Using transistors as signal rectifiers

Discussion in 'General Electronics Chat' started by studiot, Jan 16, 2008.

  1. studiot

    Thread Starter AAC Fanatic!

    Nov 9, 2007
    Any experience of using transistors as signal rectifiers welcome.
    A few years back I did see a cross coupled bridge of 4 transistors running at 50 times the Ft of the transistors themselves but these were complementary pairs and I have no very high frequency PNP transistors.
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    I have used a transistor's BC junction as a diode in an emergency situation. There are so many signal and rectifier diode types available that there does not seem to be much utility in using transistors for the purpose.
  3. cumesoftware

    Senior Member

    Apr 27, 2007
    I guess the advantage of the BC junction is its small size, which allows faster current changes.
  4. scubasteve_911

    Senior Member

    Dec 27, 2007
    I remember seeing a circuit in an old IEEE paper that used matched pairs that seemed to be slightly biased used to rectify signals with precision and speed proportional to the transition frequency.

    I took a look, but I couldn't seem to find it..

  5. Ron H

    AAC Fanatic!

    Apr 14, 2005
    What is your signal frequency and amplitude?
  6. studiot

    Thread Starter AAC Fanatic!

    Nov 9, 2007
    I was experimenting with building an electromagentic wave detector and trying to see how high a frequency I could get. Sensitivity is also an issue as I can't amplify the pickup before rectification.

    I was looking at the attached circuit where the originator used germanium transistors with an Ft of 1 - a few Mhz and claims to have achieved a sensitivity of 30millivolts at 30Mhz.