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LMH6503 Max Gain for Vs= +/- 3,3V

Hi guys!
Is the EQUATION 3 (the equation for the Gain) changes for a double supply of +/- 3,3 V in the LMH 6503?

The datasheet  say :   Av = RF/RG * 1,72 * [(VG+1)/2]   for -1<VG<+1,    [EQUATION 3]

 but it say also that  the range of VG is not +/- 1 V for  3,3V double supply but is about +/- 0,6 V.
According with VG = +/- 0,6V, how the EQUATION 3 changes?

thanks,
G.P.

  • Hello G.P.

    If you compare charts 34 and 43 you can see that from +-5V to +-2.5V the maximum available gain went from 10 V/V to 9V/V.  the gain range stays the same.  So, for +-3.3V the maxiumum gain would be reduced from 10V/V, but more than 9V/V. 

     If you look at Table 1 you can see that due to headroom limitations the Vg limits are 0.66V. 

    It looks to me like Equation 3 would be similar to this for 3.3V supplies:

    Av = RF/RG * 2.5 * [(VG+0.66)/2]   for -0.66<VG<+0.66

    With this equation and Rf = 1k and Rg=172 the gain would range from 9.59V/V to 0V/V over a gain control range of +0.66V to -0.66V. 

    I think to know more accurately than this would require running tests on an actual circuit. 

    Best Regards,

    Loren

  • Thanks a lot! For my availability of components, I used Rf=1300 and Rg=220 and now my signal conditioning circuit works very well.

    Cordially,

    G.P.