I want to decode (in an fpga) the pdm signal that the admp522 returns in order to build a microphone array with one convergence point, but I was not able to find any information beyond that it is the output of a fourth-order sigma delta modulator. Could you either point me to more detailed information or give me suggestions for what the demodulation should look like? I am guessing it is not as simple as just low-pass filtering the signal. What are the integration times? Is some type of high order digital sinc filter what is required?