Why is a carrier recovery circuit necessary when using the AD630 for BPSK demodulation, and what are the common methods to achieve it?

Answer:

The AD630 does require a carrier recovery circuit for coherent demodulation.

There are two common methods for BPSK carrier recovery: one involves squaring the BPSK signal and dividing by two, while the other utilizes a 180° Costas loop. 

Please see the attached for reference.