DAC34H84: Deferent the Ouput Delay both 4 Chenel.

Louis Han15

Genius 4680 points

Part Number: DAC34H84

hello

There is a delay of up to 20ns difference in the output for use Real Mode.

But I'm not found the Parameter for Delay between channels

Please Check the this issue.

DAC34H84 Register Setting Value

/** Initialize register **/

DAC34H84WriteRegister(0X00, 0x019F);

DAC34H84WriteRegister(0X01, 0x010E);

DAC34H84WriteRegister(0X02, 0x00F2);

DAC34H84WriteRegister(0X03, 0x001);

DAC34H84WriteRegister(0X04, 0x0000);

DAC34H84WriteRegister(0X05, 0x0000);

DAC34H84WriteRegister(0X06, 0x0000);

DAC34H84WriteRegister(0X07, 0xFFFF);

DAC34H84WriteRegister(0X08, 0x0000);

DAC34H84WriteRegister(0X09, 0x8000);

DAC34H84WriteRegister(0X0A, 0x0000);

DAC34H84WriteRegister(0X0B, 0x0000);

DAC34H84WriteRegister(0X0C, 0x0400);

DAC34H84WriteRegister(0X0D, 0x2000);

DAC34H84WriteRegister(0X0E, 0x0400);

DAC34H84WriteRegister(0X0F, 0x0400);

DAC34H84WriteRegister(0X10, 0x0000);

DAC34H84WriteRegister(0X11, 0x0000);

DAC34H84WriteRegister(0X12, 0x0000);

DAC34H84WriteRegister(0X13, 0x0000);

DAC34H84WriteRegister(0X14, 0x0000);

DAC34H84WriteRegister(0X15, 0x2000);

DAC34H84WriteRegister(0X16, 0x0000);

DAC34H84WriteRegister(0X17, 0x2000);

DAC34H84WriteRegister(0X18, 0x0000);

DAC34H84WriteRegister(0X19, 0x0000);

DAC34H84WriteRegister(0X1A, 0x0020);

DAC34H84WriteRegister(0X1B, 0x0000);

DAC34H84WriteRegister(0X1C, 0x0000);

DAC34H84WriteRegister(0X1D, 0x0000);

DAC34H84WriteRegister(0X1E, 0x1111);

DAC34H84WriteRegister(0X1F, 0x8882);

DAC34H84WriteRegister(0X1F, 0x8880);

DAC34H84WriteRegister(0X20, 0x2201);

DAC34H84WriteRegister(0X22, 0x1B1B);

DAC34H84WriteRegister(0X23, 0xFFFF);

DAC34H84WriteRegister(0X24, 0x0000);

DAC34H84WriteRegister(0x25, 0x7A7A);

DAC34H84WriteRegister(0x26, 0xB6B6);

DAC34H84WriteRegister(0x27, 0xEAEA);

DAC34H84WriteRegister(0x28, 0x4545);

DAC34H84WriteRegister(0x29, 0x1A1A);

DAC34H84WriteRegister(0x2A, 0x1616);

DAC34H84WriteRegister(0x2B, 0xAAAA);

DAC34H84WriteRegister(0x2C, 0xC6C6);

DAC34H84WriteRegister(0x2D, 0x0004);

DAC34H84WriteRegister(0x2E, 0x0000);

DAC34H84WriteRegister(0x2F, 0x0000);

DAC34H84WriteRegister(0x30, 0x0000);

DAC34H84WriteRegister(0x7F, 0x0001);// Alarm Check Register( Addr = 0x7F , Data 0x5409 )

/* Curio(20170713) Request kissyun */

DAC34H84WriteRegister(0x02, 0x00D2);

DAC34H84WriteRegister(0x03, 0x4001);

Regards.

over 5 years ago

0 Louis Han15 over 5 years ago

Genius 4680 points

hello
I wait your feedback.
Please Check the My question.
Regards.

0 Kang Hsia over 5 years ago

TI__Guru 66184 points

Hello Louis,

Sorry, we had US Thanksgiving Holiday so the response was delayed.

The DAC34H84 by design and also by lab verification that all four channels are synchronous.
Since you are using real input mode (not complex), you should not be using the complex mixer with NCO.
Please set 0x02 register to 0x00E2 to disable the complex mixer with NCO. Using the NCO will cause the real data to mix with each other due to the nature of the complex mixer.
Using Fs/2 mixer is acceptable for real data (i.e. 0x0D = 0x2000).

You may want to check again by disabling the fs/2 mixing process also
i.e. 0x0D = 0x0000
0x02 = 0x00A2

-Kang

0 Louis Han15 over 5 years ago in reply to Kang Hsia

Genius 4680 points

Hi Kang

Thanks for your support

My Customer Used this Condition.

- Input data rate = 122.88Msps

- DAC Clock = 245.76MHz

- Interpolation = x2

- Real Channel Upconversion, Fs/2 Mixer, Mixer Enable, NCO Enable

- Input data(122.88Msps, fc = -30.72MHz) -> x2 -> Fs/2 Mixer(122.88MHz) -> DAC output -> IF fc = 92.16MHz

Mixer and NCO is Enable.

Please Check the condition.

Regards.

0 Kang Hsia over 5 years ago in reply to Louis Han15

TI__Guru 66184 points

Louis,

for real mode, they can only use fs/2 mixer. They cannot use NCO as this will mix the two real data into one stream of data. This is not the expected operation for real data input.

-Kang

0 Louis Han15 over 5 years ago in reply to Kang Hsia

Genius 4680 points

Hi Kang

My customer Tested after NCO Disable.(0x02 = 0xD2)

but Test results did not change.

DAC REG(0x02)	P0(us)	P1(us)	P2(us)	P3(us)	Deviation(ns)
E2	-0.008	0	-0.012	-0.005	12
D2	-0.008	0	-0.012	-0.005	12

when you tested it , was not there any Defersent the Ouput Delay both 4 Chenel?

Regards.

0 Kang Hsia over 5 years ago in reply to Louis Han15

TI__Guru 66184 points

Hi,

No, I did not see any delay difference. The only other thing is if the customer is testing on the EVM, the different output channel may have different 180* inversion due to layout optimization of p/n leg of the DAC output

This may explain a fixed delay at a particular frequency.

-Kang

0 Louis Han15 over 5 years ago in reply to Kang Hsia

Genius 4680 points

Hi Kang

Thanks for your support.

I attached the Schematic file for DAC34H84.

Please check the schematic for any delay difference.

Regards.

0 Kang Hsia over 5 years ago in reply to Louis Han15

TI__Guru 66184 points

Hi Louis,
I see DAC_OUT1 and DAC_OUT3 have the same phase, and DAC_OUT2 and DACOUT4 have the same but inverted compared to DAC_out1/3.
This could explain if the customer is comparing DAC_OUT1 with DAC_OUT2, they can seeing the inverted phase.

Perhaps they can check the DAC_OUT1 with DAC_OUT3 to eliminate the phase inversion.

-Kang

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DAC34H84: Deferent the Ouput Delay both 4 Chenel.