AEi Systems, LLC
(310) 216-1144

8 of 10 Design Issues I Find Are Due to A Single Problem
Steve Sandler, AEi Systems

Latest News & Articles

The vast majority of design issues are directly or indirectly attributable to control loop stability. The most common offenders:

  • Linear regulators
  • Voltage references
  • Op-amps

The control loop stability of these devices can propagate through an entire system. Symptoms include:

  • EMI
  • Increased circuit noise
  • Clock jitter

These are all simple circuits, so why is this a common issue?

We are not clear on the definition of stability
In the high-reliability world, including satellite systems, where I do most of my troubleshooting, stability means a minimum phase margin of 30 degrees and a gain margin of 6dB at the end of life, including all component variations and environmental factors. There are guidelines that define the stability margin limits, and one of our tasks is to ensure that margin.

This requirement is not well aligned with the information given out by manufacturers. They generally do not provide quantifiable metrics for the stability of their devices. In many cases, the devices will not meet a 30-degree phase margin even typically when coupled with low-ESR capacitors. The definition of stability in the semiconductor world seems to be whether the circuit has a stability margin that is greater than zero.

Component manufacturers drive us to it through recommendations
In some cases, manufacturers provide recommendations. One example I often use is the REF02 voltage reference. The manufacturer's datasheet highly recommends the addition of a 0.1uF output capacitor on the voltage reference. Read More...

New Articles
New Videos

AEi Systems Services:
Worst Case Circuit Analysis for Power, RF, Linear and Digital Systems
• WCCA Plan Development and WCCA Bidding
• Electrical SDRLs: MTBF/Reliability, FMECA, Stress & Derating, and Radiation Analysis
Signal Integrity Analysis: Decoupling, Noise, Crosstalk, Compatibility!
• Component and Circuit Test and Characterization
• Hardware/Failure Analysis & Troubleshooting
SPICE Modeling

AEi Systems achieves results:
• We have brought together top engineers with focused backgrounds in reliability, design and test
• We dig deeper to get it right, because we believe it's simply unacceptable to be complacent
• We believe in making sure things work in tough places for a long time

AEi Systems is a unique resource:
• We do it faster, better and at a lower cost than in-house resources
• We help our customers meet their deadlines, yet we never sacrifice thoroughness

How can we help you? Contact us for more specific information or a no-obligation quotation.

Having trouble reading this email? View it in your browser.