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FM_DemodTuned (FM Demodulator, Tuned)

Symbol

Available in ADS

Parameters

Name

Description

Units

Default

Sensitivity

Demodulation sensitivity, in Hz/Volt

kHz

1

Fnom

Nominal input frequency

GHz

1

Rout

Output resistance

Ohm

50

Notes/Equations
  1. This is a tuned demodulator that selects the input harmonic closest to the specified Fnom frequency and generates a baseband output signal equal to the instantaneous frequency of the selected carrier frequency.
    If there is no analysis harmonic frequency close enough to the Fnom frequency, a warning is issued and the output is 0. Input impedance is infinite; output impedance is set by Rout, and is limited to a minimum value of 0.1 Ohm.
    The instantaneous frequency difference is equal to the time derivative of the instantaneous phase. This is approximated using a simple finite difference. As long as the phase does not change by greater than 180° in one time step, the frequency calculation is non-ambiguous. The open circuit output voltage can be described as:

    where

    k represents the value at the analysis harmonic frequency closest to the Fnom value
    0 represents the baseband component of the output voltage.
    All non-baseband output frequency components are 0.
  2. For transient and baseband envelope simulations, this model does not generate the expected results because the imaginary part of baseband signals is 0.
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