Clock Distribution Network

7206.LMK04110_26MHz-TCXOref_26MHz-LVPECLout.savHi Irfan,

What are you phase noise or jitter requirements with integration bandwidth?

Based on the frequency accuracy requirement, you'll at least need a TCXO as your reference clock.  Depending on your phase noise/jitter requirements, you could consider the following approaches:

1. If you can find a 26 MHz, +-5 ppm TCXO that already meets your phase noise/jitter requirements, then you could use a low-noise clock fanout buffer/level translator with differential outputs for driving a twisted-pair cable.  One example is the LMK00301, which has 2 banks of 5 differential outputs (LVPECL/LVDS/HCSL) and universal inputs (single-ende/differential).  A 4-output version of this device will be available soon.
2. If you need better phase noise at higher offset frequencies (e.g. > 50 kHz), then you could use a TCXO as a reference clock to feed a clock jitter cleaner.  One example is to use the LMK04110 (5 LVPECL outputs) with the TCXO feeding the reference input to PLL2, which uses an integrated low-noise VCO with better high-offset phase noise than the TCXO.  The output divider has a very low broadband phase noise floor of about -160 dBc/Hz.
1. Attached is a simulation file for National's Clock Design Tool, which shows the LMK04110 configuration with PLL2 only (PLL1 not used) and an example 26 MHz TCXO reference.  The 26 MHz TCXO phase noise was modeled using the 10 MHz phase noise plot in the datasheet below, with the phase noise scaled up by +8 dB (=20*log10(26 MHz/10 MHz) ).
2. CTS 26 MHz TCXO: http://www.ctscorp.com/components/Datasheets/008-0324-0.pdf

Best regards,

Alan

Hi Alan,

Thanks for your reply.

We are using  four channels of IEEE802.15.4a  which are ch1.ch3.ch4.ch7 with center frequencies 3494.4 ,3993.6,4492.8 and 6489.6 MHz respectively  . 

Large channel spacing and spectral mask relax Phase Noise requirements for PLL.

Sorry I do not have exact number about Phase Noise .

What you suggest still the solution you proposed will be valid ,

Can you suggest any evaluation board which have both TCXO and Buffer.

Regards

Irfan

Hi Alan,

I was waiting for 4-output version of LMK00301 device. I guess LMK00304 is that . I try to order that online by Mouser . The shipping time to Sweden was 8 weeks.

We want  the evlation board for LMK00304 in 2 week , Can you please tell any alternative ? Like placing order directly to TI or any other solution.

Regards

Irfan Awan

Hi Irfan,

You can order the LMK00304EVM directly from TI via the tool folder: http://www.ti.com/tool/lmk00304evm

Just click the "Order Online" button.  You will need to be logged in to your ti.com account.  The user guide is available here.

The LMK00304 datasheet and IBIS model is available from the product folder: http://www.ti.com/product/lmk00304

Best regards,
Alan