rfckt.amplifier

RF Amplifier

Description

Use the rfckt.amplifier object to represent RF amplifiers that are characterized by network parameters, noise data, and nonlinearity data

Use the read object function to read the amplifier data from a data file in one of the following formats:

• Touchstone

• Agilent^® P2D

• Agilent S2D

• AMP

Note

If you set NonLinearData using rfdata.ip3 or rfdata.power, then the property is converted from scalar OIP3 format to the format of rfdata.ip3 or rfdata.power.

Creation

Syntax

h = rfckt.amplifier

h = rfckt.amplifier('Property1',value1,'Property2',value2,...)

Description

h = rfckt.amplifier returns an amplifier circuit object whose properties all have their default values.

h = rfckt.amplifier('Property1',value1,'Property2',value2,...) sets properties using one or more name-value pairs. For example, rfckt.amplifier ('IntType','Cubic') creates an RF amplifier circuit that uses cubic interpolation. You can specify multiple name-value pairs. Enclose each property name in a quote.

Properties

AnalyzedResult — Computed S-parameters, noise figure, OIP3, and group delay values

rfdata.data object

This property is read-only.

Computed S-parameters, noise figure, OIP3, and group delay values, specified as an rfdata.data object. For more information refer, .Algorithms.

Data Types: function_handle

IntpType — Interpolation method used in rfckt.amplifier

'Linear' (default) | 'Spline' | 'Cubic'

Interpolation method specified one of the following values:

Method	Description
Linear	Linear interpolation
Spline	Cubic spline interpolation
Cubic	Piecewise cubic Hermite interpolation

Data Types: char

Name — Name of amplifier object

1-by-N character array

This property is read-only.

Name of amplifier object.

Data Types: char

NetworkData — Network parameter data

rfdata.network object

Network parameter data.

Data Types: function_handle

NoiseData — Noise information

scalar noise figure in decibels | rfdata.noise object | rfdata.nf object

Noise information, specified as one of the following:

• Scalar noise figure in dB

• rfdata.noise object

• rfdata.nf object

Data Types: double | function_handle

'NonlinearityData' — Nonlinearity information

scalar OIP3 in dB | rfdata.power object | rfdata.ip3 object

Noise information, specified as one of the following:

• Scalar OIP3 in dB

• rfdata.power object

• rfdata.ip3 object

Data Types: double | function_handle

nport — Number of ports

positive integer

This property is read-only.

Number of ports. 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
plotyy	Plot specified parameters on X-Y plane with Y-axes on both left and right sides
circle	Draw circles on Smith Chart
extract	Extract specified network parameters from rfckt object or data object

Examples

Create RF Circuit Amplifier

Create an Amplifier using rfckt.amplifier object.

amp = rfckt.amplifier('IntpType','cubic')

amp = 
   rfckt.amplifier with properties:

         NoiseData: [1x1 rfdata.noise]
     NonlinearData: [1x1 rfdata.power]
          IntpType: 'Cubic'
       NetworkData: [1x1 rfdata.network]
             nPort: 2
    AnalyzedResult: [1x1 rfdata.data]
              Name: 'Amplifier'

Algorithms

The analyze function computes the AnalyzedResult property using the data stored in the rfckt.amplifier object properties as follows:

• The analyze function uses the data stored in the NoiseData property of the rfckt.amplifier object to calculate the noise figure.

• The analyze function uses the data stored in the NonlinearData property of the rfckt.amplifier object to calculate OIP3.

  If power data exists in the NonlinearData property, the block extracts the AM/AM and AM/PM nonlinearities from the power data.

  If the NonlinearData property contains only IP3 data, the method computes and adds the nonlinearity by:

  1. Using the third-order input intercept point value in dBm to compute the factor, f, that scales the input signal before the amplifier object applies the nonlinearity:

     $$F_{AM/AM}(u)=u-\frac{u^3}{3}$$

  2. Computing the scaled input signal by multiplying the amplifier input signal by f.

  3. Limiting the scaled input signal to a maximum value of 1.

  4. Applying an AM/AM conversion to the amplifier gain, according to the following cubic polynomial equation:

     $$F_{AM/AM}(u)=u-\frac{u^3}{3}$$

     where u is the magnitude of the scaled input signal, which is a unitless normalized input voltage.

• The analyze function uses the data stored in the 'NetworkData' property of the rfckt.amplifier object to calculate the group delay values of the amplifier at the frequencies specified in freq, as described in the analyze function reference page.

• The analyze function uses the data stored in the NetworkData property of the rfckt.amplifier object to calculate the S-parameter values of the amplifier at the frequencies specified in freq. If the 'NetworkData' property contains network Y-parameters or Z-parameters, the analyze function first converts the parameters to S-parameters. Using the interpolation method you specify with the IntpType property, the analyze method interpolates the S-parameter values to determine their values at the specified frequencies.

  Specifically, the analyze function orders the S-parameters according to the ascending order of their frequencies, f_n. It then interpolates the S-parameters, using the MATLAB^® interp1 function. For example, the curve in the following diagram illustrates the result of interpolating the S₁₁ parameters at five different frequencies.

  

  For more information, see “One-Dimensional Interpolation” and the interp1 reference page.

  As shown in the preceding diagram, the analyze function uses the parameter values at f_min, the minimum input frequency, for all frequencies smaller than f_min. It uses the parameters values at f_max, the maximum input frequency, for all frequencies greater than f_max. In both cases, the results may not be accurate, so you need to specify network parameter values over a range of frequencies that is wide enough to account for the amplifier behavior.

References

[1] EIA/IBIS Open Forum. Touchstone File Format Specification, Rev. 1.1, 2002 (https://ibis.org/connector/touchstone_spec11.pdf).