transistor as a diode

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isanjeev

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can shorting of the emitter and base of a transistor be used as a diode?
emitter is heavily doped as compared 2 base......this will lead to the depletion layer extending more into the base(right?)
will this leave enough of base for proper transistor action?
And what are other ways to make a transistor act as a diode?
 

To use a transistor as a diode you would normally connect the base to the collector.

Keith.
 

To use a transistor as a diode you would normally connect the base to the collector.
Click to expand...
To get more than 5 or 7 V reverse voltage, you would rather utilize the BC junction. The emitter must no necessarily be shorted to the base.
 

Is shorting of base and collector the only way for a transistor to act as a diode?.......aren't there any other ways?
keeping the emitter open, a small leakage current ( in the scale of µA) would flow.for practical purposes can this current be neglected ? considering that we want the transistor to act as a diode(can the same be considered with the the collector open in the transistor with the emitter and the base connected)
 
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You have not specified the use for your 'diode'. A (bipolar) transistor has two PN junctions, both can be used as individual diodes, C-B or B-E but have slightly different characteristics.
If you want to utilize the full current capability of the transistor, for example if you are using it as a power rectifier, join the B & C together so it conducts and clamps Vf at Vbe.

Brian.
 


what are the various ways to make a (bipolar)transistor act as a/any diode (any application)
 

Transistors are designed to be switches or amplifiers, not diodes so none of the PN junctions are optimized for use as a diode.

Please bear in mind that transistors range from microwave amplifiers to massive current switches and even to multi-kilovolt switches, trying to characterize them in terms of PN parameters simply isn't possible.

Brian.
 

Can we do this by shorting emitter to collector? In that case Base will be p type and other shorted end will be n type in case of npn transistor. Is it possible?
 

You are resurecting an old thread but the answer is yes but you only get a low PIV, low-current, high capacitance diode, shorting base to collector and using the emitter as the other electrode will work better in almost all cases.

Brian.
 

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