circuit

Circuit object

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Description

Use circuit object to build a circuit object which can contain elements like resistor, capacitor, and inductor.

Creation

Syntax

cktobj = circuit

cktobj = circuit(cktname)

cktobj = circuit([elem1,...,elemN])

cktobj = circuit([elem1,...,elemN],cktname)

cktobj = circuit(rfb)

cktobj = circuit(rfb,cktname)

Description

cktobj = circuit creates a circuit object cktobj with a default name.

cktobj = circuit(cktname) creates a circuit object cktobj with name of cktname.

cktobj = circuit([elem1,...,elemN]) creates a circuit object cktobj by cascading the specified 2-port elements.

cktobj = circuit([elem1,...,elemN],cktname) creates a cascaded circuit object cktobj with the name, cktname.

cktobj = circuit(rfb) creates a circuit object cktobj by cascading the elements in the RF object, rfb.

cktobj = circuit(rfb,cktname) creates a circuit object cktobj by cascading the elements in the RF object, rfb, using name, cktname.

Input Arguments

`elem1,...,elemN` — 2-port RF elements
character vector

2-port RF elements, specified as character vectors. The possible elements are amplifier, nport, and modulator

`rfb` — RF budget object
object handle

RF budget object, specified as an object handle.

Properties

`Name` — Object Name
`'unnamed'` (default) | character vector

Name of circuit, specified as a character vector. Default name is 'unnamed'. Two circuit elements attached together or belonging to the same circuit cannot have the same name

Data Types: char | string

`Elements` — Heterogeneous array of elements in circuit
`resistor` object | `capacitor` object | `inductor` object | `lcladder` object | `nport` object | `modulator` object | `rffilter` object | `amplifier` object

Heterogeneous array of elements present in the circuit, specified as any one of the following objects: amplifier, resistor, capacitor, inductor, lcladder, nport, modulator, and rffilter objects.

Data Types: char | string

`ElementNames` — Name of elements in the circuit
cell vector

Name of elements in the circuit, specified as a vector of cell vector. The possible elements here are resistor, capacitor, inductor, and circuit.

Data Types: char | string

`Terminals` — Names of terminals in the circuit
cell vector

Names of terminals in the circuit, specified as a cell vector. Use setports or setterminals function to define the terminals. The terminals of the circuit are only displayed once it is defined.

Data Types: char | string

`Ports` — Names of ports in a circuit
character vector

Names of ports in a circuit specified as a character vector. Use setports function to define the ports. The ports of the circuit are only displayed once it is defined.

Data Types: char | string

`Nodes` — List of nodes defined in circuit
vector of integers

List of nodes defined in the circuit, specified as a vector of integers. These nodes are created when a new element is attached to the circuit.

Data Types: double

`ParentPath` — Full path of parent circuit
character vector

Full path of parent circuit, specified as a character vector. This path appears only once the child circuit is added to the parent circuit.

Data Types: char | string

`ParentNodes` — Nodes of parent circuit
vector of integers.

Nodes of parent circuit, specified as a vector of integers. This vector of integers is the same length as the Terminals property. This property is read-only and appears only after the child circuit is added to the parent circuit.

Data Types: double

Object Functions

`sparameters`	Calculate S-parameters for RF data, network, circuit, and matching network objects
`groupdelay`	Group delay of S-parameter object or RF filter object or RF Toolbox circuit object
`add`	Insert circuit element or circuit object into circuit
`delete`	Delete circuit object and decouple its elements
`setports`	Set ports of circuit object
`setterminals`	Set terminals of circuit object
`clone`	Create copy of existing circuit element or circuit object
`richards`	Convert lumped element circuit to distributed element circuit using Richards' transformation

Examples

Create Circuit with Elements and Terminals

Open Live Script

Create a circuit called new_circuit. Add a resistor and capacitor to the circuit. Set the terminals and display the results.

hckt = circuit('new_circuit1');
hC1= add(hckt,[1 2],capacitor(3e-9));
hR1 = add(hckt,[2 3],resistor(100));
setterminals (hckt,[1 3]);
disp(hckt)

  circuit: Circuit element

    ElementNames: {'C'  'R'}
        Elements: [1x2 rf.internal.circuit.RLC]
           Nodes: [1 2 3]
            Name: 'new_circuit1'
       Terminals: {'t1'  't2'}

Create Circuit with Two Parallel Elements

Open Live Script

Create a circuit called new_circuit. Add a capacitor and inductor parallel to the circuit.

hckt = circuit('new_circuit');
hC = add(hckt,[1 2],capacitor(1e-12));
hL = add(hckt,[1 2],inductor(1e-9));
disp(hckt)

  circuit: Circuit element

    ElementNames: {'C'  'L'}
        Elements: [1x2 rf.internal.circuit.RLC]
           Nodes: [1 2]
            Name: 'new_circuit'

Calculate S-Parameters of Circuit

Open Live Script

Create a circuit object. This example uses a four-element circuit.

c = circuit('example_ckt');

Before connecting the elements in a circuit, first use the nport object to create a linear circuit element. The characteristics of the four linear elements are derived from a five-port and one-port Touchstone™ files.

n5 = nport('defaultnew.s5p');
n1 = nport('dipole_antenna.s1p');
n2 = nport('dipole_antenna.s1p');
n3 = nport('dipole_antenna.s1p');

Use the add function to connect the elements of the circuit. First, add the five-port element to the circuit object.

add(c,[1 2 3 4 5],n5)

Add the one-port element n1 to the third terminal of the circuit object.

add(c,[3 0],n1);

Add the one-port element n2 to the fourth terminal of the circuit object.

add(c,[4 0],n2);

Add the one-port element n3 to the fifth terminal of the circuit object.

add(c,[5 0],n3);

Set the ports of the circuit and define the node pairs as [1 2] using the setports function.

setports(c,[1 2]);

Calculate the S-parameters of the circuit.

S = sparameters(c,n5.NetworkData.Frequencies);

Plot the S-parameter data of the circuit using the rfplot function.

rfplot(S)

$Figure contains an axes object. The axes object with xlabel Frequency (GHz), ylabel Magnitude (dB) contains an object of type line. This object represents dB(S_{11}).$

Version History

Introduced in R2013b

R2023b: Recommended over `rfckt.hybrid`, `rfckt.hybridg`, `rfckt.series`, and `rfckt.parallel`

circuit object and add function is recommended over rfckt.hybrid, rfckt.hybridg, rfckt.series, and rfckt.parallel objects because the add function enables you to insert linear and nonlinear elements into a circuit object to create networks of any topology which includes a hybrid, an inverse hybrid, a parallel, and a series connected network.

See Also

resistor | capacitor | inductor | add

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