CAMALEAO
Full Member level 4
Hi everyone,
I have designed a simple 2 stage amplifier. For this amplifier, I did a small experiment. Using the traditional compensation with a simple resistance and using a MOSFET.
I got one value for the resistance which gave me a reasonable phase margin and all that. Then, when I implemented the compensation with the MOSFET, I put more or less the same resistance value.
However, I got a different phase margin which at first sight doesn't make sense. Then I drew a small equivalent circuit using only the parasitics capacitances of the MOSFET in the second stage and the mosfet used as a resistor and I saw that the problem could be related to this.
Has anyone experienced this? Do you guys normally use this kind of compensation with a MOSFET as a resistor? Can you share your thoughts on this?
Regards.
I have designed a simple 2 stage amplifier. For this amplifier, I did a small experiment. Using the traditional compensation with a simple resistance and using a MOSFET.
I got one value for the resistance which gave me a reasonable phase margin and all that. Then, when I implemented the compensation with the MOSFET, I put more or less the same resistance value.
However, I got a different phase margin which at first sight doesn't make sense. Then I drew a small equivalent circuit using only the parasitics capacitances of the MOSFET in the second stage and the mosfet used as a resistor and I saw that the problem could be related to this.
Has anyone experienced this? Do you guys normally use this kind of compensation with a MOSFET as a resistor? Can you share your thoughts on this?
Regards.