Opampslingor

Opampslingor, or op-amp feedback loops, are arrangements in electronics where an operational amplifier sits within a feedback path that samples the output and feeds back a portion to the input to regulate amplification. The goal is to set the overall gain, bandwidth, and response of the circuit with high stability.

In practice, the feedback network consists of resistors and sometimes capacitors that set the closed-loop gain. Common configurations are the inverting amplifier, where the input goes to the inverting input, and the non-inverting input is at a reference; the non-inverting amplifier, where the input goes to the non-inverting input; and the voltage follower, which provides unity gain. Closed-loop gain is determined by the feedback network; for a non-inverting amplifier, A_CL ≈ 1 + R2/R1; for an inverting amplifier, A_CL = -R2/R1. The op-amp's open-loop gain is very large, but feedback makes the closed-loop gain stable and largely insensitive to component tolerances.

Stability depends on loop phase shift and bandwidth. If phase shift nears 180 degrees around the crossover, oscillations can occur; compensation and layout minimize this risk. Capacitive loads and the Miller effect can affect high-frequency behavior. Designers use Bode plots and phase margin to assess stability.

Common concerns include offset voltage, bias currents, noise, and power-supply rejection. Proper supply decoupling, grounding, and sometimes compensation capacitors help prevent instability. Applications include audio preamplifiers, instrumentation amplifiers, analog filters, and control loops in servo systems.

The term opampslingor is used mainly in Swedish-language texts; in English, they are usually called op-amp feedback loops.