circuit

Circuit object

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

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: [1×2 rf.internal.circuit.RLC]
           Nodes: [1 2 3]
            Name: 'new_circuit1'
       Terminals: {'t1'  't2'}

Create Circuit with Two Parallel Elements

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: [1×2 rf.internal.circuit.RLC]
           Nodes: [1 2]
            Name: 'new_circuit'

Calculate S-Parameters of Circuit

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)

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.