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Question about DAC3484EVM and TSW1400 EVM

Bowei Liu
Prodigy 60 points
Other Parts Discussed in Thread: DAC3484

Question: how to get desired waveform?

configuration file used by DAC3484EVM: DAC3484_FDAC983p04MHz_4xint_NCO_30MHz_QMCon_CDCE62005VCO.txt

Self clocking, 983.04M, 4x interpolation

Data generation card: TSW1400EVM

data_file: WCDMA_TM1_complexIF30MHz_Fdata245.76MHz_1000.tsw   (245.76 * 4 = 983.04, that is why I choose this data rate)

data rate: 245.76M symbols per second, 2's complement.

(Please tell me whether I selected the right test data file?)

but the spectrum shows that i got several bands at different frequencies. 

One band centered at 61.4M, one band centered at 184.40M, one band centered at 307.60M, there are more at higher frequencies

I simply want to get one band centered at 30M.

My question is, what should I do to get the correct waveform?

To make project go on, I disable mixer. I feel that is not the right way, but that is one way for me to get the waveform like what it shows on HSDS pro FFT result.

I am student not familiar with analog engineering. The configuration of DAC3848EVM is really hard for me. 

Thanks,

Bowei Liu

  • 0
    TI__Genius 9695 points

    Hi Bowei,

     

    Aside turning off the NCO, you should also disable the mixer and QMC feature in the DAC. Use the attached configuration file where I have already done this.

    Fullscreen 2728.DAC3484_FDAC_1228p8MHz_4xint_NCOoff_QMCoff.txt Download 
       x00	   xF284
   x01	   x0100
   x02	   x8002
   x03	   xA001
   x04	   x4DF1
   x05	   x0000
   x06	   x3400
   x07	   xFFFF
   x08	   x0000
   x09	   x8000
   x0A	   x0000
   x0B	   x0000
   x0C	   x0400
   x0D	   x0400
   x0E	   x0400
   x0F	   x0400
   x10	   x0000
   x11	   x0000
   x12	   x0000
   x13	   x0000
   x14	   x0000
   x15	   x0640
   x16	   x0000
   x17	   x0640
   x18	   x205F
   x19	   x10F0
   x1A	   x8820
   x1B	   x0800
   x1C	   x0000
   x1D	   x0000
   x1E	   x1111
   x1F	   x8882
   x20	   x2400
   x22	   x1B1B
   x23	   x001F
   x24	   x1000
   x25	   x787A
   x26	   xB6B6
   x27	   xEAA8
   x28	   x4541
   x29	   x1A1A
   x2A	   x1616
   x2B	   xAAA2
   x2C	   xC4C4
   x2D	   x0004
   x2E	   x0000
   x2F	   x0000
   x30	   x6020
   x7F	   x0001
CDCE62005 Registers
Freq:0.000000MHz
Address	Data
00		80400000
01		813C0001
02		81400002
03		C1040003
04		00040004
05		29F01A55
06		44AF0006
07		165294A7
08		20001808

    Thanks,

    Eben.

  • 0 in reply to Ebenezer Dwobeng
    Prodigy 60 points

    Hi Eben

    Thanks for your answering. Your answer helps me a lot. 

    I loaded your configuration file. This file seems to be using external clock. Is that right?

    Do you have configuration file which uses internal VCO to clock DAC to work at 1228.8 M Hz?

    The example files provided can only reach 983.04M Hz.

    Thank you