9.2.2.10 Compensation
A type-II compensation circuit is adequate for the converter to have a phase margin between 60 and 90 degrees. The following equations show the procedure of designing a peak current mode control dc/dc converter.
The compensation design takes the following steps:
- Set up the anticipated cross-over frequency. In this example, the anticipated cross-over frequency (fc) is 65 kHz. The power stage gain (gmPS ) is 10 A/V and the GM amplifier gain (gM ) is 130 µA/V.
Equation 26.
- Place compensation zero at low frequency to boost the phase margin at the crossover frequency. From the procedures above, the compensation network includes a 20-kΩ resistor (R12) and a 4700-pF capacitor (C1).
- An additional pole can be added to attenuate high frequency noise.
From the procedures above, the compensation network includes a 20-kΩ resistor (R12) and a 4700-pF capacitor (C14).