I tried to dc sweep V3 in my circuit and measure the gain. But it does not give a correct result.
What I am trying to do is actually recreating some measurements from the datasheet.
Maybe there is a simulation techniques that I do not know yet. Appreciate any suggestion.
According to the Datasheet of the AD8337 (Rev. D), page 21/28 under section Gain control considerations:
The offset voltage effect of the AD8337, as with all VGAs, can appear as a complex waveform when observed across the range of VGAIN voltage. Generated by multiple sources, each device has a unique offset voltage (VOS) profile while the GAIN input is swept through its voltage range.
At least from what I can understand, you're seeing the influence of \$V_{GAIN}\$ on the offset voltage, which directly affects the output voltage as well.
I seem to be getting something pretty close to the datasheet:
but I had to probe immediately after the pin for the output (V(x)), otherwise there would have been some 18 dB missing (V(o)). The input is also a more meaningful 0.1 V (accounted for in the plot window as *10). Another thing that's corrected from your schematic is the proper use of an input resistance: you placed it across the voltage source, which is useless, instead of in series. I also didn't use LC filtering since the only noise here is the double residuals. The symbol is the generic [Misc]/DIP8, for the lack of one, but the pinout is the same. Also, in your waveform window, did you use log minus log? The correct way is 20 * log10( V(out) / V(in) ).
