LM358

• https://en.wikipedia.org/wiki/Operational_amplifier
• http://www.ti.com/lit/ds/symlink/lm358-n.pdf
• http://pdf1.alldatasheet.com/datasheet-pdf/view/8674/NSC/LM358M.html

Phase shifter circuit

(From Richard Karlquist)

Here is a well known op-amp phase shifter. I am surprised no one has posted it yet, so I guess I will have to. The circuit will have 90 degrees phase shift at:

         FREQ = 1/(2*PI*R3*C)

At low frequencies it has 0 degrees of phase shift and at high frequencies it has 180 degrees of phase shift. By making R3 a pot, you can vary the phase at a given frequency from nearly 0 to nearly 180 degrees. Since you want to work at 1 MHz., you will need to use a high frequency op amp, like the Burr-Brown OPA620.

      R1=R2                   |---\/\/\/\/\\/\--|
                              |       R2        |
                              |                 |
                 R1           |     |\          |
                              | INV | \         |
INPUT --------\/\/\/\/\/\/----------|  \        |
          |                         |   \       |
          |                         |    \-------- OUTPUT
          |       R3                |    /
          |                 NON-INV |   /
          |---\/\/\/\/\/\/----------|  /
                              |     | /
                              |     |/
                              |
                              |
                           -------  C
                           -------
                              |
                              |
                              |
                              |
                           GROUND