•−•  ••−•    −•−•  •−  ••−•  •
RF Cafe Morse Code >Hear It<

Job Board

About RF Cafe™

Sitemap

RF Cafe Software

RF Cascade Worbook
 RF Cascade Workbook 2005 - RF Cafe
Calculator Workbook
RF Workbench
Smith Chart™ for Visio
Smith Chart™ for Excel
RF & EE Symbols Word
RF Stencils for Visio

Your RF Cafe
Progenitor & Webmaster

Click here to read about RF CafeKirt Blattenberger
BSEE
KB3UON
EIEIO

Carpe Diem!
(Seize the Day!)

5th MOB:
My USAF radar shop

Airplanes and Rockets:
My personal hobby website

Equine Kingdom:
My daughter Sally's horse riding website

Filter Equivalent Noise Bandwidth

A filter's equivalent noise bandwidth (EqNBW) is the bandwidth that an ideal filter (infinite rejection in the stopband) of the same bandwidth would have. EqNBW is calculated by integrating the total available noise power under the response curve from 0 Hz to infinity Hz. In practice, integration only needs to be carried out to about the point of thermal noise. The steeper the filter skirts (higher order), the narrower the range of integration needed to get an acceptable approximation. Integration needs to be done in linear terms of power (mW, W, etc.) rather than in dB.

The values in the following table are for normalized lowpass filter functions with infinite Q and exact conformance to design equations. If you need a better estimation than what is presented here, then a sophisticated system simulator is necessary.

Butterworth
(fco = 3 dB)
Chebyshev
(fco = ripple)
Bessel
(fco = 3 dB)
Order EqNBW
1 1.5708
2 1.1107
3 1.0472
4 1.0262
5 1.0166
6 1.0115
7 1.0084
8 1.0065
9 1.0051
10 1.0041
Ripple 0.01 dB 0.1 dB 0.25 dB 0.5 dB 1.0 dB
Order
2 3.6672 2.1444 1.7449 1.4889 1.2532
3 1.9642 1.4418 1.2825 1.1666 1.0411
4 1.5039 1.2326 1.1405 1.0656 0.9735
5 1.3114 1.1417 1.0780 1.0208 0.9433
6 1.2120 1.0937 1.0448 0.9970 0.9272
7 1.1537 1.0653 1.0251 0.9828 0.9175
8 1.1166 1.0471 1.0125 0.9736 0.91133
9 1.0914 1.0347 1.0038 0.9674 0.9071
10 1.0736 1.0258 0.9977 0.9629 0.9041
Order EqNBW
1 1.57
2 1.56
3 1.08
4 1.04
5 1.04
6 1.04

Reference: Filter Design, by Steve Winder

Related Pages on RF Cafe
- Filter Transfer Functions
- Filter Equivalent Noise Bandwidth
- Filter Prototype Denormalization
- Filter Design Resources
- Bessel Filter Poles
- Bessel Filter Prototype Element Values
- Butterworth Lowpass Filter Poles
- Butterworth Filter Prototype Element Values
- Chebyshev Lowpass Filter Poles
- Chebyshev Filter Prototype Element Values
- Monolithic Ceramic Block Combline Bandpass
  Filters Design
- Coupled Microstrip Filters: Simple Methodologies for
  Improved Characteristics

Try Using SEARCH to Find What You Need.  >10,000 Pages Indexed on RF Cafe !

Copyright 1996 - 2016
Webmaster:  Kirt Blattenberger, BSEE - KB3UON
Family Websites:  Airplanes and Rockets | Equine Kingdom

All trademarks, copyrights, patents, and other rights of ownership to images
and text used on the RF Cafe website are hereby acknowledged.