Go to www.awrcorp.com
Back to search page Click to download printable version of this guide.

Tone(s) Source: TONE

Symbol

Summary

TONE generates one or more sinusoidal tones either in the complex envelope or as a real signal. Tone power is specified.

TONE supports phase noise, thermal noise, and impedance mismatch modeling. See Chapter 2 in the VSS Modeling Guide for details.

Parameters

Name Data Type Description Unit Type Default
ID N Element ID Text A1
FRQ R Tone frequencies Frequency 1 GHz
*FRQ_TDEP R Optional FRQ temperature dependence Frequency  
PWR R Tone powers Power in dB 10 dBm
*PWR_TDEP R Optional PWR temperature dependence    
PHS R Phase offsets Angle 0
*PHS_TDEP R Optional PHS temperature dependence Angle  
CTRFRQ R Center frequency Frequency  
SMPFRQ R Sampling frequency Frequency  
ZS C Source impedance Resistance _Z0
*ZS_TDEP C Optional ZS temperature dependence Resistance  
*ZSFREQS R Optional frequencies for frequency-dependent ZS Frequency  
*T_REF R Reference temperature for temperature dependent settings Temperature 16.85
*T_PHY R Physical temperature of device Temperature _TAMB
TN R Output noise temperature Temperature _TAMB
TN_TDEP R Optional TN temperature dependence Temperature  
NOISE E Thermal noise modeling N/A Auto
*TNRSEED I Thermal noise random number generator seeds Scalar  
PNMASK R Frequency characteristics for phase noise (freq-dBc/Hz pairs or data file) Scalar/String  
PNOISE E Phase noise modeling N/A No phase noise
*PNNFLT I Phase noise filter order Scalar 10000
*PNRSEED I Phase noise random number generator seeds Scalar  
*RFBSRC E RF Budget Analysis source frequency type N/A Auto
*SMPSYM R Samples per symbol Scalar _SMPSYM
*BLKSZ I Samples per pass Scalar _BLKSZ*_SMPSYM
*IVARTYP   Treatment of numeric independent variables in PNMASK data files (VAR)   Allow any value for numeric

* indicates a secondary parameter

Parameter Details

FRQ. The tone frequencies. Enter a vector of frequencies for multiple tones, for example {1.5,2.5,3.5} GHz for three tones at 1.5, 2.5, and 3.5 GHz, or use the "stepped" command, as in stepped(1.5e9,3.5e9,1e9). Please note that when using the stepped command or a variable, the frequency units revert to the basic frequency unit (Hz), even if the default unit of the project (specified under Options > Project Options > Global Units) is something else.

FRQ_TDEP. Specifies the rate of change of the FRQ parameter over temperature. See Section 2.6 in the VSS Modeling Guide for details on how to use temperature dependent parameters.

PWR. The power for each tone. If there are fewer values for the power than there are tone frequencies in FRQ, the last power value is repeated. If set to a single value, all tones have that power. If the signal is complex, PWR is single-sided power if the center frequency is non-zero and double-sided power if the center frequency is zero.

PWR_TDEP. Specifies the rate of change of the PWR parameter over temperature. See Section 2.6 in the VSS Modeling Guide for details on how to use temperature dependent parameters.

PHS. The phase offsets for each tone. If there are fewer values for the phases than there are tone frequencies in FRQ, the last phase value is repeated.

PHS_TDEP. Specifies the rate of change of the PHS parameter over temperature. See Section 2.6 in the VSS Modeling Guide for details on how to use temperature dependent parameters.

CTRFRQ. The center frequency for the complex envelope signal. If this is left empty, the center frequency is set to the average of all the tone frequencies.

SMPFRQ. The sampling frequency for the signal. If left empty this will be determined automatically, as follows. If there is nothing else in the signal path downstream to help determine a sampling frequency, then the sampling frequency is set to _SMPFRQ = _DRATE * _SMPSYM from the Options > Default System Options menu of the project. The sampling frequency can also be back-propagated to the TONE block when it is specified somewhere else in the chain. For example, this happens when a signal with specified sampling frequency goes through a mixer (or adder, combiner, etc.) for which TONE is the LO. Then the sampling frequency of TONE is set to the value back-propagated through the two-input block.

