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AMP File Data Sections

Overview

The AMP data file describes a single nonlinear device. Its format can contain the following types of data:

  • S, Y, or Z network parameters

  • Noise parameters

  • Noise figure data

  • Power data

  • IP3 data

An AMP file must contain either power data or network parameter data to be valid. To accommodate analysis at more than one frequency, the file can contain more than one section of power data. Noise data, noise figure data, and IP3 data are optional.

    Note:   If the file contains both network parameter data and power data, RF Toolbox™ software checks the data for consistency. If the amplifier gain computed from the network parameters is not consistent with the gain computed from the power data, a warning appears. For more information, see Inconsistent Data Sections.

Two AMP files, samplepa1.amp and default.ampdefault.amp, ship with the toolbox to show the AMP format. They describe a nonlinear 2-port amplifier with noise. See Model a Cascaded RF Network for an example that shows how to use an AMP file.

For information on specifying data in an AMP file, see AMP File Data Sections. For information about adding comments to an AMP file, see Denoting Comments.

Denoting Comments

An asterisk (*) or an exclamation point (!) precedes a comment that appears on a separate line.

A semicolon (;) precedes a comment that appears following data on the same line.

Data Sections

Each kind of data resides in its own section. Each section consists of a two-line header followed by lines of numeric data. Numeric values can be in any valid MATLAB® format.

A new header indicates the end of the previous section. The data sections can appear in any order in the file.

    Note:   In the data section descriptions, brackets ([]) indicate optional data or characters. All values are case insensitive.

S, Y, or Z Network Parameters

Header Line 1

The first line of the header has the format

Keyword [Parameter] [R[REF][=]value]

Keyword indicates the type of network parameter. Its value can be S[PARAMETERS], Y[PARAMETERS], or Z[PARAMETERS]. Parameter indicates the form of the data. Its value can be MA, DB, or RI. The default for S-parameters is MA. The default for Y- and Z-parameters is RI. R[REF][=]value is the reference impedance. The default reference impedance is 50 ohms.

The following table explains the meaning of the allowable Parameter values.

Parameter

Description

MA

Data is given in (magnitude, angle) pairs with angle in degrees (default for S-parameters).

DB

Data is given in (dB-magnitude, angle) pairs with angle in degrees.

RI

Data is given in (real, imaginary) pairs (default for Y- and Z-parameters).

This example of a first line indicates that the section contains S-parameter data given in (real, imaginary) pairs, and that the reference impedance is 50 ohms.

S RI R 50

Header Line 2

The second line of the header has the format

Independent_variable Units

The data in a section is a function of the Independent_variable. Currently, for S-, Y-, and Z-parameters, the value of Independent_variable is always F[REQ]. Units indicates the default units of the frequency data. It can be GHz, MHz, or KHz. You must specify Units, but you can override this default on any given line of data.

This example of a second line indicates that the default units for frequency data is GHz.

FREQ GHZ

Data

The data that follows the header typically consists of nine columns.

The first column contains the frequency points where network parameters are measured. They can appear in any order. If the frequency is given in units other than those you specified as the default, you must follow the value with the appropriate units; there should be no intervening spaces. For example,

FREQ GHZ
1000MHZ  ...
2000MHZ  ...
3000MHZ  ...

Columns two though nine contain 2-port network parameters in the order N11, N21, N12, N22. Similar to the Touchstone format, each Nnn corresponds to two consecutive columns of data in the chosen form: MA, DB, or RI. The data can be in any valid MATLAB format.

This example is derived from the file default.amp. A comment line explains the column arrangement of the data where re indicates real and im indicates imaginary.

S RI R 50
FREQ GHZ 
* FREQ     reS11      imS11      reS21      imS21    reS12     imS12      reS22      imS22
  1.00  -0.724725  -0.481324  -0.685727  1.782660  0.000000  0.000000  -0.074122  -0.321568
  1.01  -0.731774  -0.471453  -0.655990  1.798041  0.001399  0.000463  -0.076091  -0.319025
  1.02  -0.738760  -0.461585  -0.626185  1.813092  0.002733  0.000887  -0.077999  -0.316488

Noise Parameters

Header Line 1

The first line of the header has the format

Keyword

Keyword must be NOI[SE].

