need some recommendation to improve the output clock frequency of TIDA-01023

xiao peng ma

Other Parts Discussed in Thread: TIDA-01023, LMX2594

I want to use the same clock architecture in TIDA-01023 to achcieve JESD204B-synchronized clocks, but the output clock frequency is 10GHz.

Which RF synthesizer do you recommend?

over 3 years ago

0 Noel Fung over 3 years ago

TI__Guru* 81340 points

Hi Pengma,

LMX2594 already support >10 GHz RF output.

0 xiao peng ma over 3 years ago in reply to Noel Fung

Intellectual 640 points

Thanks for your reply.

Is there some test result about the clock skew when the output clock frequency is 10GHz?

0 Noel Fung over 3 years ago in reply to xiao peng ma

TI__Guru* 81340 points

Hi Pengma,

What clock skew you are talking about? Between the reference clock and 10GHz output of the synthesizer?

0 xiao peng ma over 3 years ago in reply to Noel Fung

Intellectual 640 points

The clock skew between the 10GHz output of the two LMX2594.

0 Noel Fung over 3 years ago in reply to xiao peng ma

TI__Guru* 81340 points

Hi Pengma,

That depends on the configuration, in idea case (e.g. Reference clock = 100MHz, RF output = 10GHz), the skew between two LMX2594 could be less than 1ns.

0 xiao peng ma over 3 years ago in reply to Noel Fung

Intellectual 640 points

Can LMX2594 SYNC pin be used to achieve better clock skew?

The clock skew of TIDA-01023 is only 8ps.

Here is another question.

If Reference clock = 100MHz, RF output = 10GHz, looking at LMX2594 datasheet Figure 27, SYNC category should be Category 1 - SYNC Mode Not required at all , No limitations on fOSC.

What does "SYNC Mode Not required at all" mean?

0 Noel Fung over 3 years ago in reply to xiao peng ma

TI__Guru* 81340 points

Hi Xiaopeng,

That means you don't need to enable the VCO_PHASE_SYNC bit.

0 xiao peng ma over 3 years ago in reply to Noel Fung

Intellectual 640 points

Sorry, maybe there are some misunderstandings about the 7.3.10 Phase Synchronization.

From 7.3.10.1 General Concept, I can assume that two LMX2594 can be synchronized by SYNC pin.

But below Figure 25, does "When the SYNC feature is enabled" mean "VCO_PHASE_SYNC = 1" ?

From 7.3.10.2 Categories of Applications for SYNC, I can assume that the usage of SYNC feature in TIDA-01023 is timing critical and SYNC pin must be used.

From Figure 27, what is the difference between "SYNC Required" and "SYNC Mode Required" ?

From 7.3.10.3 Procedure for Using SYNC, does "This procedure must be used to put the device in SYNC mode" mean that if I want to use SYNC feature, LMX2594 must be in SYNC mode(VCO_PHASE_SYNC = 1)?

From 7.3.10.4 SYNC Input Pin, I can assume that SYNC pin and VCO_PHASE_SYNC = 1 should be used together.

Sorry for so many questions.

0 Noel Fung over 3 years ago in reply to xiao peng ma

TI__Guru* 81340 points

Hi Xiaopeng,

In the bottom Cat.1 scenario, VCO_PHASE_SYNC is not necessary equal to 1. After normal programming, all the devices are in sync.

In the higher level Cat.1 scenario requires VCO_PHASE_SYNC = 1.

In Cat. 2, VCO_PHASE_SYNC is not necessary equal to 1. After programming all devices, send a SYNC pulse to the SYNC pin to get every device synced.

In Cat. 3, program the devices with VCO_PHASE_SYNC = 1, send a time-controlled SYNC pulse to synchronize all the devices.

0 xiao peng ma over 3 years ago in reply to Noel Fung

Intellectual 640 points

Thank you very much.

So you mean that in the bottom Cat.1 scenario, VCO_PHASE_SYNC = 1 and SYNC pin can also still be used to achieve phase synchronization like TIDA-01023?

Are there some test results about the clock skew between the RF output of the two LMX2594 based on TIDA-01023 when the output frequency is 10GHz?