Hi engineers of TI, I have a question about Op amp compensation and open loop transfer function：
There is a 0~10V input， 0~20mA output CCS as follows, the circuit is unstable at first,(especially when the load is capacitive). Transient response simulation results show that the output is oscillating.
So some compensate component(show as red line, include two resistor and one capacitance)be added to make the loop stable.
After compensate, Transient response simulation results show that the output is stabled.
Open-loop amplitude-frequency and phase-frequency simulation results show as below, the result show that gain margin of open loop is -38.12dB at first and15.79 after compensate.
So, What is the principle of the compensation circuit?
Because I just wanna figure out the effect of compensate part, I simplified the circuit (remove the transistor and simplify the differential amplifier to F), Simplified circuit show as follows.
What is the open loop transfer function(AF) of the Initial circuit and compensated circuit ？