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
- 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. - 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.
- This model will not function as a complex modulator in transient and baseband envelope simulations if the specified state values are complex.