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Recommended differential voltage range between CLKIN+ and CLKIN- pins of LVDS/LVPECL-I/F based on Input power in HMC7043.

Question asked by SKBY on Dec 15, 2016
Latest reply on Dec 18, 2016 by SKBY

Dear Experts,


My customer is making LVDS interface design of HMC7043. Could you please reply to the following question?


Q1: According to Table 4 on the p.4 of HMC7043 datasheet,
"Recommended input Power, AC-Coupled, Differential" for CLOCK INPUT (CLKIN) is -6[dBm] to +8[dBm].


My customer asked me about the differential voltage range of the above CLOCK INPUT (CLKIN) with 100[ohm] internal resistance termination of HMC7043.


Let me show you the following understanding on the above question:


Pdin: Differential input power value at [dBm].
Vdin: Differential input voltage between CLKIN+ and CLKIN- pins at [V] with 100[ohm] resistance.


According to the Ohm law,
Pdin = 10xlog10(1000xVdin^2/100[ohm]).
---> Vdin = SQRT[10^{(Pdin-10)/10}].


Vdin = 158.5[mV] for -6[dBm] with 100[ohm] termination.
Vdin = 794.3[mA] for +8[dBm] with 100[ohm] termination.


Is the above understanding correct?


Thanks and regards.