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Lowpass pi filter


Use the lclowpasspi class to represent a lowpass pi filter as a network of inductors and capacitors.

The LC lowpass pi network object is a 2-port network as shown in the following circuit diagram.

2-port LC lowpass pi network

In the diagram, [L1, L2, L3, ...] is the value of the 'L' object property, and [C1, C2, C3, ...] is the value of the 'C' object property.




h = rfckt.lclowpasspi returns an LC lowpass pi network object whose properties all have their default values.

h = rfckt.lclowpasspi('Property1',value1,'Property2',value2,...) sets properties using one or more name-value pairs. You can specify multiple name-value pairs. Enclose each property name in a quote


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Computed S-parameters, noise figure, OIP3, and group delay values, specified as object. The values are computed over the specified frequency range. By default, this property is empty.

Data Types: function_handle

Capacitance value from source to load of all capacitors in the network, specified as a positive vector in farads. The default value is [0.5330e-8, 0.5330e-8].

Data Types: double

Inductance value from source to load of all inductors in the network, specified as a positive vector in henries. The default value is [2.8318e-6].

Data Types: double

Object name, specified as a 1-by-N character array. This is a read-only property.

Data Types: char

Number of ports, specified as a positive integer. This is a read-only property. By default, the value is 2.

Data Types: double

Object Functions

analyzeAnalyze RFCKT object in frequency domain
calculateCalculate specified parameters for rfckt objects or rfdata objects
circleDraw circles on Smith Chart
extractExtract specified network parameters from rfckt object or data object
listformatList valid formats for specified circuit object parameter
listparamList valid parameters for specified circuit object
loglogPlot specified circuit object parameters using log-log scale
plotPlot circuit object parameters on X-Y plane
plotyyPlot parameters of RF circuit or RF data on X-Y plane with two Y-axes
getopDisplay operating conditions
polarPlot specified object parameters on polar coordinates
semilogxPlot RF circuit object parameters using log scale for x-axis
semilogyPlot RF circuit object parameters using log scale for y-axis
smithPlot circuit object parameters on Smith chart
writeWrite RF data from circuit or data object to file
getz0Calculate characteristic impedance of RFCKT transmission line object
readRead RF data from file to new or existing circuit or data object
restoreRestore data to original frequencies
getopDisplay operating conditions
groupdelayGroup delay of S-parameter object or RF filter object or RF Toolbox circuit object


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Create a LC lowpass pi Filter using rfckt.lclowpasspi.

filter = rfckt.lclowpasspi('C',[1e-12 4e-12],'L',[2e-9 2.5e-9])
filter = 
   rfckt.lclowpasspi with properties:

                 L: [2x1 double]
                 C: [2x1 double]
             nPort: 2
    AnalyzedResult: []
              Name: 'LC Lowpass Pi'


[1] Ludwig, R. and P. Bretchko, RF Circuit Design: Theory and Applications, Prentice-Hall, 2000.

[2] Zverev, A.I., Handbook of Filter Synthesis, John Wiley & Sons, 1967.

Introduced before R2006a