Which type of capacitor has lower 1/f noise: MLCC or film?

  • Thread starter Thread starter eq1
  • Start date Start date
  • Tags Tags
    Noise
Click For Summary

Discussion Overview

The discussion centers on the comparison of 1/f noise characteristics between different types of capacitors, specifically MultiLayer Ceramic Capacitors (MLCC) and film capacitors, in the context of low noise applications such as capacitive feedback transimpedance amplifiers (TIAs). Participants explore how dielectric materials influence inherent noise levels.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant is investigating the impact of capacitor choice on input referred noise in a low noise TIA, specifically comparing a 47pF 0603 film capacitor to an NP0 MLCC.
  • Another participant asserts that capacitors do not generate 1/f noise in the same manner as resistors, suggesting that MLCCs are leaky and may produce noise when used for low-power signals.
  • A later reply acknowledges that while capacitors do exhibit some level of 1/f noise, it is generally lower than that of resistors, and notes that dielectric materials can introduce noise, particularly in RF/MW applications.
  • There is a suggestion that the noise characteristics of capacitors may not be a significant concern for the specific application being discussed.

Areas of Agreement / Disagreement

Participants express differing views on the extent and significance of 1/f noise in capacitors. While some agree that capacitors do not generate 1/f noise like resistors, others point out that all materials exhibit some level of noise, leading to an unresolved discussion on the implications for specific applications.

Contextual Notes

There are limitations regarding the assumptions about noise generation in capacitors and the specific conditions under which the noise characteristics may vary. The discussion does not resolve the complexities of how dielectric choice impacts noise levels in practical scenarios.

eq1
Messages
206
Reaction score
71
I am working on a low noise capacitive feedback TIA where I need to achieve a pretty low voltage/current input referred noise and so I started researching components. For the resistors and transistor I know about 1/f noise, etc. and I'm confident in my choice but it dawned on me, what about the capacitor?

I've read about piezo effects in ceramics, buzz in film, and all the various ways capacitance can change on you but I haven't seen much on how dielectric choice effects inherent noise.

Basically I am trying to pick between a 47pF 0603 film or a NP0 MLCC. It seems like antidotally, in the acoustic band anyway, they both have pros/cons. Input referred noise at the level I'm working at is a pretty labor intensive measurement to take so I'm really hoping to pass on the first try. :)
 
Last edited:
Engineering news on Phys.org
TIA = transimpedance amplifier

Capacitors do not generate 1/f noise in the same way a resistor does.

MLCC = MultiLayer Ceramic Capacitor = skycap; are designed for use on power supplies, when they leak they will self-heal if across a low impedance supply, but they remain leaky if used for low-power signals. While they are leaky they will make noise.

Use silver-mica, or film, not MLCC for signals.
 
  • Like
  • Informative
Likes   Reactions: berkeman, Tom.G and eq1
Baluncore said:
Capacitors do not generate 1/f noise in the same way a resistor does.

On second thought that must be true. If it wasn't we couldn't low pass the white noise spectrum of the resistor, and clearly noise shaping is a thing.

Somehow I am just really surprised by that. I am probably overthinking it. :)
 
It certainly isn't the case that there is NO 1/f noise in capacitors, pretty much everything exhibits 1/f noise at some level, but the 1/f noise should under most circumstances be lower than in a resistor.

Specifically, the dielectrics are intrinsically noisy at some level (even really pure silicone exhibits some dielectric noise) and in some applications this can be problematic, especially for RF/MW applications.

That said, I very much doubt this is something you could need to worry about in this application.
 
  • Informative
Likes   Reactions: eq1

Similar threads

Which of these op amp configurations has the least noise?
  • · Replies 1 ·
Replies
1
Views
2K