Using transistors as signal rectifiers

Thread Starter

studiot

Joined Nov 9, 2007
4,998
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.
 

beenthere

Joined Apr 20, 2004
15,819
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.
 

bloguetronica

Joined Apr 27, 2007
1,371
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.
I guess the advantage of the BC junction is its small size, which allows faster current changes.
 

scubasteve_911

Joined Dec 27, 2007
1,203
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..

Steve
 

Ron H

Joined Apr 14, 2005
7,014
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.
What is your signal frequency and amplitude?
 

Thread Starter

studiot

Joined Nov 9, 2007
4,998
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.
 

Attachments

Top