Absolute Value Generator vs. Full-Wave Rectifier

Discussion in 'General Electronics Chat' started by BobbyTheD, Apr 22, 2016.

  1. BobbyTheD

    Thread Starter New Member

    Mar 10, 2016
    12
    0
    Hi AAC -

    I'm looking at circuit 16 in Texas Instruments AN-20, http://www.ti.com/lit/an/snoa621c/snoa621c.pdf.

    The circuit uses two large capacitors at the input and, in the notes, it states that this is the difference between the circuit functioning as an "Absolute Value Generator" and a "Full-Wave Rectifier."

    Could someone explain the difference to me?

    Also, the offsets seem very large on the non-inverting inputs. I'm not sure if anyone has experience with the LM107 in contrast with the TL074 - but is it possible that modern op-amps don't require that kind of compensation?

    Thanks.
     
  2. #12

    Expert

    Nov 30, 2010
    16,313
    6,817
    Fig. 16. Photovoltaic Cell Amplifier
    This isn't working. Please clarify.
    Yes. I was there for the LM101. Offset voltage has improved quite a bit since then.
     
  3. BobbyTheD

    Thread Starter New Member

    Mar 10, 2016
    12
    0
    Sorry, it's circuit 16 - in the table of contents... it's figure 25.
     
  4. #12

    Expert

    Nov 30, 2010
    16,313
    6,817
    If you short out C1 then this full wave rectifier will respond to any DC level at the input. With the capacitor, it's a full wave rectifier of the AC signal. Without the capacitor it's still a full wave rectifier, but it will include any DC component in its activities.
     
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