See questions at the bottom of post regarding the response below
The data sheet states that the buffered baseband outputs are capable of driving a 2V p-p differential signal into a 200 ohm load. My question is, what input power level at the RF input does 2Vptp output correspond to? If I start out at 0 dBm at the RF input, and apply 7 dB of gain, I will see +7 dBm at the I and Q outputs combined, or +4 dBm at each output. +4 dBm converts to 2.0044 volts ptp across 200 ohms. Is that correct? Does 2Vptp on each output (I and Q) correspond to 0 dBm at the input?
Next question relates to IP1dB which is spec’ed at 11.6 dBm. What voltage (cross 200 ohms) comes out of the part with +11.6 dBm applied to the RF input?
Questions regarding the above response:
- 1. I tried to verify the “Working backwards” calculation below, to determine input power with 2Vptp at the output. I arrived at the same 0.893Vpp value but when converting to power, I get 2 milliwatts of +3 dBm. Where does the 2 dBm figure below come from? Just a typo or am I missing something?
- 2. At P1dB, the differential output voltage can reach 4.8Vpp, If the device is only capable of driving 2Vptp at the output, how is P1dB measured? How would we go about verifying P1dB if we had to do it?
- 3. Can the device be driven single-ended? (data sheet suggests that it can, but recommends differential drive through as balun). If the device is driven single-ended both at the LO and the RF input, what specifically is the performance penalty?
- 4. The data sheet shows performance at 19.GHz, 2.7 GHz, 3.6 GHz, and 5.8 GHz. Is there any specific problem at 5 GHz that we should know about? How do we predict 5 GHz performance from the supplied data? Simple interpolation? Use 5.8 GHz data?
- 5. The device is designed to output 2V ptp into a 200 ohm load. My application requires 1Vptp into a 100 ohm load. What is the best way to provide this?