
Feedback Loop Analysis and Stability
Therefore, on doubling the input,
V
O
2 × V
IN
=
D
2
which is what we are doing anyway, through feedforward. So, we can see that this simple
feedforward technique will work very well for a buck. However, for a boost or a
buck-boost, the duty-cycle-to-input proportionality is clearly not going to be the best
answer.
Using voltage feedforward to produce automatic line rejection is clearly applicable only to
voltage mode control. However, the original inspiration for this idea came from current mode
control. But in current mode control, the ramp to the PWM comparator is being generated
from the inductor current waveform. ...