Review of OP-AMPs

Operational Amplifiers perform a number of different tasks such as amplification, filtering and performing mathematical operations. This is a review of a number of concepts related to OP-AMPS.

Open Loop and Closed Loop Gain

An op-amp’s amplification (open loop gain) without any feedback in the system is usually very large (~100,000 x). The system without any feedback is referred to as an open loop system. A closed loop system provides feedback to the system.


The feedback in a system is determined by the impedances of the feedback loop and the input of the system. Furthermore, the op-amp can function as a non-inverting op-amp or an inverting op-amp, producing a system of positive or negative feedback respectively.


It must be said however that the input and feedback impedances must not be only real-values resistances. The following system may easily make use of a complex impedance, and other RC combinations to produce a filter modeled by the transfer function.



Mathematical operations using OP-Amps

Below are the following Op-Amps:

  • Summing Amplifier
  • Comparator Amplifier
  • Differentiator
  • Integrator
  • Low-Pass Filter example
  • Subtractor
  • Voltage Follower/Buffer