design

Design stepped impedance low pass filter around desired cut-off frequency

Since R2021b

Syntax

sifilter = design(sifilterobj,frequency)

sifilter = design(___,Name=Value)

Description

sifilter = design(sifilterobj,frequency) designs a stepped impedance low pass filter around the cut-off frequency.

sifilter = design(___,Name=Value) designs a stepped impedance low pass filter with additional options specified by name-value arguments.

Note

• PCB components designed using the design function operate around the specified frequency with a 10-15% tolerance.

• The design for stepped impedance low pass filter is based on analytical equations. Analyzing the parameters using EM-simulation model causes a shift in the cut-off frequency towards the lower end of the frequency range. This is an expected behavior due to the coupling effect.

Examples

Design Stepped Impedance Low Pass Filter at 2.5 GHz

Design a sixth order stepped impedance low pass filter at 2.5 GHz with 20 ohm low impedance line, 120 ohm high impedance line on FR4 substrate of thickness 1.58 mm.

sifilter = filterStepImpedanceLowPass(FilterOrder=6,Height=1.58e-3) ;
Sub  = dielectric(Name='Fr4',EpsilonR=4.2,LossTangent=0.02,Thickness=1.58e-3);
sifilter.Substrate = Sub;
sifilterobj = design(sifilter,2.5e9,Z0=50,LowZ=20,HighZ=120);

View the filter.

show(sifilterobj);

Input Arguments

sifilterobj — Stepped impedance low pass line filter

filterStepImpedanceLowPass object

Stepped impedance low pass filter, specified as a filterStepImpedanceLowPass object.

Example: sifilterobj = filterStepImpedanceLowPass; design(sifilterobj,2e9) designs a coupled line filter around a frequency of 2 GHz.

frequency — Design frequency of stepped impedance low pass filter

real positive scalar

Design frequency of the stepped impedance low pass filter, specified as a real positive scalar in hertz.

Example: 5e9

Data Types: double

Name-Value Arguments

Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Example: Z0=75

Z0 — Reference impedance

50 (default) | positive scalar

Reference impedance, specified as a positive scalar in ohms.

Data Types: double

LowZ — Low impedance line

20 (default) | positive scalar

Low impedance line, specified as a positive scalar in ohms.

Data Types: double

HighZ — High impedance line

120 (default) | positive scalar

High impedance line, specified as a positive scalar in ohms.

Data Types: double

FilterType — Type of filter

'Butterworth' (default) | positive scalar

Type of filter, specified as 'Butterworth', or 'Chebyshev'.

Data Types: char | string

RippleFactor — Passband factor of Chebyshev filter

0.01 (default) | positive scalar

Passband factor of the Chebyshev filter, specified as positive scalar in decibels. For Butterworth filter, the passband factor is not required.

Data Types: double

Output Arguments

sifilter — Stepped impedance low pass filter around specified frequency

filterStepImpedanceLowPass object

Stepped impedance low pass filter around specified frequency, returned as a filterStepImpedanceLowPass object.

Version History

Introduced in R2021b