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Digital or Analog Modulator and Demodulator?

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zigzagfish

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Hi, all, I am plan to design a Modulator and Demodulator chip with a CMOS process for the application of IEEE 802.15.4(Zigbee), my question is, 1. which modulation should I choose, GFSK, QPSK or sth else? 2. which kind of MoDem should I choose, Digital or Analog? Thank you!
 

DonJ

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Anything is possible, but digital and 'MSK' demodulator is a good combo.
Good luck.
 

jasnoch

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Hi,
The IEEE 802.15.4 Zigbee standard specifies to use BPSK or O-QPSK depending on band and data rate. Check out the IEEE 802.15.4 site to get full details. As for demodulation the simpliest and less power hungary way to go would be analog. A nice introduction to Zigbee standards can be found at. http://rfdesign.com/mag/radio_designing_zigbeeready_ieee/

Have fun.
 

zigzagfish

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oh, thank you all

I am not sure how to use analog ways to relize the MoDem. As you metioned, the analog way is more simple and less power consuming, but after refering to the commercial chips such as MC13191 and CC2420, they took the digital processing which confused me a lot.

You know, I am not so familiar with the fields of communicaiton.

:(
 

DonJ

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All commercial chips employ some kind of digital MODEM because it is most efficient. I am not sure what you really mean by analog modem in this case.:?:
 

zigzagfish

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In digital field, you can use A/D and D/A and process the signals with DSP or so.

My task is to design the chip with the help of CMOSs, but I do not know how to realize the similar functions using the cells of DFF, MUX etc.(May be it may not be considered as analog domain, but it is different to digital processor)

Would it be ok, thank you
 

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