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Clock Distribution Network

Irfan Awan
Prodigy 230 points
Other Parts Discussed in Thread: LMK00301, LMK04110, LMK00304, LMK00304EVM
Hi All,
We are working on development of IR UWB positioning system . This  system is similar to system presented  in  IEEE paper 
"UWB-based Local Positioning System from a small-scale Experimental Platform to a large-scale Deployable System"

In our system we have to distribute 26 MHz clock as reference clock among the four base station . 

Distance between two base stations is 10 meter. The clock will be distributed off broad  via twisted pair cable.

Can anyone please suggest  any suitable product from TI clock and timing product  for our solution.

Clock requirements 
26 MHz
+- 5 ppm







Kind Regards 


Irfan Awan


Marna Tech AB


Stockholm Sweden


Phone +46736160016 

								


				
				

				
			

		

			
						
									
                			    			                        
						
						
			
			
						
			                        
			
			
				
			  
			

			     
			

		


				    			

						
















	

	

					
    
	
    





		
	
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                          TI__Mastermind
                        32575 points
                      
    
                          
                   		
		
    
					
    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. 

    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.
      3. 

      

    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. 

    2. CTS 26 MHz TCXO: http://www.ctscorp.com/components/Datasheets/008-0324-0.pdf
      3. 

    

    Best regards,
    

    Alan
    

     
    

     
    

     
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    

	            
                 	
	
    
				
		                
                
                
                
                
                
                
        		
		
				
    
			
		
    
		
		 
		
		
     
    
	
    

    
			
    
			
    
		
    

		
    
	
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						in reply to Alan O
					
									
    
	
    
	                                    
                      
    
                        
                          Prodigy
                        230 points
                      
    
                          
                   		
		
    
					
    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
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    

	            
                	
	
    
				
		                
                
                
                
                
                
                
        		
		
				
    
			
		
    
		
		 
		
		
     
    
	
    

    
			
    
			
    
		
    

		
    
	
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                          TI__Mastermind
                        32575 points
                      
    
                          
                   		
		
    
					
    Hi Irfan,
    

    The LMK00301 10-output differential clock buffer can be ordered here: http://www.national.com/pf/LM/LMK00301.html#Boards.  As I mentioned before, a 4-output version of this device will be released soon.  Performance and functionality will be very similar.
    

    The evaluation board does not include the 26 MHz TCXO.  However, it does have a 3.2 x 2.5 mm footprint (Y2) for a SMD crystal, which could accomodate a TCXO in the same package.  You would need to disconnect the crystal Y1 and its load capacitors, and then install the TCXO with the proper connections.  TCXO pins 1 & 2 = tie to GND, pin 3 = Output ac-coupled to OSCin pin, pin 4 = tie to VCC with nearby bypass cap).
    

    I found a couple 3.3 V TCXOs in 3.2 x 2.5 mm footprint on Digi-key.
    


     Best regards,
    

    Alan
    

     
    

     
    

     
    

     
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    

	            
                 	
	
    
				
		                
                
                
                
                
                
                
        		
		
				
    
			
		
    
		
		 
		
		
     
    
	
    

    
			
    
			
    
		
    

		
    
	
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                          Prodigy
                        230 points
                      
    
                          
                   		
		
    
					
    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
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    

	            
                	
	
    
				
		                
                
                
                
                
                
                
        		
		
				
    
			
		
    
		
		 
		
		
     
    
	
    

    
			
    
			
    
		
    

		
    
	
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                          TI__Mastermind
                        32575 points
                      
    
                          
                   		
		
    
					
    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
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    

	            
                 	
	
    
				
		                
                
                
                
                
                
                
        		
		
				
    
			
		
    
		
		 
		
		
     
    
	
    

    
			
    
			
    
		
    

		
    
	
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