AD8336 Error from Ideal Line dB

[chandlerbing65nm]

Hello folks,

Need your help again. I need help on understanding the test method for calculating the Error from Ideal Line of AD8336.
Here's a snapshot of the test method.

1. where can i get the IDEAL_VGA_SLOPE and IDEAL_VGA_INTERCEPT values?
2. The test circuit that I will use, is this it?

I also attached the AD8336 Datasheet for reference.

Regards,
Chandler

 

[danadakk]

Slope is the G you are evaluating at....

Intercept value is DC offset .....? Not sure but thats what I think it is.

The test circuit shown would make sense if you are evaluating over freq.


Regards, Dana.

 

[stenzer]

Hi,

I assume your IDEAL_VGA_SLOPE is the AD8336 amplification which is stated on page 21

G_dB = V_gain \[\cdot\] 50 dB/V + 4.4 dB,

and inputs are your VGA gain setting voltage values.

I do not know what your IDEAL_VGA_INTERCEPT should be, but it seems it is related to the Composite Gain (page 21, and see third paragraph on page 20 in section VGA)

G_comp_dB = G_preamplifier_dB + (V_gain \[\cdot\] 49.9 dB/V) + 4.4 dB.

So it seems your IDEAL_VGA_INTERCEPT is the preamplifier gain which is

G_preamplifier_dB = 20 \[\cdot\] log(G_preamplifier_linear).

greets