HACKRF

Question

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

enash · Accepted Answer

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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