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HMC920 EVB with HMC863ALC4 bias issue

Category: Hardware
Product Number: HMC920 EVB, HMC863ALC4 EVB

Dear Sir,

I am trying to test HMC863 along with HMC920 with the EVB. When I connect the default HMC920 EVB to my HMC863 board, the HMC863 is not functioning, and the VNEG and  VGATE are both staying at -2.4V.  Then I followed the application notes added a 255K resistor between VGATEB and VGATE to adjust the VGATE threshold around -0.8V. When I pullup SW and connect the PA again, VDRAIN stays at 0V and VGATE is still at -2.4V, it seems to me the HMC920 is not enabled. I am struggling how to use the HMC920 to bias HMS863. 

From my understanding, HMC920 should be auto adjust the VGATE from -2.4 to -0.8V until HMC863 Idd reach 360mA because I set the Idain to 360mA with Rsense to 480ohms. Am I wrong? do I need to adjust both VNEG and VGATE to around -0.8V?

Please help!

Thanks,

Dawen   

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