modulator

R2026b

Modulator object

Description

Use the modulator object to create a modulator element. A modulator is a 2-port RF circuit object. You can use this element in the rfbudget object and the circuit object.

Creation

Syntax

mod = modulator

mod = modulator(Name=Value)

Description

mod = modulator creates a modulator object, mod, with default property values.

mod = modulator(Name=Value) creates a modulator object with additional properties specified by one or more name-value arguments. Properties not specified retain their default values.

Properties

Name — Name of modulator

'Modulator' (default) | character vector

Name of modulator, specified as the comma-separated pair consisting of 'Name' and a character vector. All names must be valid MATLAB^® variable names.

Example: Name='mod'

Model — Modulator model

'poly' (default) | 'rfsys'

Modulator model, specified as one of the following:

• 'poly' — Cubic polynomial model. (since R2026b)

• 'rfsys' — RF system data model. This value is automatically set when you create a modulator object using system data from a CSV file or using the rfSystemParameters object, rfPartSelector object, or RF Part Catalog app. (since R2026b)

ConverterType — Modulator converter type

'Up' (default) | 'Down'

Since R2026b

Modulator converter type, specified as one of the following:

• 'Up' — Up converter

• 'Down' — Down converter

Example: ConverterType='Down'

Sideband — Sideband of modulator

'upper' (default) | 'lower'

Since R2026a

Sideband of a modulator, specified as either:

• 'upper' — RF carrier frequency is higher than local oscillator frequency.

• 'lower' — RF carrier frequency is lower than local oscillator frequency.

This table summarizes the modulator operations when Sideband is set.

Input/Output	ConverterType	Sideband	Operation
RF/IF	'Down'	'lower'	IF = LO - RF
		'upper'	IF = RF - LO
IF/RF	'Up'	'lower'	RF = LO - IF
		'upper'	RF = LO + IF

Example: Sideband='upper'

Gain — Available power gain

0 (default) | nonnegative scalar

Available power gain, specified as a nonnegative scalar in dB.

Example: Gain=10

NF — Noise figure

0 (default) | real finite nonnegative scalar

Noise figure, specified as a real finite nonnegative scalar in dB.

Example: NF=10

IIP2 — Second-order input-referred intercept point

inf (default) | real positive number

Since R2026a

Second-order input-referred intercept point, specified as a real positive number in dBm.

Example: IIP2=8

IIP3 — Third-order input-referred intercept point

inf (default) | real positive number

Since R2026a

Third-order input-referred intercept point, specified as a real positive number in dBm.

Example: IIP3=10

IP1dB — Input 1 dB compression point

inf (default) | real positive number

Since R2026a

Input 1 dB compression point, specified as a real positive number in dBm.

Example: IP1dB=20

IPsat — input saturation point

inf (default) | real positive number

Since R2026a

Input saturation point, specified as a positive real number in dBm.

Example: IPsat=20

LO — Local oscillator frequency

1e9 (default) | real finite positive scalar

Local oscillator frequency, specified as a real finite positive scalar in Hz.

Example: LO=2e9

FileName — Name of two-port Touchstone file

string scalar | character vector

Name of the two-port Touchstone file that contains modulator data, specified as a string scalar or character vector.

Example: FileName='default.s2p'

SystemData — Modulator system data

rfSystemParameter object

Since R2026a

Modulator system data, specified as an rfSystemParameters object.

Example: SystemData=rfSystemParameters('Mod_model.csv')

ImageReject — Ideal image reject filtering

true or 1 (default) | false or 0

Ideal image reject filtering at the input of the modulator, specified as a numeric or logical 1 (true) or 0 (false). Setting this property to false or 0 might affect harmonic balance results.

Example: ImageReject=1

Example: ImageReject=true

ChannelSelect — Ideal channel select filtering

true or 1 (default) | false or 0

Ideal channel select filtering at the output of the modulator, specified as a numeric or logical 1 (true) or 0 (false). Setting this property to false or 0 might affect harmonic balance results.

Example: ChannelSelect=1

Example: ChannelSelect=false

Zin — Input impedance

50 (default) | positive real part finite scalar

Input impedance, specified as a positive real part finite scalar in ohms. You can also use a complex value with a positive real part.

Example: Zin=40

Zout — Output impedance

50 (default) | positive real part finite scalar

Output impedance, specified as a scalar in ohms. You can also use a complex value with a positive real part.

Example: Zout=40

NumPorts — Number of ports

2 (default) | scalar integer

Number of ports, specified as a scalar integer. This property is read-only.

Terminals — Names of port terminals

{'p1+' 'p2+' 'p1-' 'p2-'} (default) | cell vector

Names of port terminals, specified as a cell vector. This property is read-only.

