Navassa Reference Clock

Question

The datasheet shows some black out zone for the reference clock, however, when I use Navassa eval board, I can inject external device clock frequencies in the middle of these black-out zones, such as 25.6MHz, 38.4MHz and the device is working good. 
 May I know what is limited by these dead zone? And when I use a external device clock in the middle of these dead zones, the transceiver is working in a reliable status or marginal status? Will there be noticeable degradation if there are power voltage change or ambient temperature change?

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RahulMushini · Accepted Answer

Hi Iwang, 
 Please find the latest ADRV9001 System Development User Guide: https://www.analog.com/media/en/technical-documentation/user-guides/adrv9001-system-development-user-guide-ug-1828.pdf 
 I believe you may have mixed up Device Clock and Arbitrary Sample Rate. 
 The Arbitrary Sample Rate(ASR) refers to the data port sample rate which you can find out in the device configuration tab. ASR mode supports an almost continuous range of rates up to 61.44 MHz , with a list of dead zones mainly due to the limitations in the decimation/interpolation rate supported in the datapath. There are certain frequency which might be in the dead zone for instance 51.2MHz when using the default system clock. There is however an option in the TES to change the system clock that will work to get the 51.2MHz sample rate. In the Device Configuration tab select the Custom Extended Setup option.

This allows the system clock to run as low as 150MHz, this changes some of the dead zones and for example the 51.2MHz is a viable option with this setting. Again the best way to find out what frequencies will work here is to use the TES. Trying out any data port sample rate in TES will show if it is possible or not. If a sample rate (or configuration more generally) is valid, it will return with a valid light in the traffic light indicators in the 'Device Configuration' page. 
 
 Coming to the Device Clock input which can find it in the Clock tab in TES, which has no dead zone frequency. The frequency can be supplied to Device clock is upto 1GHz (refer to datasheet Table 3) 
 
 Note: The wide band Dead zones frequency is in MSPS but in user guide its written as kSPS, this will be rectified in the next user guide release. 
 
 Regards 
 Rahul)

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