LMH6505: LMH6505 gain temperature coefficient

Hello Kent,

   This formula does not relate to gain changing with temperature as you have shown in Figure 1. Rather, this formula refers to how the theoretical gain could be compared to the actual gain measured at a certain Vg. K in this context refers to the gain multiplier, rather than a temperature coefficient, which is given as a spec in the electrical characteristics table. The components within the exponential is meant to represent the error function for a Vg range. This is meant to be modeled as a "best fit line" for the typical gain shown in Figure 42. If you would like to know how gain changes over temperature, you should refer to the typical performance characteristics plots that note temperature (such as Figure 4 and 10) as well as the figure you have attached to your post, Figure 1. 

Thank you,

SIma

Hi Sima,

Thank a lot for you reply, it is very helpful, but I still be confused something,

#1,  The theroretical gain forum include Vc factor, Vc is 79mV at room temperature, what voltage is Vc at other temperature?

#2, For Fig10, index the gain change with temperature, right? But vertical axial is S21, what mean?

#2, 

Best Regards,

Kent

Hello Kent,

   Unfortunately, we are unsure of the Vc measurement at other temperatures; since, it seems like the number was derived to model the typical gain at only room temperature. This can be seen in Figure 42 as one trend for one temperature. S21 refers to the s-parameters of a two port network analyzer to measure reflection/transmission characteristics received at port 2 relative to port 1, with the setup shown in the figure below. Generally it refers to the forward voltage/power gain, but in this case it is the gain control (magnitude and phase). 

Thank you,

Sima