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Bessel Filter Lowpass Prototype Element Values

Simulations of Normalized and Denormalized LP, HP, BP, and BS Filters

Prototype Lowpass Filter Schematics (Butterworth, Chebyshev, Bessel) - RF Cafe

Lowpass Filters
(above)

Highpass Filters
(above)

Bandpass and Bandstop Filters
(above)

A Bessel filter is a filter whose impulse response is a Bessel function. Bessel filters are designed to give maximally flat group delay and maximally linear phase change across the band and into the transition region. They are very close to Gaussian type filters.

The table below lists prototype element values for the normalized lowpass function, which assumes a cutoff frequency of 1 rad/sec and source and load impedances of 1 Ω. Either an input capacitor (top reference line in table) or an input inductor (bottom line in table) can be used.

Convert values to other cutoff frequencies, impedances, and to highpass, bandpass or bandstop using denormalization equations.

Prototype filter schematic - capacitor input - RF Cafe

Capacitor Input

Prototype filter schematic - inductor input - RF Cafe

Inductor Input

 Capacitor Input, RS=RL=1 Ω, f=1 rad/sec
OrderC1L2C3L4C5L6C7L8C9L10
12.000         
20.5762.148        
30.33740.97052.2034       
40.23340.67251.08152.2404      
50.17430.50720.8041.1112.2582     
60.13650.40020.63920.85381.11262.2645    
70.11060.32590.52490.7020.8691.10522.2659   
80.09190.27190.44090.59360.73030.86951.09562.2656  
90.0780.23130.3770.51080.63060.74070.86391.08632.2649 
100.06720.19980.3270.44540.55280.64930.7420.85611.07812.2641
 L1C2L3C4L5C6L7C8L9C10
 Inductor Input, RS=RL=1 Ω, f=1 rad/sec
Related Pages on RF Cafe
- How to Use Filter Equations in a Spreadsheet
- Filter Transfer Functions
- Filter Equivalent Noise Bandwidth
- Filter Prototype Denormalization
- 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
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