You might try an octaver like the POG, HOG, Micro POG, or a Digitech Whammy (or variations thereof). Just about any digital octave unit should get you something close to what you are looking for. Analogue octavers will be more gnarly and have some distortion at various settings. This isn't particularly a bad thing, but it's probably not what you are looking for. If you want something that tracks notes flawlessly, my personal suggestion would be to go with a POG, HOG, or Micro POG as these units will have the best tracking. You can also turn down the original signal, and then play one octave up on your neck with the pedal set to -1oct and it should sound synthy and digitally "fake". If you search around on here, you should be able to find reviews and sound clips for all three of these units.
