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HMC409 Recommended for New Designs
The HMC409LP4(E) is a high efficiency GaAs InGaP HBT MMIC Power amplifier operating from 3.3 to 3.8 GHz. The amplifier is packaged in a low cost, leadless...
Datasheet
HMC409 on Analog.com

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					    Wenjie0476
					
							

            
            			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Jul 16, 2025 
				
			
			
		
    
		
		                    	    
    
        	    
    Thread Summary
    
                The user is experiencing lower than expected output power (24.5 dBm) with the HMC409LP4E at 3.6 GHz and 4 dBm input power. The final answer suggests checking the power supply, ensuring it can source up to 1 Amp, and verifying the correct VCC and VBIAS voltages. A power sweep test is recommended to diagnose the issue further.
                        	    
    
                
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    Category: Hardware
    
    		        		            		    
    Product Number:  HMC409LP4E, HMC409 
    
    		        		    		    
    
		    		    
		    			
    
			    
    Hi ADI engineer
    

    I use the HMC409LP4E for RF_TX, the frequency is 3.6GHz, the power of RFIN is 4dBm,but the power of RFOUT only 24.5dBm.
    

    I try to reduce the RFIN power to -10dBm, Gain can up to 29dB.
    

    I find the Gain is 31dB,P1dB is 30.5dBm RFIN_MAX is 10dBm in datasheet. So i think the RFOUT can up to 30.5dBm
    

    But RFOUT only 24.5dBm,the gain only 21.5dB(24.5-4) when RFIN at 4dBm.
    

    Is there some wrong in my design? or I misunderstood？
    

    

    Thanks
    
			
    
			
									
		                             
                        

    
    
                                            
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      •  Analog Employees  
      
            
						
                            
            
            				
            
                on Jul 16, 2025 10:39 AM
            
            
						
			            		
      
		
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      Hi Wenjie,
      yes, you are getting much lower output power than expected. Are you using the evaluation board for the HMC409 or did you design your own circuit. Not that in order to get the performance specified in the datasheet, you need to use the recommended matching components. 
      To better diagnose the problem, it would be good if you do a power sweep. So apply the following power levels: -20, -16, -12,-8,-4,0,+4,+8 dBm. Then measure the gain, supply current and output power.  Note that your power supply need to be able to source approximately 1 Amp when the output power is at saturation (i.e. Pin=+8). Is it possible that this is the problem, that is, your power supply is not delivering enough current (the 615mA Spec in the datasheet is quiescent current, that is, current flowing when the part is turned on but no current is flowing). 
      Also, make sure that there is 5V on VCC1, VCC2, VBIAS and VPD as shown in the application circuit in the datasheet.
       
      
			
      

		
			
	      

		
		
	
      
	
      
		
      
			
		
      
	
      
	
      
		
						
				
						
				
				
				
		
		
      
			
		
      
	
      

      

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                on Jul 16, 2025 11:40 AM
            
            
						
			            		
        
		
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        Hi Enash
        

        thank you.
        

        I do not have the evaluation board. i try to design a PCB board that refer to datasheet as below, i use the recommended components.
        

        I used a digitally power for HMC409，the current limited at 1.2A. But HMC409 power on current is only 506mA when 5V on VCC1,VCC2,VBIAS and VPD.
        

        Can I adjustment the L3 value?
        

        thank you
        

         
        
			
        

		
			
	      

		
		
	
        
	
        
		
        
			
		
        
	
        
	
        
		
						
						
				
				
				
				
		
		
        
			
		
        
	
        

        

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