Header Line 2

The second line of the header has the format

Variable Units

Variable must be F[REQ]. Units indicates the default units of the frequency data. It can be GHz, MHz, or KHz. You can override this default on any given line of data. This example of a second line indicates that frequency data is assumed to be in GHz, unless other units are specified.

FREQ GHz

Data

The data that follows the header must consist of five columns.

The first column contains the frequency points at which noise parameters were measured. The frequency points can appear in any order. If the frequency is given in units other than those you specified as the default, you must follow the value with the appropriate units; there should be no intervening spaces. For example,

NOI
FREQ GHZ
1000MHZ  ...
2000MHZ  ...
3        ...
4        ...
5        ...

Columns two through five contain, in order,

  • Minimum noise figure in decibels

  • Magnitude of the source reflection coefficient to realize minimum noise figure

  • Phase in degrees of the source reflection coefficient

  • Effective noise resistance normalized to the reference impedance of the network parameters

This example is taken from the file default.amp. A comment line explains the column arrangement of the data.

NOI RN
FREQ GHz
* Freq  Fmin(dB)  GammmaOpt(MA:Mag) GammmaOpt(MA:Ang) RN/Zo
  1.90  10.200000 1.234000         -78.400000         0.240000
  1.93  12.300000 1.235000         -68.600000         0.340000
  2.06  13.100000 1.254000         -56.700000         0.440000
  2.08  13.500000 1.534000         -52.800000         0.540000
  2.10  13.900000 1.263000         -44.400000         0.640000

Noise Figure Data

The AMP file format supports the use of frequency-dependent noise figure (NF) data.

Header Line 1

The first line of the header has the format

Keyword [Units]

For noise figure data, Keyword must be NF. The optional Units field indicates the default units of the NF data. Its value must be dB, i.e., data must be given in decibels.

This example of a first line indicates that the section contains NF data, which is assumed to be in decibels.

NF

Header Line 2

The second line of the header has the format

Variable Units

Variable must be F[REQ]. Units indicates the default units of the frequency data. It can be GHz, MHz, or KHz. This example of a second line indicates that frequency data is assumed to be in GHz.

FREQ GHz

Data

The data that follows the header typically consists of two columns.

The first column contains the frequency points at which the NF data are measured. Frequency points can appear in any order. For example,

NF 
FREQ MHz
2090  ...
2180  ...
2270  ...

Column two contains the corresponding NF data in decibels.

This example is derived from the file samplepa1.amp.

NF dB
FREQ GHz
1.900   10.3963213
2.000   12.8797965
2.100   14.0611765
2.200   13.2556751
2.300   12.9498642
2.400   13.3244309
2.500   12.7545104

    Note:   If your noise figure data consists of a single scalar value with no associated frequency, that same value is used for all frequencies. Enter the value in column 1 of the line following header line 2. You must include the second line of the header, but it is ignored.

Power Data

An AMP file describes power data as input power-dependent output power.

Header Line 1

The first line of the header has the format

Keyword [Units]

For power data, Keyword must be POUT, indicating that this section contains power data. Because output power is complex, Units indicates the default units of the magnitude of the output power data. It can be dBW, dBm, mW, or W. The default is W. You can override this default on any given line of data.

The following table explains the meaning of the allowable Units values.

Allowable Power Data Units

Units

Description

dBW

Decibels referenced to one watt

dBm

Decibels referenced to one milliwatt

mW

Milliwatts

W

Watts

This example of a first line indicates that the section contains output power data whose magnitude is assumed to be in decibels referenced to one milliwatt, unless other units are specified.

POUT dBm

Header Line 2

The second line of the header has the format

Keyword [Units] FREQ[=]value

Keyword must be PIN. Units indicates the default units of the input power data. See Allowable Power Data Units for a complete list of valid values. The default is W. You can override this default on any given line of data. FREQ[=]value is the frequency point at which the power is measured. The units of the frequency point must be specified explicitly using the abbreviations GHz, MHz, kHz, or Hz.

