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AD9268 output amplitude is small

Question asked by madge on Aug 27, 2017
Latest reply on Sep 5, 2017 by PMH

Hello All, 

    I use the FPGA to control and capture images with CHIPSCOPE,The amplitude is small and there is a lot of noise,Please look at these pictures.When I use DA to collect out and observe with a spectrum analyzer.My input is -5dbm  but the output is -33dbm.Can you help me analyze the problem?Here are the main register values.The first 16 bits are the address, and the last 8 bits are data.

 

spi_port =24'h000018;

 channel =24'h000503;
 power_mode =24'h000880;
transfer =24'h00ff01;
global_clk =24'h000901;
 clk_divide =24'h000b00;
test_mode =24'h000d04;
 bist_en =24'h000e01;
 adc_input =24'h000f00;
 offset =24'h001000;
 output_mode =24'h001401;

 dco_out =24'h001700;
 vref =24'h0018C0;

 

This is my circuit.I hope to get your reply as soon as possible.Thanks very much.

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