Reducing MLCCs’ piezoelectric effects and audible noise

With the increasing popularity of MLCCs (or ceramic capacitors) in electronic circuits due to their low cost and low profile, their inherent piezoelectric effect and the resultant audible noise can become a problem, as more and more electronic devices are handheld.
The multilayer ceramic capacitor (MLCC) has numerous advantages compared to commonly used tantalum electrolytic capacitors, including:

•very low equivalent series resistance (ESR),

•very low equivalent series inductance (ESL),

•lower aging and a high reliability of its dielectric.

However, like all ferroelectric dielectrics, it is affected by the piezoelectric effect: certain materials generate an electric potential or electric field on the surface by mechanical deformation. If the dielectric is now subjected to a varying electric field intensity that operates at a frequency which is located in the audible frequency range of the human ear (20 Hz to 20 kHz), the capacitor produces noise, the so-called audible noise.

A MLCC alone is in most cases not sufficient to generate a problematic or disruptive Sound Pressure Level (SPL). But when it is soldered on a PCB board, the MLCC generates a spring-mass system, which increases or dampens the oscillations depending on the frequencies.

This article investigates and discusses Influences, possible causes, and solutions to reduce audible noise in ceramic capacitors, including:

•Experimental environment and setup
•Frequency influence

•Signal characteristics influence

•Component characteristics influence

•PCB board influence

•Audible noise in electronic circuitry
•Alternatives to MLCCs

Click to read “Reducing MLCCs’ piezoelectric effects and audible noise ,” which appeared in EE Times-Europe .

About the author
Nicolas Guibourg joined Texas Instruments Germany as systems engineer in 2006, where he works on application support and new product definition for the Display Power Converters group. He has an electrical engineering degree from ISEN – Institut Supérieur de l’Électronique et du Numérique (France).

Editor's note : Liked this? Want more?

If you are interested in “analog” issues such as signal input/output (sensors and transducer, real-world I/O); interfacing (level shifting, drivers/receivers); the signal chain; signal processing (op amps, filters, ADCs and DACs); and signal integrity, then go to the Planet Analoghome page for the latest in design, technology, trends, products, and news. Also, sign up for our weekly Planet Analog Newsletter.

If you are interested in “power” issues such as components; efficiency; thermal concerns; AC/DC and DC/DC supply topologies; batteries; supply ICs; complete supplies; single- and multi-rail management; and supply monitoring: then go to the Power Management Designline home page for the latest in design, technology, trends, products, and news. Also, sign up for our weekly Power Management Designline Newsletter.

1 comment on “Reducing MLCCs’ piezoelectric effects and audible noise

  1. ljskdofijwef
    August 16, 2015

    1. Talk with recent clients Ask agents to provide a list of what they've listed and sold in the past year, with contact information, says Ron Phipps, past president of the Chicago-based National Association of Realtors, or NAR. Before you start calling the names, ask the agent if anyone will be “particularly pleased or particularly disappointed,” he says. With past clients, “I'd like to know what the asking price was and then what the sales price was,” says William Poorvu, adjunct professor emeritus at Harvard Business School and co-author of “The Real Estate Game: The Intelligent Guide to Decision-making and Investment.” And, if you're the seller, ask if these past properties are similar to yours in price, location and other salient features, Poorvu says. What you want is someone who specializes in exactly what you're selling. SHARE THIS STORY LinkedIn Delicious Reddit Stumbleupon Email story Another good question for sellers is: How long has the home been on the market?

    2. Look up the licensing States will have boards that license and discipline real estate agents in those states, says Phipps. Check with your state's regulatory body to find out if the person is licensed and if there have been any disciplinary actions or complaints, or check to see if the information is posted online.

    3. Pick a winner Peer-given awards count, says Phipps. One that really means something is the “Realtor of the Year” designation awarded by the state or local branch of NAR. “These agents are the best as judged by their peers,” he says. “That's a huge endorsement.”

    4. Select an agent with the right credentials Just as doctors specialize, so do real estate agents. And even generalists will get additional training in some areas. So that alphabet soup after the name can be an indication that the person has taken additional classes in a certain specialty of real estate sales. Here's what some of the designations mean:

    5. Research how long the agent has been in business You can often find out how long the agent has been selling real estate from the state licensing authority. Or, you can just ask the agent. “If they haven't been in business five years, they're learning on you and that's not good,” says Robert Irwin, author of “Tips & Traps When Buying a Home.” Ultimately, what you're looking for is someone who is actively engaged in a particular area and price range, says Phipps. You'll want to know what knowledge of those two factors they can demonstrate and “what kind of market presence they have,” he says.

    6. Look at their current listings Check out an agent's listings online, says Brobeck. Two places to look are the agency's own site and, a website that compiles properties in the Multiple Listing Service into a searchable online database. Most buyers start their search on the Internet, and you want an agent who uses that tool effectively. “A key thing is an attractive presentation on the Web,” says Brobeck. You also can look at how closely the agent's listings mirror the property you want to buy or sell. Are they in the same area? Is the price range similar? And does the agent have enough listings to indicate a healthy business but not so many that you'd just be a number?

    7. Ask about other houses for sale nearby A good agent should

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.