# To estimate PA max drain current(ID)

Hi,

I am designing power for PAs and I have a problem.

When I look into HMC8500 datasheet, it only tell me about the quiescent like 28 V at 100 mA.

But when I design the power, I need to provide the sufficient current. So I need to know the ID_max of HMC8500 which cannot be found in the datasheet.

So I decide to estimate that by myself, but I am not sure the way how I calculate is correct.

1) When the Pout_sat is 10W when input RF is 1W, so the added power is 9W.

2) The PAE is 55%, so the power supply should be 9W/(55%)=16.37W.

3) The VD is 28V, so the ID is 16.37W/28V=584mA.

Is that correct to estimate the max current requirement of HMC8500?

## Top Replies

• Hi avatarofcliff,

The IDD at Psat is in the data sheet. See Figures19, 22, 23, 26. THE plots contain Pout, Gain, PAE & IDD vs. input power. The current consumption at Psat is ~ 800 mA.

Regards,

Jim B

• Thank you for telling me how to find the correct information from datasheet.