Post Go back to editing

Questions about AD9957 configuration for QPSK generation

Hello, I am an RF and MW engineer trying to figure out how to configure AD9957 to obtain a 1 MHz bandwidth QPSK signal at fc = 70 MHz. My conclusions up to now are that I should use the following values:

Fsysclk = 176 MHz

R = 44

FTW = 1,708,225,629 (not exactly 70 MHz of output frequency, but near enough)

Is that correct?

I also have some doubts on how to generate a QPSK. I mean in that kind of modulation I transmit 2 bits per symbol, but I should provide 18 bits per path (I or Q) to AD9957 parallel data input. How do I translate my 2 bits to all those bits I should put at data input?

Probably all those questions are quite simple to someone who is used to work with baseband, but it is a bit out of my scope, so I would appreciate any clarification. It also would help any advice or reminder of important facts that I should keep in mind to generate my signals.

Thanks for your support!

Parents
  • As a follow up, the AD9853 would have come very close to fitting your application. It was able to take in QPSK symbols directly as bit pairs (00, 01, 10, or 11), apply the necessary pulse shaping, and perform the requisite sample rate conversion!

    Unfortunately, the AD9853 is no longer in production. Besides, it was just a little too slow with a 65MHz max. carrier frequency and 165MHz max. system clock.

Reply
  • As a follow up, the AD9853 would have come very close to fitting your application. It was able to take in QPSK symbols directly as bit pairs (00, 01, 10, or 11), apply the necessary pulse shaping, and perform the requisite sample rate conversion!

    Unfortunately, the AD9853 is no longer in production. Besides, it was just a little too slow with a 65MHz max. carrier frequency and 165MHz max. system clock.

Children
No Data