Objective:

To help understand more about high speed op amps, specifically op-amp feedback and application.

Online Seminar:

LMH High Speed Operational Amplifiers, August 23, 2001, Martin Giles
Find out the latest information on National's new LMH process, including its core features and system benefits. There will be a presentation of several applications, and an overview of released products.

Reading Assignment:

OA-20 Application note, "Current Feedback Myths Debunked", provides a basic understanding of current-feedback in high-speed op-amps.

Additional Resources

OA-13 Application note, "Current Feedback Loop Gain Analysis and Performance
Enhancement", provides more information on current feedback and gives
information on how to improve high speed performance.

Research Assignment:

• The LMH op-amps are replacing the CLC op-amps. Which op-amp is equivalent to the CLC404? (Hint: Go to national's website to the amplifiers home page, find the Comlinear Op Amp Obsolescence Information section.) check answer                   
• Go into the datasheet of the op-amp above and look at the graph that shows the non-inverting small signal response. For Av=+2, what would be the -3dB BW? What is the recommended value of feedback resistor (Rf)? How much frequency response peaking is associated with this value of feedback resistor? check answer                   
• In a Current Feedback Amplifier, what is analogous to the Voltage Feedback Amplifier's Loop Gain and how is it measured? check answer

Program Coordinator/Professor

Hooman Hashemi
Hooman Hashemi is a Principal Applications Engineer, Amplifiers Product Group, Santa Clara, who joined National Semiconductor Corp. in 1995. He received a BSEE at San Jose State University and a MSEE at Santa Clara University.

Quiz:

Take a quiz to check your understanding of this subject. Click here.
Answer all questions correctly to receive a certificate from Dean Bob Pease.