Voltage follower output voltage

Discussion in 'General Electronics Chat' started by Oussama Zaidi, May 27, 2016.

  1. Oussama Zaidi

    Thread Starter Member

    Mar 1, 2016
    I use TLE2024 in the circuit in the picture below as a voltage follower, I choose it for its low offset voltage (850uV max), the problem is when I simulate it in proteus with an input very close to zero the output is much bigger when Vee is connected to GND, only when Vee= -Vdd I have an output close to 0 too, I can't figure the reason, does anyone has an idea? follower.PNG follower_1.PNG
    Last edited: May 27, 2016
  2. Kjeldgaard


    Apr 7, 2016
    The selected operational amplifier has the correct data for common mode voltages at the input (includes the negative rail).
    But the output can, according to the data sheet, with 10K Ohm load and 5V supply, just go down to approximately 0.8V.
    So there must be found a type of amplifier with rail to rail output.
  3. crutschow


    Mar 14, 2008
    Try putting one or two diodes in series with the feedback loop (anodes to output) and take the output from the diode cathode (connected to the minus op amp input) with a 10kΩ resistor to ground at the minus input.
    That should add enough offset to give zero volts across the 10kΩ with 0V in.

    Here's the circuit:
    Oussama Zaidi and AnalogKid like this.
  4. JMac3108

    Active Member

    Aug 16, 2010
    Like Kjeldgaard said, you need a rail-to-rail type op-amp. The TLE20204 will only go to within about 0.8V of its rails (positive and negative supplies). Look around on the TI site for op-amps designated as "rail to rail".

    Cool circuit ... never thought of that!