when simulating the system, the warning:division by zero in amplifier/product arises, how to deal with it? the amplifier is selected from RF Blockset/Mathematical/amplifier.

the system is a BPSK transmitter using class E power amplifier. I simplify the system by assuming input signal is a constant envelope signal. so power amplifier could be considered as linear for phase signal. as a result I just use a amplifier block to model it. is it right? could you give me some advices to model class e power amplifier in simulink?

I use the transport delay blocks for I/Q paths, how to set up the buffer size for them?