dressler6
Newbie level 6
I post it because of the frequency stability evaluation method in spectre(or hspice).
The example in the figure below is an example of the method I already know.
In the Fig.1 , it is simulated by putting 'stb' in the main loop (BLUE) on the output of -A2.
Also, for the stability of the local loop (RED), 'stb' is put in front of the input of 'A' to simulate.
The two simulations must be done separately.
Now the question I'm curious about.
This is the case when there is a local loop including output as shown in the Fig.2.
In the Fig.3,
if I put 'stb', it seems that the 'RED & BLUE' loop is the main loop to judge the stability.
If I put 'stb' as shown in the Fig.4,
it seems that stability can be judged with the loop of 'GREEN' as the main loop.
In order to judge the stability of this system, should it be judged by the 'stb' simulation performed twice for each of the 'RED & BLUE' and 'GREEN' loops?
The reason for asking this question is as follows.
In this system, shouldn't it be judged by only one simulation to make each main loop SUPERPOSITION?
When there is a change in the output signal, the feedback is applied to the two main paths at the same time, so shouldn't it be judged as a simulation that can SUPERPOSITION the two main paths?
If you know how to simulate superposition, please tell me.
The example in the figure below is an example of the method I already know.
In the Fig.1 , it is simulated by putting 'stb' in the main loop (BLUE) on the output of -A2.
Also, for the stability of the local loop (RED), 'stb' is put in front of the input of 'A' to simulate.
The two simulations must be done separately.
Now the question I'm curious about.
This is the case when there is a local loop including output as shown in the Fig.2.
In the Fig.3,
if I put 'stb', it seems that the 'RED & BLUE' loop is the main loop to judge the stability.
If I put 'stb' as shown in the Fig.4,
it seems that stability can be judged with the loop of 'GREEN' as the main loop.
In order to judge the stability of this system, should it be judged by the 'stb' simulation performed twice for each of the 'RED & BLUE' and 'GREEN' loops?
The reason for asking this question is as follows.
In this system, shouldn't it be judged by only one simulation to make each main loop SUPERPOSITION?
When there is a change in the output signal, the feedback is applied to the two main paths at the same time, so shouldn't it be judged as a simulation that can SUPERPOSITION the two main paths?
If you know how to simulate superposition, please tell me.