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HMC435A Recommended for New Designs
The HMC435AMS8G(E) is a non-reflective DC to 4 GHz GaAs MESFET SPDT switch in a low cost 8 lead MSOP8G surface mount package with exposed ground paddle...
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HMC435A on Analog.com

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Inquiry About External Capacitor on HMC435 RF Switch (Pins 1, 2 - A, B)

		
	
				

			

									
					    DanamSystems
					
							

            
            			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Apr 7, 2025 
				
			
			
		
    
		
		                     
				
        		
    
		    
		    		    
    
		      		            		        
    Category: Datasheet/Specs
    
    		        		            		    
    Product Number:  HMC435A  
    
    		        		    		    
    
		    		    
		    			
    
			    
    I am currently reviewing the datasheet for the HMC435 RF switch and I have a question regarding pins 1 and 2 (A and B). In the simplified schematic provided in the datasheet, it shows that a capacitor is connected in parallel with these control pins. However, I could not find any recommended value for this capacitor in the datasheet.
    

    Could you please clarify:
    

      

    1. 

      Is this external capacitor (C) required for typical operation?
      

      2. 

    2. 

      If so, what is the recommended capacitance value or range?
      

      3. 

    3. 

      Are there any application-specific conditions under which this capacitor should be included?
      

      4. 

    

    Thank you very much for your support.
    
			
    
			
									
		                             
                        

    
    
                                            
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      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Apr 7, 2025 4:50 AM
            
            
						
			            		
      
		
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      Hello,

      The capacitor you refer (pin 1 and pin2) is shown in the pin description table. 
      The R and C shown in interface schematic is the model of what's seen inside the chip. In other words, the capacitor is an internal element of the chip. 
      You don't need additional (external) capacitor. On the other hand, we recommend series 100-ohm resistor on control lines (A and B) as shown in evaluation board. 
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
				
						
				
				
				
		
		
      
			
		
      
	
      

      

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