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HMC8205 Recommended for New Designs
The HMC8205BF10 is a gallium nitride (GaN) broadband power amplifier delivering 45.5 dBm (35 W) with 38% power added efficiency (PAE) across an instantaneous...
Datasheet
HMC8205 on Analog.com

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hmc8205BF10 Biasing Sequence

		
	
				

			

									
					    Mihirrr
					
							

            
            			
				
									
											
			
			
				
			
			
			    	
			                    
                
				                on Oct 13, 2025 
				
			
			
		

		
		                    	    

        	    
Thread Summary

                The user is concerned about applying VDD to the HMC8205BF10 power amplifier after measuring a drain-to-source resistance of 10 Ω with a -8 V gate voltage. The final answer suggests carefully turning on the device by setting the power supply to 0V, applying an initial current limit of 650mA, connecting the VDD pins in parallel, setting the gate voltage to -4V, and gradually increasing the supply voltage to 28V while monitoring the current to ensure it does not exceed 500mA.
                        	    

                
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Category: Hardware

    		        		            		    
Product Number:  hmc8205BF10, hmc8205 

    		        		    		    

		    		    
		    			

			    
Hey,


For biasing the HMC8205BF10 power amplifier, I’m following the steps given in the datasheet. When I apply a gate voltage of –8 V, I measure a drain-to-source resistance of about 10 Ω. Should I apply VDD now, or is it risky since the PA costs $800?

			

			
									
		                             
                        

    

                                            
                 hardware
                
                                                    
                 biasing
                
                                                    
                 rf & microwave
                
                                                    
                 hmc8205
                
                                                    
                 power amplifiers
                
                                        
                                            
                
                
                                        
                                            
                
                
                                
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    •  Analog Employees  
    
            
						
                            
            
            				
            
                on Oct 14, 2025 5:50 PM
            
            
						
			            		
    
		
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    It's definitely prudent to be careful with turn-on of this device. 
    

    

    

    

    Are you working with a loose HMC8205BF10 or an evaluation board?  I'm going to suggest that you turn on the chip/board very carefully using the following steps. 
    

      

    1. 

      Set the power supply voltage to 0V.
      

      2. 

    2. 

      Set an initial current limit on the power supply current at 650mA. 
      

      3. 

    3. 

      Connect the (0V) supply voltage to the three VDD pins in parallel.  
      

      4. 

    4. 

      Set the gate voltage to -4V.
      

      5. 

    5. 

      Start increasing the supply voltage. It should not go above 500 mA (see Fig 50 in datasheet)
      

      6. 

    6. 

       Continue increasing the supply voltage to 28V. It should still be no more than 500mA.
      

      7. 

    7. 

      Start increasing VGG, making it more positive, until the target quiescent current is reached.  
      

      8. 

    

    

    

    

    

    

    

    

    

    

    

    

    

    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
				
				
				
		
		
    
			
		
    
	
    

    

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    •  Analog Employees  
    
            
						
                            
            
            				
            
                on Oct 30, 2025 3:08 PM
            
            
						
			            		
    
		
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    I have not heard back from you so I'm assuming that you do not need further assistance. 
    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
						
				
				
				
		
		
    
			
		
    
	
    

    

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