Documentation

rfckt.seriesrlc

Series RLC component

Description

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.

Creation

Description

example

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

Properties

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Computed S-parameters, noise figure, OIP3, and group delay values, specified as rfdata.data 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

 analyze Analyze RFCKT object in frequency domain calculate Calculate specified parameters for rfckt objects or rfdata objects extract Extract specified network parameters from rfckt object or data object plotyy Plot specified parameters on X-Y plane with Y-axes on both left and right sides circle Draw circles on Smith Chart listformat List valid formats for specified circuit object parameter listparam List valid parameters for specified circuit object loglog Plot specified circuit object parameters using log-log scale plot Plot specified circuit object parameters on X-Y plane polar Plot specified object parameters on polar coordinates semilogx Plot specified circuit object parameters using log scale for x-axis semilogy Plot specified circuit object parameters using log scale for y-axis smith Plot specified circuit object parameters on Smith chart write Write RF data from circuit or data object to file

Examples

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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);
analyze(h,logspace(4,8,1000));
plot(h,'s21','dB')
ax = gca;
ax.XScale = 'log';

The example then plots the phase, in degrees:

figure
plot(h,'s21','angle')
ax = gca;
ax.XScale = 'log';

Algorithms

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

$Z=\frac{-LC{\omega }^{2}+jRC\omega +1}{jC\omega }$

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.

References

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