[093] Current-Mode History and Loose Ends Part II – Middlebrook’s Model

Dr. Middlebrook's early paper on current mode indicated a current loop crossover above half the switching frequency, violating Nyquist priciples.

Introduction

In this second part of this series of articles, Dr. Ridley shows how Dr. David Middlebrook approached the analysis of current-mode control, and the consequences of the modeling approach on loop gain predictions. 

 

Current-Mode Control Circuit

Figure 1 shows a buck converter with peak current-mode control. The instantaneous value of the inductor current is added to a compensating ramp, and compared to a control reference, . The inductor current can be sensed in numerous ways, but the important thing is to make sure the sensing is an accurate representation of the real current in the inductor, without any filtering. 

Fig 1 

Figure 1: Buck Converter with Current-Mode Control

Continue reading this article?

COM_CONTENT_REGISTER_TO_READ_MORE_TEXT

AVAILABLE WORLDWIDE

contact us

Our worldwide HQ
601 E Daily Drive
Suite 112
Camarillo, CA 93010 USA

Phone US: +1 805 504 2212
Phone UK: + 44 (0)1509 276 245
Fax +1 888 339 6419
Email: info@ridleyengineering.com

Contact Us

SOCIAL NETWORK

Get Advice