ZS, ZSFREQS. ZS is the source impedance of the generator. Frequency-dependent source impedances may be specified by entering a vector of source impedances in ZS and a vector of the corresponding frequencies in ZSFREQS. Impedances between the frequency points are linearly interpolated using the magnitude and phase of the impedances at the frequency points.

ZS_TDEP. Specifies the rate of change of the ZS parameter over temperature. See Section 2.6 in the VSS Modeling Guide for details on how to use temperature dependent parameters.

T_REF. The reference temperature for the temperature dependent settings.

T_PHY. The physical temperature of the device. This determines the amount of noise generated by the block when noise modeling is enabled.

TN. The noise temperature of noise generated by the block if noise is enabled for the simulation type by NOISE. The noise generated is white noise.

TN_TDEP. Specifies the rate of change of the TN parameter over temperature. See Section 2.6 in the VSS Modeling Guide for details on how to use temperature dependent parameters.

NOISE. Determines how thermal noise is to be modeled:

  • RF Budget only: Noise is modeled for RF Budget Analysis simulations, but not Time Domain simulations.

  • RF Budget + Time Domain: Noise is modeled for both RF Budget Analysis and Time Domain simulations.

  • Noiseless: The block is assumed to be noiseless in all simulations.

  • Auto: The setting is determined from the RF Noise Modeling setting on the RF Optionstab of the System Simulator Options dialog box.

TNRSEED. The seed for the Time Domain simulation's thermal noise pseudo-random number generator. See RND_D for details.

If this is left empty, a seed is generated based on a hash of the block name and the ID parameter (if the block is within a subcircuit, the ID parameters of the parents are also used). In general, this results in different instances of the block generating different sequences, although it is not guaranteed.

If this is set to -1, the seed varies from sweep to sweep in a single simulation run. An initial seed value similar to that generated from the block name and ID parameter is used, with a different offset added to it each new sweep. The seed sequence is deterministic between simulation runs.

PNMASK. This may either be a vector of frequency offset-dBc/Hz pairs or the name of a data file object under the Data File object of the Project Browser. This data file should be a Text Data File that contains frequency offset-dBc/Hz data.

If a vector is specified, it must contain an even number of values, with each pair of values representing a frequency offset from the carrier in hertz and the phase noise level in dBc/Hz. The following example represents a phase noise mask specifying a phase noise level of -30 dBc/Hz at 1000 Hz and -75 dBc/Hz at 10000 Hz:

PNMASK = {1000, -30, 10000, -75}

If a data file is used, it should contain two columns, with the first column representing frequency offsets and the second column representing the phase noise level in dBc/Hz:

    (,Hz)    (,dBc)
    1000     -30
    10000    -75

Independent variables are also supported in the data file. Independent variables let you specify several different data sets, each with different values for the independent variables. The independent variables are added to the end of the block's parameter list, letting you select a specific data set. The parameters can be swept, so you can sweep the simulation using different data sets.

Independent variables are specified before the header row of each data set. They have the form VAR name = value, where 'name' is the independent variable's name, and 'value' is the value associated with the independent variable. The name must only contain the characters 'A' through 'Z', 'a' through 'z', '0' through '9', and '_'. The name must also differ from the other parameters of the block. The value may be numeric or text. If text, you can include spaces by enclosing the text within quotation marks as follows.

    VAR Config = A

    VAR Config = "High Power"

    VAR Temp = 290

There may be more than one independent variable. Each data set should have an entry for each independent variable.

The parameters associated with independent variables whose values are text always appear as a drop-down list containing the available values. The parameters associated with independent variables whose values are all numeric can be configured to either display a drop-down list containing the available values or can be configured to accept a numeric value. The configuration is determined by the IVARTYP parameter. When IVARTYP is set to "Allow any value for numeric" the data set whose independent variable's value is closest to the entered parameter value is selected.

