The direct connection from the output to the inverting input feeds any output error back into the op-amp. The device responds by changing its output until the differential voltage between its two inputs approaches zero. This feedback action maintains the tracking relationship and allows the circuit to transfer a voltage without requiring the source to supply substantial downstream current.
Bandwidth determines how accurately the follower can track signals as their frequency increases, while slew rate limits how quickly the output voltage can change. A signal may therefore show tracking errors either because its frequency exceeds the useful bandwidth or because its voltage changes too rapidly. These limitations are important when evaluating the circuit for changing engineering signals.
Offset voltage can produce a difference between the input voltage and the actual output voltage, even when the feedback connection is correct. Output-drive limits determine whether the op-amp can supply the current demanded by the following circuit. Consequently, a follower may isolate stages effectively while still showing a voltage error or inadequate output performance under demanding load conditions.
Apply the signal to the non-inverting input and connect the output directly to the inverting input. During development, compare the output with the applied input across the intended operating conditions. Checking tracking behavior, signal frequency, voltage-change rate, offset, and downstream loading helps reveal whether the selected op-amp can meet the engineering requirements.
It is useful when a sensor, reference voltage, or other high-impedance source could be disturbed by the next circuit stage. The follower presents high input impedance to the source while providing low output impedance for the load. This separation reduces loading effects, helping preserve the source voltage as it moves into downstream measurement or processing circuitry.
Placed between stages, the circuit can reduce the interaction between a voltage-producing source and a current-demanding load. That isolation helps downstream circuitry receive a more practical drive without significantly altering the source voltage. Its usefulness still depends on matching the op-amp's bandwidth, slew rate, offset voltage, and output-drive capability to the signals and loads involved.