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HMC197B Recommended for New Designs
The HMC197B(E) is a low-cost SPDT switch in a 6-lead SOT26 plastic package for use in general switching applications which require very low insertion loss...
Datasheet
HMC197B on Analog.com

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HMC197B switching rate

		
	
				

			

									
					    martin.schle
					
							

            
            			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on May 12, 2017 
				
			
			
		
    
		
		                     
				
        		
    
		    
		    		    
		    			
    
			    
    Hello,
    
 
    for an academic research project I need a very fast RF switch with low insertion loss in order to modulate (On/Off keying) a 2.4GHz carrier. The HMC197 switch seems to be a good fit for this job as it shows an IL of 0.4dB and a rise/fall time of 3ns.
    
 
    However, I am not quite sure what would be the maximum switching rate that can be achieved with this switch. Is it 1/(tON+tOFF) = 50MHz? In addition, there is only a typical value given for the switching speed characteristics.
    
 
    Also, I wonder whether the maximum input power for hot switching (20dBm) has to be reduced further when it comes to switching with a high rate (say, 20MHz).
    
 
    Please note that since this is for academic research an not for production, it's OK to push the device to it's limits.
    
 
    I would be grateful for any advice you might be able to give me.
    
 
    Best regards,
    
 
    Martin
    
			
    
			
									
		                             
                        

    
    
                                            
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                on May 16, 2017 4:02 PM
            
            
						
			            		
        
		
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        Hi,
        
 
        thank you very much for your answer, it is very helpful.
        
 
        Still, I dare to add two more questions:
        
 
        I'm a bit puzzled by the datasheets of HMC197B & HMC221B:
        
 
        The HMC197B one says:
        
 
          
  
        • See HMC221B(E) for same performance in an alternate SOT26 pin-out.
          • 
  
        • Insertion loss: DC - 2.5 GHz: 0.4dB (typ) 0.9 (max)
          • 
 
        
 
        The HMC221B one says:
        
 
          
  
        • Insertion loss: 2.5 GHz to 3.0 GHz: 0.8 dB (typ), 1.1 dB (max)
          • 
  
        • But the "typical characteristics" plot clearly shows an IL below .5dB for the full range 2.5 GHz to 3.0 GHz
          • 
 
        
 
        These statements don't really go together.
        
 
        Since the pinout of HMC221B is actually better suited for my layout, I wonder now whether HMC197B really has the better performance in terms of insertion loss.
        
 
        The second question is whether there is a good way to simulate the transient behaviour of the switches, since the S-parameters are probably of no use for may application.
        
 
        Again, thanks a lot!
         
        
			
        

		
			
	      

		
		
	
        
	
        
		
        
			
		
        
	
        
	
        
		
						
						
				
						
				
				
		
		
        
			
		
        
	
        

        

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