Amplifier

Complex baseband model of amplifier with noise and nonlinearities

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Libraries:
RF Blockset / Idealized Baseband

Description

The Amplifier block generates a complex baseband model of an amplifier with thermal noise. This block provides four nonlinearity models and three options to specify noise representation.

Examples

Idealized Baseband Amplifier with Nonlinearity and Noise

The example shows how to use the idealized baseband library Amplifier block to amplify a signal with nonlinearity and noise. The Amplifier uses the Cubic Polynomial model with a Linear power gain of 10 dB, an Input IP3 nonlinearity of 30 dBm, and a Noise figure of 3 dB.

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Ports

Input

Port_1 — Input baseband signal

scalar | column | matrix (since R2026a)

Input baseband signal, specified as a scalar, column, or matrix of a real or complex values.

Data Types: double | single

Output

Port_1 — Output baseband signal

scalar | column | matrix (since R2026a)

Output baseband signal, returned as a scalar, column, or matrix of a real or complex values. The output port mimics the properties of the input port. For example, if the input baseband signal is specified as a real scalar with data type double, then the output baseband signal is also specified as a real signal with data type double.

Data Types: double | single

Parameters

Main Tab

Model — Amplifier nonlinearity model

poly (default) | cubic | ampm | modified-rapp | saleh

Specify the amplifier nonlinearity model as one of the following:

• poly — Use this model to concurrently model multiple nonlinear parameters within the idealized amplifier architecture. (since R2026a)

• cubic — Use this model to determine the linear coefficient of a third‑order polynomial and either IP3, P1dB, or Psat to determine the third‑order coefficient. The cubic polynomial model uses linear power gain to determine the values.

• ampm — Use this model to apply an AM/AM–AM/PM lookup table for computing the amplifier power characteristics.

• modified-rapp — Use this model to apply a normalized transfer function to compute the amplifier power characteristics.

• saleh — Use this model to apply a normalized transfer function based on the Saleh formulation to compute the amplifier power characteristics.

For more information, see Nonlinearity Models in Idealized Amplifier Block.

Linear power gain (dB) — Linear gain of amplifier

0 (default) | real scalar

Linear gain, specified as a scalar in dB.

Type of Non-Linearity — Third - order nonlinearity type

OIP3 (default) | IIP3 | IP1dB | OP1dB | IPsat | OPsat

Third order nonlinearity type, specified as IIP3, OIP3, IP1dB, OP1dB, IPsat, or OPsat.

IIP3 (dBm) — Input third-order intercept point

Inf (default) | real positive number

Input third-order intercept point, specified as a real positive number in dBm.

Dependencies

To enable this parameter, set Model to cubic and Type of Non-Linearity to IIP3.

OIP3 (dBm) — Output third-order intercept point

Inf (default) | real positive number

Output third-order intercept point, specified as a real positive number in dBm.

Dependencies

To enable this parameter, set either one of these:

• Model to cubic and Type of Non-Linearity to OIP3.

• Model to poly

IP1dB (dBm) — Input 1 dB compression point

Inf (default) | real positive number

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

Dependencies

To enable this parameter, set Model to cubic and Type of Non-Linearity to IP1dB.

OP1dB (dBm) — Output 1 dB compression point

Inf (default) | real positive number

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

Dependencies

To enable this parameter, set either one of these:

• Model to cubic and Type of Non-Linearity to OP1dB.

• Model to poly

IPsat (dBm) — Input saturation point

Inf (default) | real positive number

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

Dependencies

To enable this parameter, set either one of these:

• Model to cubic and Type of Non-Linearity to IPsat.

• Model to poly

OPsat (dBm) — Output saturation point

Inf (default) | real positive number

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

Dependencies

To enable this parameter, set either one of these:

• Model to cubic and Type of Non-Linearity to OPsat.

• Model to poly

Simulate using — Specify type of simulation to run

Code generation (default) | Interpreted execution

• Code generation – Simulate model using generated C code. The first time you run a simulation, Simulink^® generates C code for the block. The C code is reused for subsequent simulations, as long as the model does not change. This option requires additional startup time, but the speed of the subsequent simulations is faster than Interpreted execution.

