On Mon, Dec 15, 2008 at 4:41 PM, Aadil V. [email protected] wrote:
Hi, I have read this information regarding the USRP ADC
“The full range on the ADCs is 2V peak to peak, and the input is 50 ohms
differential. This is equates to 40mW, or 16dBm.”
Please may someone enlighten me, how the 40mW and 16dBm values were
I am not sure where those numbers came from directly, but the 50 Ohms
differential might be wrong. From the datasheet here:
Page 2 shows the differential input resistance to be 200 Ohms with the
maximum differential input being 2Vp-p.
Regardless (and assuming the 50 Ohms), the equations are only Ohms Law
and conversion into dBm.
P = V^2 / R
P = 1.0V^2 / 50 Ohms
P = 20mW
Since there are two inputs, we double that to be 40mW of power used up.
10log10( P / 1mW )
10log10( 40mW / 1 mW )
Hope this helped.