Op-amp Finite Bandwidth Part 3/3: Compensation [Op-amp TS 16]

Op-amp tutorial series episode 16. In this video we explain the concept of op-amp compensation, discussing the internal compensation applied to modern op-amps, and using an example circuit with the AD8618 we explain how to compensate op-amps (externally) in-depth.

The frequency compensation techniques we use with the AD8618 are reducing the divider resistances to compensate for a parasitic capacitance on the inverting input, using lead compensation in the form of a feed forward capacitor (or feed-forward capacitor) on the resistive divider, and using an isolation resistor to compensate the negative phase-shift introduced by the op-amp circuit's load capacitance.

We also briefly touch on a few more compensation methods, including gain compensation, lag compensation, and in-the-loop compensation.

Concepts discussed:
op-amp internal compensation
divider resistance changes compensation
lead compensation with feed forward capacitor
isolation resistor compensation for capacitive loads
gain compensation
lag compensation
in-the-loop compensation for capacitive loads


00:00 Intro
00:54 Compensation Overview
01:45 Internal Compensation
05:44 Exernal Compensation
09:15 Comp. Example Starting Point
10:20 Divider Resistances Adjustment
12:27 Lead Compensation
16:49 Isolation Resistor
21:21 Results of Compensation
23:40 Advanced Comp. Methods
28:15 Outro