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:**

Where,

**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}].

So,

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.

Hi,

Your calculations are correct for a square wave. These values are mainly measured with sinusoidal signal. For this reason it is better to use 200mVpp (~=158.5 x sqrt(2)) for minimum limit. Similarly the maximum voltage level can be considered as 1.2V.

Regards,

Kazim