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IQ_Mod_Data (IQ Modulator Behavioral Model)

Symbol

Available in ADS

Parameters

Name

Description

Units

Default

Dataset

Name of dataset generated by IQ_Mod_Setup

None

dataset.ds

Freq

Carrier Frequency

GHz

1.0

Notes/Equations
  1. IQ_Mod_Data is a data-based system model of a circuit-level I/Q modulator. The circuit-level modulator is characterized by a dataset generated by the system component IQ_Mod_Setup.The use of this component is highlighted in the example project IQ_Mod_prj.
  2. The modulation behaviors are extracted for a single carrier frequency. Only the modulation distortions are characterized, so it is possible to set the frequency parameter in IQ_Mod_Data to differ from the value set in IQ_Mod_Setup. The modulation will occur at the frequency set in IQ_Mod_Data. The extracted distortions to the baseband signal as it passes through IQ_Mod_Data will be applied at this frequency. IQ_Mod_Data does not model any dispersion in these distortions across the baseband bandwidth.
  3. IQ_Mod_Data is designed for Circuit Envelope system verification where various filters typically eliminate unwanted frequency components. Therefore, IQ_Demod_Data makes no attempt to model harmonic components. The signal generated on RF output port is only a baseband signal modulated onto the carrier frequency. IQ_Mod_Data does not generate any frequency components at DC or at any harmonic of the carrier frequency.
  4. In order for IQ_Mod_Data to produce an accurate model of the circuit-level demodulator characterized via IQ_Mod_Setup, the Order parameter for IQ_Mod_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 an Order in the range of 10-15 is recommended for highly non-linear circuits. Providing this criterion is met, the Order parameter for the simulation controller can be very low when using IQ_Mod_Data in a Circuit Envelope simulation. Typically, an Order of approximately 3 should suffice for accurate demodulation modeling. Note, however, that accurate modeling of other components of the complete system may necessitate a larger value for this parameter.
  5. For a circuit-level modulator, the impedances presented by the input and output pins will generally be a complicated function of all state variables within the modulator. For the IQ_Mod_Data, a certain simplification is necessary as no information about the environment in which the modulator will later reside is known at the time of extraction. Specifically, IQ_Mod_Data presents a constant inward-looking impedance at the input and output pins. The input impedances at the baseband input pins are extracted at DC, while the impedance at the RF output pin is extracted at the RF carrier frequency specified in IQ_Mod_Setup.
  6. The extrapolation properties of IQ_Mod_Data above Pin-Stop are very poor. When using IQ_Mod_Data, please ensure that the input baseband signal does not exceed the Pin_Stop value set in IQ_Mod_Setup when the model was extracted. Note that the Pin_Stop value is in reference to the complex baseband signal, which is typically a factor of sqrt(2), or 3 dB, larger than the power of the signal at either individual input pin. Extrapolation to signal levels below the Pin_Start value set in IQ_Mod_Setup will generally be good as long as the Pin_Start value lies within the linear operating range of the modulator.
  7. IQ_Mod_Data does not model noise.
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