BCA filter

[lumanauw]

I try to simulate a simple half bridge LC filter, L=22uH, C=1uF, load=4ohm.

 

[lumanauw]

The response is like this

 

[lumanauw]

Now I add 2 diodes and 1 extra inductor, to make a BCA output stage.

 

[lumanauw]

Why is the response become like this? The peak is about +18.5dB.
What is wrong with my SIM? Changin the values of L or C don't help.

 

[kASD]

The Gate drive to both devices in BCA is always in phase and hence the devices conduct simuntaneously!! whereas your diagram shows simple complementary halfbridge, in which device conduction is based on appropriate polarity of signal with respect to channel polarity of device
Also the inductors used in BCA are atleast 220uH not 22uH.