Re: Noise reduction: Inductor vs. Capacitor

jidan1@xxxxxxxxxxx wrote:
Hi,

It is common to use a bypass capacitor connected in parallel from VCC
to GND to reduce noise on the power line. I have seen also inductors
connected in series to do the same thing. I have seen also both (cap &
inductor) being used at the same circuit to reduce noise on the power
line. In my opinion, the caps are smaller and more cheaper than
inductors, so why use an inductor?

Thanks for any replies,
JJ


In addition to the other responses, inductors (which may be ferrite beads) are _often_ used where the load is (quasi) constant current, such as ECL, CML and the like.

There are always current spikes when the transistors switch, which must be suppressed to the power supply - and inductors are the perfect tool for the job. The local caps provide the current and maintain the rail voltage at the device, of course.

Cheers

PeteS
.

Relevant Pages

  • Re: questions on power supply for audio amp
    ... >>at the power pin of the amplifier, ... >>some high frequency noise on the supplies that is getting thru the amp. ... >>since they go away when I turn the power off while the caps are still ... > coming in OR the amplifier is generating RF. ...
    (sci.electronics.design)
  • Re: Determine switching frequency of photocoupler
    ... I added 0.1uF X7R caps across ... the power and ground pins of every chip, this did not seem to effect ... Measuring the ground noise was running me in circles and I kept ... wire) on the h bridge, then probe to a via which is the same node, ...
    (sci.electronics.design)
  • Re: Noise reduction: Inductor vs. Capacitor
    ... to GND to reduce noise on the power line. ... I have seen also inductors ... There are things you can do with inductors that you can't just with caps alone! ...
    (sci.electronics.basics)
  • Noise reduction: Inductor vs. Capacitor
    ... to GND to reduce noise on the power line. ... I have seen also inductors ... I have seen also both (cap & ...
    (sci.electronics.basics)
  • Re: Noise reduction: Inductor vs. Capacitor
    ... to GND to reduce noise on the power line. ... I have seen also inductors ... Capacitors are cheaper. ...
    (sci.electronics.basics)