Henry said:
Do anyone know the simplest way to convert range (-1.6V to 3.4V) to
the range 0-3.3V by using Op-Amp?
Why use an opamp? You don't need any gain, so a simple passive summing
network will do fine. Assuming zero source impedance and infinite load
impedance, this should work:
___ ___
IN --|___|-o-|___|-- +3.106V
|
1.7k | 3.3k
|
|
OUT
The 1.7k and 3.3k resistors achieve the scaling from 5V to 3.3V range. The
3.106V value comes from fixing Vi at -1.6V, Vo at 0V, and solving for the
current through the two resistors, Vi / 1.7k = - Vx / 3.3k.
Of course, if you don't have a handy 3.106V supply around, you could be a
little more clever - note that the parallel combination of the 15.94k
resistor and the 4.16k resistor is still equal to 3.3k:
___ ___
IN --|___|-o-|___|-- +15V
| 15.94k
1.7k |
| ___
o-|___|-- GND
| 4.16k
|
OUT
And if you have nonzero input impedance, you could correct for it by
changing the input resistor, or just by scaling all the resistors to be in
some reasonable range.
-walter
