I am using two PWM amplifiers for amplifying two PWM signals which are in 90degree out of phase. Both the amplifiers are run from the same dc power source and common ground. I am providing the PWM signals from function generator.

Now the problem is- in the output end the rising and falling of one signal is distorting the shape of another signal and vice versa. Can anyone tell me the probable reasons and how I can solve this problem.

thanks a lot in advance

 

Without a schematic, difficult to be precise. No voltages mentioned, no current mentioned, etc.
As a wild guess, you might put two diodes on the output of the power supply, one to feed each amplifier, and add a capacitor after each diode. This will keep the amplifiers somewhat isolated from each other.