Power Operational Amplifier Stabilization Techniques

Focus:

In this 5-minute video, the presenter demonstrates four methods for stabilizing power amplifiers using an EK09 evaluation kit, which contains a PA96 power amplifier. The presenter describes the test setup and the value of using low voltage power supplies for testing. He looks at open loop frequency response and phase gain on the data sheet, and explains how these plots indicate the amplifier will be unstable. He then explains and demos the four methods of compensation: 1) adding a capacitor (phase compensation), 2) adding a capacitor to the feedback loop, 3) adding an isolation resistor between the load and the amplifier, and 4) adding noise gain. Tradeoffs and limitations of each method are discussed.

What you’ll learn:

• How to stabilize a power op amp
• How to understand tradeoffs of different amplifier stabilization methods

Notes:

The presentation references Cirrus Logic application note AN 47, which goes into much greater detail about the causes and treatments for amplifier instability as well as methods for testing stability. This app note is online at www.cirrus.com/en/pubs/appNote/Apex_AN47U_A1.pdf.

View the Source

Author & Publication:

Daniel Sigety, Applications Engineer, Cirrus Logic, Apex Precision Power , Vendor website, Feb 01 2010

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