Stress-induced outbursts: Microphonics in ceramic capacitors (Part 1)

RE: Stress-induced outbursts: Microphonics in ceramic capacitors (Part 1)

John Kolchmeyer — Wed, 07 Jan 2026 21:59:09 GMT

What is the schematic of the circuit that generated the voltages shown in Figure 1 above? What is the volts/div of the Y axis in Figure 1?

RE: Stress-induced outbursts: Microphonics in ceramic capacitors (Part 1)

Frank Rothoff — Wed, 07 Jan 2015 11:19:53 GMT

The pyroelectric sensitivity is indeed an interesting point, thanks Niel. As John mentioned already it will be a challenge to seperate this parameter from mechanical stress artifacts. I've already some ideas which might be helpful in this.

Anyway I wanted to point out an article from our colleague who looked at this phenomenon from the other perspective. He experienced audible noise from MLCC's which is basically the same phenomenon. Here is the link: www.analog-eetimes.com/.../reducing-mlccs-piezoelectric-effects-and-audible-noise.html;news_id=222903370

RE: Stress-induced outbursts: Microphonics in ceramic capacitors (Part 1)

John Caldwell — Tue, 06 Jan 2015 15:36:59 GMT

Hi Mike, I'll have to do some digging for a document on offset voltage and stress, but this is a fairly well-known effect, especially in precision voltage references. Any mechanism which applies pressure to the die can cause a shift in offset voltage (even the mold compound of the op amp package!). Limiting this effect requires proper layout of the PCB by locating sensitive circuits in low stress areas like the outside edges of the PCB or including strain relief cut-outs on the board. Chopper and auto-zero op amps are much more resistant to these effects because they are cancelling their offset in real time. I haven't personally seen microphone effects in switched-cap filters, but the basic principles hold true. Rather than the capacitor acting as a variable resistance in the filter, it will act like a variable resistance and a voltage source due to the microphonic effects. And yes, the 2.2uF caps were definitely in the signal path and not the power supply. Although the power supply is always part of the signal path, in this application the PSRR of the amplifier would suppress any microphonic effects in the bypass capacitors.

RE: Stress-induced outbursts: Microphonics in ceramic capacitors (Part 1)

Mike Partridge — Mon, 05 Jan 2015 00:42:16 GMT

Very interesting discussion. Do you have a reference for the sensitivity of an op-amp's bias voltage to stress? You mentioned this as an aside. Also, speaking of IC performance, any comments on these effects with switch-capacitor filters? I had a problem that I attributed to these for a high-shock instrumentation application. And finally, I presume your 2.2uF cap was in the signal chain and not just power supply decoupling.

RE: Stress-induced outbursts: Microphonics in ceramic capacitors (Part 1)

John Caldwell — Mon, 29 Dec 2014 20:38:21 GMT

That's a really interesting point Neil! I may need to write another blog post in the future on that effect. The challenge will be to separate the pyroelectric effects from the piezoelectric ones in any experiment I run because a rapid change in temperature will produce mechanical stress on the dielectric as well. I suspect that attaching long leads to the capacitor and keeping it off the PCB would help reduce this effect. Thanks for your comment!

RE: Stress-induced outbursts: Microphonics in ceramic capacitors (Part 1)

Neil Albaugh — Sun, 28 Dec 2014 16:56:06 GMT

This behavior of high- titanate ceramic capacitors is not widely known and it can create problems that are puzzling; but knowing about this will help designers to avoid these types of capacitors in applications where piezoelectric effects can create microphonics.

By the way-- high- titanate ceramic capacitors are also pyroelectric, responding to sudden changes in temperature.