NOTE: The ability to generate time domain phase noise matching the phase noise mask is limited by the sampling frequency and the total phase noise to be generated. As the average phase noise generated by the FIR filter bins approaches or exceeds the inverse of the sampling frequency, the phase noise samples wrap around ±π and the phase noise samples effectively alias. Section 3.4.2 in the VSS Modeling Guide details the equations involved.

PNOISE. Determines how phase noise is to be modeled.

PNNFLT. The filter order of the FIR filter used to shape the phase noise spectrum. If an odd value is specified, one will be added to make the filter order even.

PNRSEED. Seeds for the random number generator used to generate phase noise samples. Up to four values may be entered. If this is left empty, the seed will be generated based on the block name and ID parameter.

RFBSRC. Determines how the RF Budget Analysis frequencies for this source are determined. The frequencies are computed by adding the frequency offsets specified in the RF Frequencies tab of the System Simulator Options dialog box to a base frequency, which is determined by the selected RFBSRC option:

  • Auto: If the signal is a real signal, and only one frequency offset was specified, the behavior will be the same as "Signal Frequency", otherwise the behavior will be the same as "Center Frequency (v7.5)". This behavior lets you easily configure an RF Budget Analysis simulation for mixers using real signals.

  • Center Frequency (v7.5): The frequencies are computed by adding the frequency offsets to the center frequency. This is the same behavior as Visual System SimulatorTM (VSS) v7.5 software.

  • Signal Frequency: The frequencies are computed by adding the frequency offsets to the average of the frequencies in FRQ. This is useful if the center frequency cannot be the same as FRQ, or if a real signal is being generated.

SMPSYM. The number of samples per symbol associated with the signal. Although not directly applicable to RF tones, samples per symbol is used by various blocks to define a data bandwidth, which is the sampling frequency divided by the samples per symbol.

BLKSZ. The number of samples generated each time the block is visited.

IVARTYP. Determines the behavior of the dynamic parameters representing the independent variables within the data file whose values are all numeric.

  • Allow any value for numeric, pin to nearest: The parameters allow any numeric value, and the data set whose independent variable is closest to the parameter value is used.

  • Select from list: The parameters display a list of available values for the independent variables.

Data Output

Node No. Type Purpose
1 Real, Complex Output Signal

Implementation Details

If the output signal is a complex signal, a complex envelope signal is generated of the form:

where ~s(t) is the complex envelope signal at center frequency CTRFRQ and A[i] is the voltage amplitude corresponding to PWR at FRQ.

If the output signal is a real signal, the generated signal has the form:

Noise Modeling

If thermal noise samples are generated, noise samples are added to the generated signal. The samples have an rms value of:

where k is Boltzmann's constant, T is the noise temperature parameter in Kelvin, and B is the bandwidth. For real and complex envelope signals with center frequency of 0 B is 1/2 the sampling frequency. For complex envelope signals with non-zero center frequency B is the sampling frequency. Vn,out represents the rms voltage of a noise source with temperature T if the output is connected to a resistance of Re{ZS}.

If impedance mismatch modeling is enabled, Vn,out is adjusted to reflect the voltage that would be seen by the load:

If phase noise samples are generated, noise samples with a frequency spectrum matching the phase noise mask are added to the phase of the signal. The phase noise samples are generated by passing white noise samples through an FIR filter representing the phase noise mask. See the Phase Noise Source block PHASENS for details.

The PHS_NOISE measurement can be used to view the phase noise in dBc/Hz in Time Domain simulations. The C_PHS_NOISE measurement can be used to view the phase noise in RF Budget Analysis measurements.

Impedance Mismatch Modeling

The output signal is corrected by:

If impedance mismatch modeling is enabled, ZL,f is the load impedance seen by the block for frequency f. If it is not enabled, then ZL,f is the default characteristic impedance _Z0, defined in the Options dialog box of the system diagram. Impedance mismatch modeling is enabled via the Options dialog box of the system diagram.

RF Inspector/RF Budget Analysis

The block fully supports both RF Inspector and RF Budget Analysis simulations. See the Chapter 2 in the VSS Modeling Guide for details.

Please send email to awr.support@ni.com if you would like to provide feedback on this article. Please make sure to include the article link in the email.

Legal and Trademark Notice