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Series RLC component


Use the rfckt.seriesrlc object to create a two-port series RLC component as shown in this figure.

2-port series RLC network


seriesRLC is recommended over rfckt.seriesrlc because it enables you to:

  • Create a two-port series RLC element.

  • Build a circuit object with a series RLC element.

  • Model a two-port series RLC element in an RF chain created using an rfbudget object or the RF Budget Analyzer app, and then export this element to RF Blockset™ or to rfsystem System object™ for circuit envelope analysis.

(since R2023b)




h = rfckt.seriesrlc returns a series RLC network object whose properties all have their default values. The default object is equivalent to a pass-through 2-port network, i.e., the resistor, inductor, and capacitor are each replaced by a short circuit.

h = rfckt.seriesrlc('R',Rvalue,'L',Lvalue,'C',Cvalue) 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. Analyzed Result is a read-only property. For more information refer, Algorithms.

Data Types: function_handle

Resistance value, specified as a positive scalar in ohms. The default value is 0.

Data Types: double

Capacitance value, specified as a positive scalar in farads. The default value is 'Inf'.

Data Types: double

Inductance value, specified as a positive scalar in henries. The default value is 0.

Data Types: double

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

Data Types: char

Number of ports, specified as a positive integer. nportt is a read-only property. The default 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 xy-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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This example creates a series LC resonator and examines its frequency response. It first creates the circuit object and then uses the analyze method to calculate its frequency response. Finally, it plots the results - first, the magnitude in decibels (dB):

h = rfckt.seriesrlc('L',4.7e-5,'C',2.2e-10);
ax = gca;
ax.XScale = 'log';

The example then plots the phase, in degrees:

ax = gca;
ax.XScale = 'log';


The analyze method computes the S-parameters of the AnalyzedResult property using the data stored in the rfckt.seriesrlc object properties by first calculating the ABCD-parameters for the circuit, and then converting the ABCD-parameters to S-parameters using the abcd2s function. For this circuit, A = 1, B = Z, C = 0, and D = 1, where


and ω = 2πf.

The analyze method uses the S-parameters to calculate the group delay values at the frequencies specified in the analyze input argument freq, as described in the analyze reference page.


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

Version History

Introduced in R2009a