input through a feedback network. Recommended literature includes "Audio IC Op Amp Applications" by Walter G. Jung for further understanding of op-amp feedback and design.
Summary generated by the language model.