Hello,

My customer asks some questions about HMC721LP3E operation.

They say that they want to know whether the input swing level (VIH / VIL) of HMC721LP3E affects the output swing level (VOH / VOL) or not (even though the supply voltage and VR voltage level aren't changed.).

Please refer below their test result and let me know your opinions.

They changed only input level from (-1V ~ 1V) to (-0.2V ~ 0.2V) and output swing level was changed as below.

- VIH = 1V / VIL = -1V => VOH = 1.16V / VOL = 585mV
- VIH = 0.2V / VIL = -0.2V =>

(Simulation result : VOH = 963mV / VOL = 671mV, Proto board measure result : VOH = 90mV / VOL = 680mV)

Q1) Would you clarify whether output swing level of HMC721LP3E is influenced by input swing level or not?

Q2) Would you let me know correlation formula if there is any correlation formula existed between input swing level and output swing level?

Please advise me.

If you have any questions, please let me know.

Regards,

Se-woong

Hello,

I receved answers about these questions from cic.asia.

Please refer below answers.

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They changed only input level from (-1V ~ 1V) to (-0.2V ~ 0.2V) and output swing level was changed as below.

ADI: First of all this is not a linear amplification and the customer should not expect a linear change on the output when they change the input, usually when input voltage is decreased, rise time fall time and eye performances deteriorate.Regardng the questons, I am assuming that they are biasing the IC with Vee=-3.3V. (If they use another supply voltage, can you please specify?) .Lets also try not to forget that this is a logic circuit so if they can give more information about their experiment it would begood. Since this particular IC is XOR gate, specifying both input would be good.

ADI:This driving level is too much. CML input drive should be between -10mV and -550mV. If they repeat the experiment withthese voltages(VIH=-10mV, VIL=-550mV) they can see the output VOH=-10mV and VOL=-550mV. This is the standard operation. Driving the input with +1V may damage the IC, and in simulation it might not give accurate results.

(Simulation result : VOH = 963mV / VOL = 671mV, Proto board measure result : VOH = 90mV / VOL = 680mV)

Q1) Would you clarify whether output swing level of HMC721LP3E is influenced by input swing level or not?

ADI : The output swing can be mainly controlled with VR pin. It is also dependent to input but as I say, it is not a linear operation. If the customer can give more information, it would help more. What is the driving source of HMC721?Q2) Would you let me know correlation formula if there is any correlation formula existed between input swing level and output swing level?

ADI: It would not be a proper engineering approach since the correlation formula would be highly nonlinear and it canchange from part to part.

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Regards,

Se-woong