Object Functions

clone

Create copy of existing circuit element or circuit object

Examples

Modulator Element

Create a downconverter modulator with a local oscillator (LO) frequency of 100 MHz.

m = modulator(ConverterType='Down',LO=100e6)

m = 
  modulator: Modulator element

             Name: 'Modulator'
    ConverterType: 'Down'
               LO: 100000000
             Gain: 0
              Zin: 50
             Zout: 50
               NF: 0
             IIP2: Inf
             IIP3: Inf
            IP1dB: Inf
            IPsat: Inf
            OPsat: Inf
      ImageReject: 1
    ChannelSelect: 1

Build Modulator Circuit

Create a modulator object with a gain of 4 dB and local oscillator (LO) frequency of 2 GHz. Create another modulator object has an output third-order intercept (OIP3) of 13 dBm.

mod1 = modulator(Gain=4,LO=2e9);
mod2 = modulator(OIP3=13);

Build a two-port circuit using the modulators.

c = circuit([mod1 mod2])

c = 
  circuit: Circuit element

    ElementNames: {'Modulator'  'Modulator_1'}
        Elements: [1×2 modulator]
           Nodes: [0 1 2 3]
            Name: 'unnamed'

RF Budget Analysis of Series of RF Elements

Create an amplifier with a gain of 4 dB.

a = amplifier(Gain=4);

Create a modulator with an IIP3 of 13 dBm.

m = modulator(IIP3=13);

Create an N-port element using passive.s2p.

n = nport('passive.s2p');

Create an RF element with a gain of 10 dB.

r = rfelement(Gain=10);

Calculate the RF budget of a series of RF elements at an input frequency of 2.1 GHz, an available input power of –30 dBm, and a bandwidth of 10 MHz.

b = rfbudget([a m r n],2.1e9,-30,10e6)

b = 
  rfbudget with properties:

               Elements: [1x4 rf.internal.rfbudget.Element]
         InputFrequency: 2.1 GHz
    AvailableInputPower: -30 dBm
        SignalBandwidth:  10 MHz
                 Solver: Friis      
             AutoUpdate: true

   Analysis Results
        OutputFrequency: (GHz) [  2.1    3.1    3.1     3.1]
            OutputPower: (dBm) [  -26    -26    -16   -20.6]
         TransducerGain: (dB)  [    4      4     14     9.4]
                     NF: (dB)  [    0      0      0  0.1391]
                   IIP3: (dBm) [  Inf      9      9       9]
                   OIP3: (dBm) [  Inf     13     23    18.4]
                    SNR: (dB)  [73.98  73.98  73.98   73.84]

Type the show command at the command window to display the analysis in the RF Budget Analyzer app.

show(b)

Version History

Introduced in R2017a

R2026b: Model property no longer supports specifying converter type

Starting in R2026b, the Model property of the modulator and mixerIMT objects no longer specifies the converter type. Use the new ConverterType property to set mixer configuration to 'Up' or 'Down'.

When you run code generated prior to R2026b that used the Model property to specify the converter type, the code generates a warning. To address this, replace Model with ConverterType as shown in this table.

Before R2026b	R2026b Onward
Model='mod'	ConverterType='Up'
Model='demod'	ConverterType='Down'

R2026a: Model modulator using IIP2, IIP3, IP1dB, and IPsat

You can now specify IIP2, IIP3, IP1dB, and IPsat to model an modulator object.

R2026a: Model modulator sidebands

Use the new Sideband property to model modulator sidebands.

R2026a: Model modulator using RF system data

Use the new SystemData property to model a modulator object.

R2026a: Specify input second and third order nonlinearities

Starting in R2026a, the OIP2 and OIP3 properties are replaced with the new IIP2 and IIP3 properties. Use the new properties to specify input second and third order nonlinearities.

When executing code with the modulator object from earlier releases with OIP2 or OIP3, the software will replace these with IIP2 and IIP3 properties, respectively

R2024b: Specify type of conversion using Model property

Use the new Model property in the modulator object to specify the type of conversion as modulation or demodulation.

R2024b: ConverterType property will be removed in future release

The ConverterType property of the modulator object will be removed in a future release. Use the new Model property instead.

When executing code with the modulator object that use the ConverterType property, the software will replace this property with the new Model property.

R2023b: Recommended over rfckt.mixer

modulator is recommend over rfckt.mixer. rfdata.ip3, rfdata.power, and rfdata.nf because it enables you to:

• Create a two-port modulator element.

• Specify third-order intercept points.

• Specify the noise figure value.

• Build a circuit object with a modulator element.

• Model a modulator in an RF chain created using an rfbudget object or the RF Budget Analyzer app.

• Export the modulator element to RF Blockset™ or to rfsystem for circuit envelope or idealized baseband analysis.