Hi guys I'm currently working on my MOSFET project.
I've first constructed the small-signal model of this circuit and changed each value of the device so that I can see the tendency.
While doing so, I've faced some tendency that I cannot understand.
The circuit diagram and AC sweep results are attached.
When I increase Width(W) of M19, the current generated by IAC(I12) seems to be sucked up to the gate of M19 on high frequency.
The first result is when the Width of M19 is 1u. The current generated by the IAC(1A) is red line. It decreases on high frequency but not considerably.
The second result is when the Width of M19 is 100u. The red line starts to decrease dramatically and the green line, the current on gate of M19, increases at the same time.
It seems like as the Width of M19 increase, it starts to 'suck up' the current on lower frequency. And it also changes the pole location(The pole location of curve of current through load cap, C19 in schematic).
I may guess that this is because of some capacitance between gate of M18 and M19 but I have no idea how should I understand and explain this.
There are some high-frequency model of MOSFET on google, but there aren't any model for this kind.
Can you give me some advice to understand/explain it?
I've first constructed the small-signal model of this circuit and changed each value of the device so that I can see the tendency.
While doing so, I've faced some tendency that I cannot understand.
The circuit diagram and AC sweep results are attached.
When I increase Width(W) of M19, the current generated by IAC(I12) seems to be sucked up to the gate of M19 on high frequency.
The first result is when the Width of M19 is 1u. The current generated by the IAC(1A) is red line. It decreases on high frequency but not considerably.
The second result is when the Width of M19 is 100u. The red line starts to decrease dramatically and the green line, the current on gate of M19, increases at the same time.
It seems like as the Width of M19 increase, it starts to 'suck up' the current on lower frequency. And it also changes the pole location(The pole location of curve of current through load cap, C19 in schematic).
I may guess that this is because of some capacitance between gate of M18 and M19 but I have no idea how should I understand and explain this.
There are some high-frequency model of MOSFET on google, but there aren't any model for this kind.
Can you give me some advice to understand/explain it?
Attachments
-
34 KB Views: 14
-
15 KB Views: 14
-
17.3 KB Views: 7