AD9781 DAC Output Power vs. Nominal Power Figure

Hello KGhostW ,

Thank you for your interest in AD9781.

Figure 38 references the nominal output power at fundamental frequency across a 50Ω load. The peak to peak voltage across 50Ω should be within the output compliance range of -/+1V. 

Your computation of the output power is correct if the output current is DC however the measurement shown here is across frequency and also considers the inherent sinx/x response of the DAC on both Normal and Mix Mode. 

Kind Regards, 

Lorenz

Thank you, Lorenz for your reply.

So I have a better understanding of the expected DAC output power in the future, should I be using the RMS I_FS to account for frequency, or how can I more accurately account for frequency when calculating power?

I was using the RMS Voltage from the output compliance range of -/+1V with the assumption this would account for frequency. This does not result in the power reflected in Figure 38, even roughly accounting for the DAC's innate LPF response (Figure 65) in Normal mode operation.

Thanks again,

Thank you, Lorenz for your reply.

So I have a better understanding of the expected DAC output power in the future, should I be using the RMS I_FS to account for frequency, or how can I more accurately account for frequency when calculating power?

I was using the RMS Voltage from the output compliance range of -/+1V with the assumption this would account for frequency. This does not result in the power reflected in Figure 38, even roughly accounting for the DAC's innate LPF response (Figure 65) in Normal mode operation.

Thanks again,