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Ansoft Designer / Ansys Designer 在线帮助文档：

Nexxim Simulator >
Nexxim Component Models >
Nexxim Filters >
   Elliptic Low Pass Filter       

Elliptic Low Pass Filter

Netlist Syntax

An instance of an elliptic low pass filter has three netlist variants:

Axxx n1 n2 N=val [AMAX=val] [AMIN=val] FC=val [R1=val] [R2=val] [IL=val] COMPONENT=elliptic_lowpass_filter

Axxx n1 n2 KP=val [AMAX=val] [AMIN=val] FC=val [R1=val] [R2=val] [IL=val] COMPONENT=elliptic_lowpass_filter

Axxx n1 n2 FS=val [AMAX=val] [AMIN=val] [R1=val] [R2=val] [IL=val] COMPONENT=elliptic_lowpass_filter

n1 and n2 are the nodes connected to the filter. The entry COMPONENT=elliptic_lowpass_filter is required.

Netlist Example

A22 1 2 N=5 FC=1e9 AMAX=0.5 AMIN=45
+ COMPONENT=elliptic_lowpass_filter

Notes

1. The elliptic filter model represents three separate components: ELHPF_N, ELHPF_KP, and ELHPF_FS. The parameters N, KP, and FS are mutually exclusive in the syntax.

2. The elliptic filter has equal loss maxima in the pass band and equal loss minima in the stop band. The elliptic filter provides a sharp transition region for the lowest possible order.

3. The magnitude of the transfer function of the elliptic filter (high-pass prototype) is equal to:

where:

R_n(ω, IL) is the Nth-order Chebychev rational function,

e = 10^0.1AMIN,

w = 2pf,

4. The loss in dB is the inverse of the transfer function:

where:

R_n is the Nth-order Chebychev rational function,

e = 10^0.1AMIN,

A normalized band pass filter is designed for w_C=1. A frequency transformation is performed for the band reject filter:

5. The first netlist variant specifies AMAX, AMIN, FC, and N. The order of the filter determines the sharpness. The order defines the number of reactive elements needed to implement the filter. The range for N (order of filter) is from 2 to 15. Orders higher than 15 cannot be simulated.

6. The second netlist variant specifies AMAX, AMIN, FC, and KP. The order of the filter is then calculated from the value of the given parameters.

7. The third netlist variant specifies AMAX, AMIN, FC, and FS. The required order of the filter is calculated from the parameters given.

References

[1] Approximation Methods for Electronic Filter Design, Richard W. Daniels, McGraw-Hill, Inc.

[2] Handbook of Filter Synthesis, Anatol I. Zvered, John Wiley & Sons, Inc. 1967.

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