Hi

I am currently doing development optical power meter with ADL5304.

Initial design and testing is done well But i met following issue.

"I can't calculating or coverting voltage(Vout) to dBm for optical power measuring."

**Can you advice me how i can calculating Vout level to dBm?**

I am waiting for your advice and support.

Cheers!!!

The ADL5304 is a current responding device with a typical transfer function like that shown in Figure 3. This is modeled by the equation 7 in the datasheet, which is Vlog = 0.2*log10(Ipd/3.162fA).

The photodiode that you use will have some responsivity, rho, with units of Amps/Watt. Using rho, you can get the current produce by the photodiode when X Watts are impinged upon it.

To convert from dBm to Watts, use the equation: Power (Watts) = 10^(X_dBm/10)/1000, where X_dBm is your dBm number.

If the intercept power (in Watts) were related to the intercept current by Iz = rho*Pz and the photodiode current related to the power (in Watts) impinged on the PD, where Ipd = rho*Popt, then the whole transfer function becomes:

Vlog = 0.2*log10(10^(X_dBm/10)/1000)/Pz)

Most of this in on page 17 of the ADL5304 datasheet.