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.

Two AMP files, `samplepa1.amp` and `default.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.

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

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.

Note

`R[REF][=]value` must be a positive real scalar or vector. If `R[REF][=]value` is a vector, then the vector must be equal to the number of network parameter data points or frequency vector.

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 ```

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

The first line of the header has the format

```Keyword ```

`Keyword` must be `NOI[SE]`.

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.

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 ```

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.

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 ```

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. 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. RF Blockset™ blocks use this data in conjunction with RF Toolbox software to create the AM/PM conversion table for the Equivalent Baseband library General Amplifier (RF Blockset) and General Mixer (RF Blockset) 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.

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`.

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 ```

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:

`$\Delta P={S}_{21}\left({f}_{P}\right)-{P}_{out}\left({f}_{P}\right)+{P}_{in}\left({f}_{P}\right)$`

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.