AnsweredAssumed Answered

AD9957 no output under Qduc mode

Question asked by loynis on Dec 24, 2014
Latest reply on Jan 5, 2015 by KennyG

In my recent project, I tried to config the AD9957 to work under QDUC mode. But I met a problem : the Ad9957 has no output.

I set the CFR1 CFR2 and CFR3 as follows:

CFR1= 8’h00 + 32’b 0000_0000_0000_0000_0000_0000_0000_0010;

CFR2= 8’h01 + 32’b 0000_0000_0000_0000_0010_1000_0010_0000;

CFR3= 8’h02 + 32’b 0001_1111_0011_1111_1100_0000_0000_0000;

Profile0 [63:32] = 32’h B400_0000;  (R = 45) Profile 0 addr is 8’h 0E;

Then config the profile 0[31:0] to set the FTW as a carrier frequency, and deliver the I/Q data into the chip(logic control by the pd_clk). After the step above, a PDCLK signal can be detect on the pin, and the frequency is just as what I set. The Tx_enable signal is also provide correctly. But the Ad9957 output kept 0. Then I tried to set the chip into Single Tone mode, and set the same FTW as above. The Ad9957 provided the correct output. I think this means the chip itself is ok.

I use an external PLL loop as an REF_CLK input, which the frequency is 368.64Mhz. My data rate is 2.048Mbps, so I set the R = 45; and active the PD_CLK control bit. The PD_clk can be detect on the pin which the freq is 2.048Mhz.

I would like to know what’s the problem? Thanks a lot.  

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