This example of a second line indicates that the section contains input power data that is assumed to be in decibels referenced to one milliwatt, unless other units are specified. It also indicates that the power data was measured at a frequency of 2.1E+009 Hz.

PIN dBm FREQ=2.1E+009Hz

Data

The data that follows the header typically consists of three columns:

  • The first column contains input power data. The data can appear in any order.

  • The second column contains the corresponding output power magnitude.

  • The third column contains the output phase shift in degrees.

      Note:   RF Toolbox software does not use the phase data directly. SimRF™ blocks use this data in conjunction with RF Toolbox software to create the AM/PM conversion table for the Equivalent Baseband library General Amplifier and General Mixer blocks.

If all phases are zero, you can omit the third column. If all phases are zero or omitted, the toolbox assumes that the small signal phase from the network parameter section of the file (180*angle(S21(f))/pi) is the phase for all power levels.

In contrast, if one or more phases in the power data section are nonzero, the toolbox interpolates and extrapolates the data to determine the phase at all power levels. The small signal phase (180*angle(S21(f))/pi) from the network parameter section is ignored.

Inconsistency between the power data and network parameter sections of the file may cause incorrect results. To avoid this outcome, verify that the following criteria must is met:

  • The lowest input power value for which power data exists falls in the small signal (linear) region.

  • In the power table for each frequency point f, the power gain and phase at the lowest input power value are equal to 20*log10(abs(S21(f))) and 180*angle(S21(f))/pi, respectively, in the network parameter section.

If the power is given in units other than those you specified as the default, you must follow the value with the appropriate units. There should be no intervening spaces.

This example is derived from the file default.amp. A comment line explains the column arrangement of the data.

POUT dbm
PIN dBm FREQ = 2.10GHz
* Pin     Pout            Phase(degrees)
  0.0     19.28           0.0
  1.0     20.27           0.0
  2.0     21.26           0.0

    Note:   The file can contain more than one section of power data, with each section corresponding to a different frequency value. When you analyze data from a file with multiple power data sections, power data is taken from the frequency point that is closest to the analysis frequency.

IP3 Data

An AMP file can include frequency-dependent, third-order input (IIP3) or output (OIP3) intercept points.

Header Line 1

The first line of the header has the format

Keyword [Units]

For IP3 data, Keyword can be either IIP3 or OIP3, indicating that this section contains input IP3 data or output IP3 data. Units indicates the default units of the IP3 data. Valid values are dBW, dBm, mW, and W. The default is W. See Allowable Power Data Units for an explanation of the allowable Units values.

This example of a first line indicates that the section contains input IP3 data which is assumed to be in decibels referenced to one milliwatt.

IIP3 dBm

Header Line 2

The second line of the header has the format

Variable Units

Variable must be FREQ. Units indicates the default units of the frequency data. Valid values are GHz, MHz, and KHz. This example of a second line indicates that frequency data is assumed to be in GHz.

FREQ GHz

Data

The data that follows the header typically consists of two columns.

The first column contains the frequency points at which the IP3 parameters are measured. Frequency points can appear in any order.

OIP3 
FREQ GHz
2.010  ...
2.020  ...
2.030  ...

Column two contains the corresponding IP3 data.

This example is derived from the file samplepa1.amp.

OIP3 dBm
FREQ GHz
2.100   38.8730377

    Note:   If your IP3 data consists of a single scalar value with no associated frequency, then that same value is used for all frequencies. Enter the value in column 1 of the line following header line 2. You must include the second line of the header, but the application ignores it.

Inconsistent Data Sections

If an AMP file contains both network parameter data and power data, RF Toolbox software checks the data for consistency.

The toolbox compares the small-signal amplifier gain defined by the network parameters, S21, and by the power data, Pout – Pin. The discrepancy between the two is computed in dBm using the following equation:

wherefP is the lowest frequency for which power data is specified.

The discrepancy is shown in the following graph.

If ΔP is more than 0.4 dB, a warning appears. Large discrepancies may indicate measurement errors that require resolution.

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