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FMCOMMS1 AD9523 configuration problems

Question asked by Lionel on May 16, 2014
Latest reply on May 26, 2014 by Lionel

 

Hi,

 

 

We have some problem when we try to reconfigure AD9523  PLL of FMCOMMS1.

 

We use this card with non-os software with VC709 board.

 

We try to configure the AD9523 to work with a 10 MHz input clock.

 

We have modified the AD9548 and the FPGA code to provide 10MHz clock in REFB input. We want also be able to switch on RefA to provide an external 10MHz clock.

 

 

We do this configurations for the AD9523 :

(extract of AD9523_cfg.h)

 

------------------------------------------------------------------------------------------------

struct ad9523_channel_spec ad9523_channels[] =

{

{     /* ZD output */

0,  //channel_num

0,  //divider_output_invert_en

0,  //sync_ignore_en

0,  //low_power_mode_en

0,  //use_alt_clock_src

0,  //output_dis

LVDS_4mA, //driver_mode

0,  //divider_phase

16,  //channel_divider

"ZD_OUTPUT", //extended_name

},

 

….

…..

…..

 

 

…..

 

 

 

struct ad9523_platform_data ad9523_pdata_lpc =

{

122880000, //vcxo_freq

 

/* Single-Ended Input Configuration */

0,  //refa_diff_rcv_en

1,  //refb_diff_rcv_en

1,  //zd_in_diff_en

0,  //osc_in_diff_en

 

0,  //refa_cmos_neg_inp_en

0,  //refb_cmos_neg_inp_en

0,  //zd_in_cmos_neg_inp_en

1,  //osc_in_cmos_neg_inp_en

 

125, //refa_r_div

125, //refb_r_div

768,  //pll1_feedback_div => input is 10 Mhz

2000,   //pll1_charge_pump_current_nA

0,  //zero_delay_mode_internal_en

0,  //osc_in_feedback_en

3,  //pll1_loop_filter_rzero

 

SELECT_REFB, //ref_mode

 

420000, //pll2_charge_pump_current_nA

0,  //pll2_ndiv_a_cnt

3,  //pll2_ndiv_b_cnt

1,  //pll2_freq_doubler_en

1,  //pll2_r2_div

3,  //pll2_vco_diff_m1

3,  //pll2_vco_diff_m2

 

0,  //rpole2

2,  //rzero

2,  //cpole1

0,  //rzero_bypass_en

 

/* Output Channel Configuration */

ARRAY_SIZE(ad9523_channels), //num_channels

ad9523_channels, //channels

"ad9523-lpc" //name

};

 

 

 

 

We observe that the  PLL1 and PLL2 are locked but there is a frequency sweep on the output of TX RF (approximately 15KHZ of sweep).

 

The test was made with FMCOMMS1 Rev B.

 

 

 

Thanks,

 

Bests regards,

 

Lionel Atheyne

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