• Interpreted execution – Simulate model using the MATLAB^® interpreter. This option shortens startup time speed, but the speed of the subsequent simulations is slower than Code generation. In this mode, you can debug the source code of the block.

Plot power characteristics — Plot power characteristics

button (default)

This button plots the power characteristics based on the parameters specified on the Main tab.

For more information, see Plot Power Characteristics.

Lookup table (Pin(dBm), Pout(dBm), deg) — Lookup table

[ -25, 5, -1; -10, 20, -2; 0, 27, 5; 5, 28, 12 ] (default) | M-by-3 real matrix

Table lookup entries specified as a real M-by-3 matrix. This table expresses the model output power dBm level in matrix column 2 and the model phase change in degrees in matrix column 3 as related to the absolute value of the input signal power of matrix column 1 for the AM/AM - AM/PM model. The column 1 input power must increase monotonically.

The interp1 function with the linear method is employed to extrapolate and interpolate the data points specified in the lookup table. Furthermore, for extrapolating input data points that are less than the smallest specified input power value in the lookup table, the AM/AM extrapolation uses a slope of 1 and constant phase value equal to the phase of the smallest input power.

Dependencies

To enable this parameter, set Model to ampm.

Output saturation level (V) — Output saturation level

1 (default) | real positive number

Voltage output saturation level, specified as a real positive number in dBm.

Dependencies

To enable this parameter, set Model to modified-rapp.

Magnitude smoothness factor — Magnitude smoothness factor

2 (default) | real positive number

Magnitude smoothness factor for the modified-rapp amplifier model AM/AM calculations, specified as a positive real number.

Dependencies

To enable this parameter, set Model to modified-rapp.

Phase gain (rad) — Phase gain

-0.45 (default) | real scalar

Phase gain for the modified-rapp amplifier model AM/PM calculations, specified as a real scalar in radians.

Dependencies

To enable this parameter, set Model to modified-rapp.

Phase saturation — Phase saturation

0.88 (default) | real positive number

Phase saturation for the modified-rapp amplifier model AM/PM calculations, specified as a positive real number.

Dependencies

To enable this parameter, set Model to modified-rapp.

Phase smoothness factor — Phase smoothness factor

[3.43, 3.43] (default) | real positive number | two-tuple vector

Phase smoothness factor for the modified-rapp amplifier model AM/PM calculations, specified as a positive real number or two-tuple vector.

Dependencies

To enable this parameter, set Model to modified-rapp.

Input scaling (dB) — Scaling factor for input signal level

0 (default) | nonnegative real number

Scaling factor for input signal level for the saleh amplifier model, specified as a nonnegative real number in dB.

Dependencies

To enable this parameter, set Model to saleh.

AM / AM parameters [alpha beta] — AM/AM conversion parameters

[ 2.1587, 1.1517 ] (default) | two-element vector

AM/AM two-tuple conversion parameters for saleh amplifier model, specified as a two-element vector of nonnegative real numbers.

Dependencies

To enable this parameter, set Model to saleh.

AM / PM parameters [alpha beta] — AM/PM conversion parameters

[ 4.0033, 9.1040 ] (default) | two-element vector

AM/PM two-tuple conversion parameters for saleh amplifier model, specified as a two-element vector of nonnegative real numbers.

Dependencies

To enable this parameter, set Model to saleh.

Output scaling (dB) — Scaling factor for output signal level

0 (default) | nonnegative real number

Scaling factor for output signal level for saleh amplifier model, specified as nonnegative real number in dB.

Dependencies

To enable this parameter, set Model to saleh.

Noise Tab

Include Noise — Add noise to system

off (default) | on

Select this parameter to add system noise to the input signal. Once you select this parameter, the parameters associated with the Noise tab are displayed.

Specify noise type — Noise representation

NF (default) | noise-temperature | noise-factor

Type of noise, specified as one of the following:

• noise-temperature — Noise temperature

• NF — Noise figure

• noise-factor — Noise factor

For more information, see Thermal Noise Simulations in Idealized Amplifier Block.

