PA module

Here is an interview question:
Power amplifier modules used in handset generally consists of GaAs HBT amplifiers, CMOS controller and laminate boards. Break down the raw material cost and development cycle for each component. Use your best judgement and state the assumptions used in the estimate.

If somebody has experience with this area,please reply.Thanks.

the reason of use the BJT as the pa of the handset is that it can carrier more current density than other device when the same volume of the device is used!