The bandwidth of the modulated signal is twice the bandwidth of the modulating signal in case of analog amplitude modulation..
But in the case of digital modulation (ASK), the bandwidth of the resulting signal is equal to the Baud rate. How the two cases are different from each other ?
ASK bandwidth is given by this formula
B=(1+d)*S
where
B is the bandwidth
S is the signal rate
d is between 0 and 1 (depend on modulation and filtering)