Infineon XMC Series - Open Loop Gain Bode Plot, Current Mode Stabilization

Introduction to Digital Power Conversion
XMC4000/1000 Family
Control Loops
Application Guide 87 V1.0, 2015-01
7.4.4 Open Loop Gain Bode Plot, Current Mode Stabilization
The voltage mode control open loop gain is a product of the following transfer functions:
H
ADC
(s) * H
II
(s) * H
DC
(s) * H
HF
(s) * H
SS
(s)
(Assume H
ADC
(s) = 1)
Bode-Plot
The vertical co-ordinate of the Bode-Plot diagram is logarithmic in dB (decibel) scale. The absolute
value of the total transfer function will be plotted according to:
|H
II
(s) * H
DC
(s) * H
HF
(s) * H
SS
(s)|
dB
This may also be expressed as:
|H
III
(s)|
dB
+ |H
DC
(s)|
dB
+ |H
HF
(s)|
dB
+ |H
SS
(s)|
dB
These additions give the Bode-plots in the following figure
Figure 71 Peak Current Mode Control Open Loop Gain – Frequency Compensation
Note: The H
II
(s) is a Type-II filter and can be realized by software in XMC devices (with software
Library support).