SELECTED RF BLOCKS IN VHDL-AMS
131
Output impedance
out
Signal source
Figure 7-3. Block diagram of an RF-specific source model
The main characteristics of the modulated source models are as follows.
A sinusoidal source is modeled with amplitude modulation (AM)
2
1
sin(2
) sin(2
)
src
v
vo va
mdi
freqm t
phasem
freq t
phase
where va denotes the voltage amplitude that is computed from the power
amplitude parameter pa_dBm by
_
30
10
2
10
pa dBm
va
rout
Another architecture for the sinusoidal source is included with frequency
modulation (single frequency FM - SFFM)
2
sin 2
sin(2
)
src
v
vo va
freq t
phase mdi
freqm t
phasem
where va denotes the voltage amplitude that is computed from the power
amplitude parameter pa_dBm by
_
30
10
2
10
pa dBm
va
rout
Note: A factor of two is added in both cases since a power source has its
maximum power output when used in a matched system, where an
external resistor equal to the internal resistance is connected. In this case
the specified power amplitude can be measured.
The impedance of the output port is modeled as an ohmic resistance. A
typical value of a matched system is:
50
out
R
Summary :
A sinusoidal source is modeled with amplitude modulation (AM) 2 1 sin(2 ) sin(2 ) src v vo va mdi freqm t phasem freq t phase where va denotes the voltage amplitude that is computed from the power amplitude parameter pa_dBm by _ 30 10 2 10 pa dBm va rout Another architecture for the sinusoidal source is included with frequency modulation (single frequency FM - SFFM) 2 sin 2 sin(2 ) src v vo va freq t phase mdi freqm t phasem where va denotes the voltage amplitude that is computed from the power amplitude parameter pa_dBm by _ 30 10 2 10 pa dBm va rout Note: A factor of two is added in both cases since a power source has its maximum power output when used in a matched system, where an external resistor equal to the internal resistance is connected.
Tags :
amplitude,source,power,sin2,output,parameter,out,modulation,modeled,sinusoidal,computed,freq,system