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VCA_Data (Voltage Controlled Amplifier)

Symbol

Available in ADS

Parameters



Name Description Units Default
Dataset Name of dataset generated by VCA_Setup model None dataset.ds
InstrumentID ID of VCA_Setup extractor used to generate dataset None X1
iVarN Name of Nth multi-dimensional variables N={1,...,N}; use if present in P2D file None None
iValN Value of Nth multi-dimensional variables N={1,...,N}; use real or integer values only None None
† If multi-dimensional variables are present in the Dataset, then these variables are required to be listed in iVarN as indicated in note 11 and corresponding values assigned to them using the iVaN parameter.Multidimensional VCA datasets are generated using parametric sweeps over the VCA_Setup component.

Notes/Equations
  1. VCA_Data is a data-based system model of a circuit-level VCA. The circuit level VCA is characterized by a dataset generated by the system component VCA_Setup. The use of this component is highlighted in the example project VCA_prj.
  2. VCA_Data is the most advanced data-based system amplifier. If no special circumstances make AmplifierS2D, AmplifierP2D, AmpH1H2 or AmpLoadPull superior to VCA_Data, the latter model should be used for data-based system modeling of amplifiers. Since the VCA_Data does not have provisions for explicit control of frequency, order of harmonics or bias voltage at the instance level, it is advised that behavioral simulation and extraction simulation environments be closely matched for reliable modeling.
  3. VCA_Setup and VCA_Data work equally well for amplifiers with or without a control voltage. For amplifiers without a control voltage, the control pin should be grounded.
  4. VCA_Data is designed for Harmonic Balance or Circuit Envelope system verification (ACPR, BER, etc.) where various filters typically eliminate unwanted frequency components. Therefore, VCA_Data makes no attempt to model harmonic components. This means that for a 1-tone Harmonic Balance simulation at frequency f, only the frequency component at f (fundamental) is retained. All others will be invalid or zero as they are assumed to be filtered later.
    For a 2-tone Harmonic Balance simulation at frequencies f1 and f2 (practically very close), only the frequency components at f1 and f2 (fundamentals) and those at 2 x f1-f2 and 2 x f2-f1 (intermodulation) are retained. These frequency components are very close and filtering cannot be guaranteed. All other frequency components are invalid or zero, it is assumed that they will be filtered later. Similarly, for a Circuit Envelope simulation, narrowband modulated components around the carrier(s) are retained. All others are invalid or zero, it is assumed they will be filtered later.
    VCA_Data will also run in Transient but this is not a recommended simulation controller. Since VCA_Setup is based on Harmonic Balance analysis, the dataset created by VCA_Setup contains steady-state information only. Transient analysis can only predict the correct steady-state response. This likely to result in an incorrect transient response.
  5. In order for VCA_Data to produce an accurate model of the circuit-level VCA characterized via VCA_Setup, the Order parameter for VCA_Setup must be large enough to prevent aliasing of higher-order frequency components. For mildly non-linear circuits, an Order of approximately 5 should suffice while a range of 10-15 is recommended for highly non-linear circuits. Provided this criterion is met, the Order parameter for the simulation controller can be very low when using VCA_Data in a Harmonic Balance or Circuit Envelope simulation. Typically, an Order of approximately 3 should suffice for accurate VCA modeling. However, accurate modeling of the other components in the complete system may necessitate the need for a larger value for this parameter.
  6. For a circuit-level VCA, the impedances presented by the input, output and control pins are usually highly complicated functions of all state variables within the circuit of which the VCA is part. For a data-based VCA, a simplification is necessary because no information about the environment in which the VCA will be placed is known at the time of extraction. Specifically, VCA_Data presents an input power and control voltage dependent impedance at the input, output and control pins, with the input and control impedances assuming an open-circuit output pin. The input and output impedances are voltage-to-current ratios at RF while the control impedance is a voltage-to-current ratio at DC.
  7. Assuming proper sampling, the interpolation properties of VCA_Data are generally good, but occasionally break down near the limits of the ranges to which input power and control voltage were constrained when generating the dataset using VCA_Setup. To safe-guard against such a breakdown, the upper and lower limits of these ranges can be extended about 6 dB in input power and 1 V in control voltage.
  8. The extrapolation properties of VCA_Data are very poor. When using VCA_Data, please ensure that input power and control voltage are within the ranges to which input power and control voltage were constrained when generating the dataset using VCA_Setup.
  9. VCA_Data does not model noise.
  10. VCA_Setup and VCA_Data can be used for simulating an amplifier with an arbitrary swept control parameter, for example, a temperature. Simply convert a 2-pin amplifier dependent on a given parameter, in this case Par, to a 3-pin amplifier with the third pin connected to a grounded DC voltage source whose strength equals Par. By sweeping the control voltage of VCA_Setup in the desired parameter range for Par and subsequently connecting the control pin of VCA_Data to a grounded DC voltage source, Par values in the appropriate range can be selected by setting the strength of this voltage source properly.
  11. The response of VCA_Data can be user-selected from a body of a multi-dimensional VCA dataset by specifying the names and values of such variables in the iVarN and iValN parameters prior to behavioral simulation. Details of multi-dimensional VCA dataset generation are discussed in Notes/Equations in the VCA_Setup component documentation. If a given multi-dimensional VCA dataset contains "V" variables in the form of external sweeps above the Vcontrol sweep, then the names of these variables need to be assigned to an iV arN parameter of the VCA_Data instance. Although the ordering of these names can be arbitrary relative to the order in the P2D file, the existence and ordering of values in the i Val1 through iValV parameters should always correspond to those in iVar1 through iVarV . If a multi-dimensional variable contained in the VCA dataset is not specified in the iVarN of a VCA_Data instance reading that file, then the simulation will be terminated due to insufficient data for multi-dimensional data indexing. Only real and integer values of multidimensional iVarN are supported.
  12. A number of new features have been added to enhance the performance of VCA_Data in the ADS2004A release. Please note that the ADS2004A version of VCA_Data is compatible only with datasets generated by the ADS2004A version of VCA_Setup. If a VCA dataset generated by an earlier version of the extractor model is applied to a new version of the data model, an error message is generated asking the user to re-perform the extraction process prior to behavioral modeling.
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