I need to get some data from a SPI interface 16bit ADC and transfer
them through a 2 wire serial communication to a large signal processing
MCU/FPGA. If the data rate is not so high (say 2ksps, 16bit data -->32k bps),
I could use a small MCU like PIC/MSP430/AVR to do it. I could also use a
not-so-big MCU like an ARM7 to process the data.

If the data rate is high (say 20ksps from 16bit SAR ADC,
the data rate will be 320k bps). Perhaps a small MCU will not be able to
do the job.

I am not so familiar with CPLDs. Now I have some questions on the
possibility of using a small CPLD for this specific application.

How small this CPLD can be? Any recommendations?

I understand that the high data rate will also require a big MCU or
DSP or FPGA to process the data if I want to do some digital filtering.
But that is the next question...
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