Dependencies

To enable this parameter, select Include Noise.

Noise temperature (K) — Noise temperature to model noises in amplifier

290 (default) | nonnegative real number

Noise temperature to model noise in the amplifier, specified as a nonnegative real number in degrees (K).

Dependencies

To enable this parameter, select Include Noise and set Specify noise type to noise-temperature.

Noise figure (dB) — Noise figure to model noise in amplifier

10 * log10( 2 ) (default) | nonnegative real number

Noise figure to model noise in the amplifier, specified as a nonnegative real number in dB.

Dependencies

To enable this parameter, select Include Noise and set Specify noise type to NF.

Noise factor — Noise factor to model noise in amplifier

2 (default) | positive integer scalar greater than or equal to 1

Noise factor to model noise in the amplifier, specified as a positive integer scalar greater than or equal to 1.

Dependencies

To enable this parameter, select Include Noise and set Specify noise type to noise-factor.

Seed source — Source of initial seed

auto (default) | user

Source of initial seed used to prepare the Gaussian random number noise generator, specified as one of the following:

• auto — Automatically generate seeds for each amplifier instance using a random number generator. The reset method of the instance has no effect.

• user — Use the value specified in the Seed parameter to initialize the random number generator. The reset method resets the random number generator and uses the value specified in the Seed parameter to initialize it.

Seed — Seed for random number generator

67987 (default) | scalar | row vector (since R2026a)

Seed to initialize the random number generator, specified as either:

• Scalar — Specify the seed value as a scalar to enable all the RF channel have the same Seed value.

• Row vector — Specify the seed value as a row vector to enable different seed for each channel (since R2026a)

Dependencies

To enable this parameter, select the Include Noise parameter and set the the Seed source parameter to user.

References

[1] Razavi, Behzad. “Basic Concepts “ in RF Microelectronics, 2nd edition, Prentice Hall, 2012.

[2] Rapp, C., “Effects of HPA-Nonlinearity on a 4-DPSK/OFDM-Signal for a Digital Sound Broadcasting System.” Proceedings of the Second European Conference on Satellite Communications, Liege, Belgium, Oct. 22-24, 1991, pp. 179-184.

[3] Saleh, A.A.M., “Frequency-independent and frequency-dependent nonlinear models of TWT amplifiers.” IEEE Trans. Communications, vol. COM-29, pp.1715-1720, November 1981.

[4] IEEE 802.11-09/0296r16. “TGad Evaluation Methodology.“ Institute of Electrical and Electronics Engineers.https://www.ieee.org/

[5] Kundert, Ken.“ Accurate and Rapid Measurement of IP₂ and IP₃,“ The Designer Guide Community, May 22, 2002.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2020a

R2026a: Concurrent modeling of multiple nonlinearities within amplifier architecture

Configure the idealized Amplifier block with the poly model type to concurrently model multiple nonlinear parameters within the idealized amplifier architecture.

R2026a: Multi-channel simulation support in Idealized Baseband environment

The Amplifier block now supports matrix inputs to enable the simulation of multiple independent RF channels concurrently within the Idealized Baseband simulation environment.

R2024b: Parameters of Amplifier block from idealized baseband library have been renamed

The following parameter values in the Amplifier block in the idealized baseband library have been renamed:

Parameter	Values before R2024b	Values since R2024b
Model	Cubic polynomial	cubic
	AM/AM - AM/PM	ampm
	Modified Rapp	modified-rapp
	Saleh	saleh
Specify noise type	Noise figure	NF
	Noise temperature	noise-temperature
	Noise factor	noise-factor
Seed source	Auto	auto
	User specified	user

The following default values in the Amplifier block in the idealized baseband library have been changed:

Parameter	Default Values Before R2024b	Default Values Since R2024b
Type of Non-linearity	IIP3	OIP3
Specify noise type	Noise temperature	NF

When you open a model created before R2024b containing the Amplifier block, the software replaces the parameter names and values as shown in the table.