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QPSK_ModTuned (QPSK Modulator, Tuned)

Symbol

Available in ADS

Parameters

Name

Description

Units

Default

Fnom

Nominal input frequency

GHz

1

Rout

Output resistance

Ohm

50

State1

Complex modulation coordinates of State 1

None

exp(−j × 1 × pi/4)

State2

Complex modulation coordinates of State 2

None

exp(−j × 3 × pi/4)

State3

Complex modulation coordinates of State 3

None

exp(−j × 5 × pi/4)

State4

Complex modulation coordinates of State 4

None

exp(−j × 7 × pi/4)

Notes/Equations
  1. This tuned quadrature phase shift keying (QPSK) modulator is actually an arbitrary 4-state modulator. The input harmonic closest to the specified Fnom frequency is selected and modulated by one of four user-defined complex values. If there is no analysis harmonic frequency close enough to the Fnom frequency, a warning is issued and the output is 0.
    The complex values are determined by the baseband component of the state modulation input. An input less than 0.5V selects State 1; less than 1.5V selects State 2; less than 2.5V selects State 3; and, any input greater than 2.5V selects State 4. The two input impedances are infinite. The output impedance is set by Rout and is limited to a minimum value of 0.1 Ohm. The open circuit output voltage is defined by:

    where
    k represents the value at the analysis harmonic frequency closest to the Fnom value
    0 represents the baseband component of the modulation state input voltage.
  2. The RF carrier is injected at pin 1; the input bit stream is injected at pin 3. The resulting QPSK signal is present at pin 2. The RF carrier should be a frequency-domain source; the modulating signal should be a time-domain source.
  3. This model will not function as a complex modulator in transient and baseband envelope simulations if the specified state values are complex.
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