Perform frequency domain noise analysis
How to perform frequency domain noise analysis. A frequency domain noise analysis is performed in CW mode simulation. It corresponds to the calculation of the disturbance by a small signal noise of the HB CW. When the system is purely linear, it corresponds exactly to a noise analysis of AC type simulation on commercial circuit simulator. In this mode the noise is processed distinctly from the signal, which allows a very fast and accurate noise calculation.
To begin this task, you will need:
- A licence of VISION System Architect. See Installation and licence setup.
- To have opened a schematic. See Create or select a schematic
- An extracted LNA-B-HF or LNA-B-SP model in Device model including a Noise factor file . See Extract B-HF model for LNA device or Extract B-SP model for LNA.
The basic steps to perform a frequency domain noise analysis are:
-
Drag and drop the SIMCTRLR simulation controller block from the
palette window in Simulation controls section to the
schematic window.
Figure: Simulation controller 
-
Double-click on the SIMCTRLR block to open the Parameters window.
By default, the Simulation name is "sim0" and it is editable. Here we
change the simulation name for "sim3_LNA_B_HF_noise_freq_domain". In the
Simulation mode tab, choose the Simulation mode by selecting
CW simulation. Choose the Analyse type by selecting Sweep
analysis - nested sweep. In the Noise tab, choose the
Frequency domain noise analysis. In the Solver tab, choose the
Solver Type by selecting Algebraic solver I.
Figure: Simcontroller parameters 
-
Now we will set up the schematic to simulate a LNA-B-HF model or a LNA-B-SP
model. Drag and drop the LNA block from the palette window in
Non linear section to the schematic window. Double-click on
the LNA block to open the Parameters window and fill in the
Model parameter file field with the absolute or relative path of your
extracted model in device modeler with the extension ".head". Select the
parameter Add noise for this block to be taken into account in noise
analysis.
Figure: LNA block 
-
Drag and drop the CW-VS block from the palette window in
Source section to the schematic window. Double-click on the
CW-VS block to open the Parameters window and set the
amplitude of the CW signal provided by the source. Here we want to simulate in
small signal operation so we set -30 dBm. Also, select the parameter Add
noise for this block to be taken into account in noise
analysis.
Connect the CW-VS block output [+] with the input [in] of
the LNA block.
Figure: CW-VS source block 
-
Drag and drop the VAR2 block from the palette window in
Simulation controls section to the schematic window. We will
set up a frequency sweep. Double-click on the VAR2 block to open the
Parameters window. Then click on + to add a new variable.
Insert the parameters as in the following figure and click on OK to
create the variable then ok to confirm its creation in the VAR2
block.
-
Drag and drop the DC-VS block from the palette window in
Source section to the schematic window. We will use this block
to indicate the carrier frequency of the CW signal to the LNA block.
Double-click on the DC-VS block to open the Parameters window,
change the signal type to "real signal" and write "freq" in the DC
value parameter. Connect the DC-VS block output +
with the input fc of the LNA block.
Figure: Set the carrier frequency 
-
Drag and drop the RES block from the palette window in Linear
lumped section to the schematic window. We will use this block to
present a 50 Ohms load at the output of the LNA block. Double-click on
the RES block to open the Parameters window and set the resistance
to 50 Ohms. Connect the LNA block output [out] with the input
[+] of the RES block.
Figure: Present a load at the output of the HPA model 
-
We will place a probe to measure the noise factor NF. For the CW simulation, we
need to use the CW-NF block. Drag and drop the CW-NF block from
the palette window in Probe section to the schematic
window:
- Connect the CW-NF block input [in] with the LNA block input [in].
- Connect the CW-NF block output [out] with the LNA block output [out].
Figure: Noise figure probe 
-
The model can now be simulated. In the menu bar of the workspace window, click
on Simulate>Run simulation or on the shortcut
. The output console is displayed:
The console window contains the simulation time, the simulation mode, the repertory of the results, and also any warnings and errors encountered during the simulation. -
When closing the console window, simulation results appear in the application
tree in the folder named after the simulation "sim2_LNA_B_HF_noise_freq_domain".
In Workspace window, the Log shows console information. Click on
Output graphs tab to access the measurements provided by the
probe.
Figure: Output graph 