XDB Simulation Parameters

The Gain-Compression (Xdb) Simulation controller enables you to define these aspects of the simulation:

Freq

Following are descriptions of the fields to set up frequency for this component. In the following table, names used in netlists and ADS schematics appear under Parameter Name .

XDB Simulation Freq Options  
Setup Dialog Name Parameter Name Description
Fundamental Frequencies
Edit   Edit the Frequency and Order fields, then use the buttons to Add the frequency to the list displayed under Select.
  Frequency Freq[n] The frequency of the fundamental(s). Change by typing over the entry in the field. Select the units (None, Hz, kHz, MHz, GHz) from the drop-down list.
Order Order[n] The maximum order (harmonic number) of the fundamental(s) that will be considered. Change by typing over the entry in the field.
Select   Contains the list of fundamental frequencies. Use the Edit field to add fundamental frequencies to this window. Add -- Allows you to add an item. Cut -- Allows you to delete an item. Paste -- Allows you to take an item that has been cut and place it in a different order.
Maximum mixing order MaxOrder The maximum order of the intermodulation terms in the simulation. The combined order is the sum of the individual frequency orders that are added or subtracted to make up the frequency list. For example, assume there are two fundamentals and Order (see below) is 3. If Maximum order is 0 or 1, no mixing products are simulated. The frequency list consists of the fundamental and the first, second, and third harmonics of each source. If Maximum order is 2, the sum and difference frequencies are added to the list. If Maximum order is 3, the second harmonic of one source can mix with the fundamental of the others, and so on.
Levels-Enables you to set the level of detail in the simulation status report.
  Status level StatusLevel Prints information about the simulation in the Status/Summary part of the Message Window. A value of 0 causes no or minimal information to be reported, depending on the simulation engine. Higher values print more detail. The type of information printed may include the sum of the current errors at each circuit node, whether convergence is achieved, resource usage, and where the dataset is saved. The amount and type of information depends on the status level value and the type of simulation.

XdB

Following are the fields used to define XDB simulation. In the following table, names used in netlists and ADS schematics appear under Parameter Name .

XDB Simulation X  dB Options  
Setup Dialog Name Parameter Name Description
Gain compression GC_XdB Enter the gain compression, the default is 1 dB.
Port numbers
  Input GC_InputPort The number of the input port.
Output GC_OutputPort The number of the output port.
Port frequencies-Ports must be placed and defined. Set the port number of the input source to1, and the port number of the output Term (termination) component to 2, then set frequencies.
  Input GC_InputFreq The frequency of the input port.
Output GC_OutputFreq The frequency of the output port.
Power tolerances
  Input GC_InputPowerTol The variation in power, measured as a change in dB (delta dB), allowed at the input port.
Output GC_OutputPowerTol The variation in power, measured as a change in dB (delta dB), allowed at the input port.
Max. Input Power GC_MaxInputPower The maximum input power (in dBm) allowed before the simulator aborts. This setting is used to prevent the simulator from continuing to search if it is having difficulty finding a solution.

Defining Simulation Parameters

Defining the simulation parameters consists of four basic parts:

XDB Simulation Parameter Options  
Setup Dialog Name Parameter Name Description
Device operating point level DevOpPtLevel Enables you to save all the device operating-point information to the dataset. In ADS, if this simulation performs more than one XDB analysis (from multiple XDB controllers), the device operating point data for all XDB analyses will be saved, not just the last one. Default setting is None.
  None None No information is saved.
Brief Brief Saves device currents, power, and some linearized device parameters.
Detailed Detailed Saves the operating point values which include the device's currents, power, voltages, and linearized device parameters.
FFT
  Fundamental Oversample FundOversample Sets the FFT oversampling ratio. Higher levels increase the accuracy of the solution by reducing the FFT aliasing error and improving convergence. Memory and speed are affected less when the direct harmonic balance method is used than when the Krylov option is used.
More... Oversample[n] Displays a small dialog box. To increase simulation accuracy, enter in the field an integer representing a ratio by which the simulator will oversample each fundamental.
Initial Guess
  Use Initial Guess UseInFile Check this box to enter a file name for a solution to be used as initial guesses. This file is typically generated from a previous simulation by enabling Write Final Solution. If no initial guess file name is supplied, a default name (using DC solution) is generated internally, using the design name and appending the suffix .hbs. A suffix is neither required nor added to any user-supplied file name. For example, if you have saved the Harmonic Balance solution from a previous simulation, you can later do a nonlinear noise simulation and use this saved solution as the initial guess, removing the time required to recompute the nonlinear Harmonic Balance solution. Or you could quickly get to the initial Harmonic Balance solution, then sweep a parameter to see the changes. In this latter case, you will probably either want to disable the Write Final Solution option or use a different file name for the final solution to avoid overwriting the initial guess solution. (See Write Final Solution option below.) The Annotate value specified in the DC Solutions tab in the Options block is also used to control the amount of annotation generated when there are topology changes detected during the reading of the initial guess file. Since HB simulations also utilize the DC solution, to get optimum speed-up, both the DC solution and the HB solution should be saved and re-used as initial guesses. See DC Simulation. The initial guess file does not need to contain all the HB frequencies. For example, one could do a one-tone simulation with just a very nonlinear LO, save that solution away and then use it as an initial guess in a two tone simulation. The exact frequencies do not have to match between the present analysis and the initial guess solution. However, the fundamental indexes should match. For example, a solution saved from a two tone analysis with Freq[1] = 1GHz and Freq[2] = 1kHz would not be a good match for a simulation with Freq[1] = 1kHz and Freq[2] = 1 GHz. If the simulator cannot converge with the supplied initial guess, it then attempts to a global node-setting by connecting every node through a small resistor to an equivalent source. It then attempts to sweep this resistor value to a very large value and eventually tries to remove it.
File InFile Specify a filename to save results.
Regenerate Initial Guess for ParamSweep (Restart)    
Final Solution
  Write Final Solution UseOutFile Check this box to save your final HB solution to the output file. If a filename is not supplied, a file name is internally generate using the design name, followed by an .hbs suffix. If a file name is supplied, the suffix is neither appended nor required. If this box is checked, then the last HB solution is put out to the specified file. If this is the same file as that used for the Initial Guess, this file is updated with the latest solution. Transient simulations can also be programmed to generate a harmonic balance solution that can then be used as an initial guess for an HB simulation. Refer to Harmonic Balance Simulation.
File OutFile Specify a filename to save results.
Budget
  Perform Budget simulation OutputBudgetIV Enables Budget simulation, which reports current and voltage data at the pins of devices following a simulation. Current into the nth terminal of a device is identified as ...device_name.tn.i. Voltage at the nth terminal of a device is identified as ...device_name.tn.v.
Harmonic Balance Assisted Harmonic Balance HBAHB_Enable Set the HBAHB mode to Auto, On, or Off. Default is Auto and is recommended.

Solver

Refer to the topic "Selecting a Harmonic Balance Technique" in the chapter "Harmonic Balance Basics" in the Harmonic Balance Simulation documentation.

 

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