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Series RLC component


Use the seriesrlc class to represent a component as a resistor, inductor, and capacitor connected in series.

The series RLC network object is a 2-port network as shown in the following circuit diagram.



h = rfckt.seriesrlc
h = rfckt.seriesrlc('R',Rvalue,'L',Lvalue,'C',Cvalue)



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 circuit object in frequency domain
calculateCalculate specified parameters for circuit object
circleDraw circles on Smith chart
extractExtract array of network parameters from 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 specified circuit object parameters on X-Y plane
plotyyPlot specified object parameters with y-axes on both left and right sides
polarPlot specified circuit object parameters on polar coordinates
semilogxPlot specified circuit object parameters using log scale for x-axis
semilogyPlot specified circuit object parameters using log scale for y-axis
smithPlot specified circuit object parameters on Smith chart
writeWrite RF data from circuit or data object to file


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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.

Introduced in R2009a

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