EFFECT OF RECOMBINATION !!!!!

[electronics_kumar]

since MOSFET(UNIPOLAR) says big no recombination process wheras BJT(BIPOLAR) allows recombination to takes place......so what MOSFET achieves by this or else what else BJT attains by having this recombination process

 

[laktronics]

Hi,
MOSFET has high input impedance and naturally suitable for voltage amplification. BJT had 'early bird advatage' of having born earlier in the technology chain, low input impedence due to recombination, basically a current amplifier, is cheaper, may be due to technology or large volume production.
Regards,
Laktronics

 

[electronics_kumar]

Hi,
MOSFET has high input impedance and naturally suitable for voltage amplification. BJT had 'early bird advatage' of having born earlier in the technology chain, low input impedence due to recombination, basically a current amplifier, is cheaper, may be due to technology or large volume production.
Regards,
Laktronics

i could not sense any answer from your post.....expecting replies for my query...

 

[forkschgrad]

i think what laktronics wants to say is recombination affects the switching capacity of BJT and MOS.

 

[laktronics]

Hi,
What I meant is that the base current in the transistor is due to the recombination process. By applying a small base current Ib, an input signal produces βIb at the collector of a transistor, that is why the transistor is called a current amplifier. But the input source gets loaded to the extent of Ib which effectively reduces the input impedance of the transistor.

If you consider either MOSFET or a FET, there is no recombination and they work as a voltage controlled devices, just like vacuum tubes. So, the input signal does not have to provide current as in the case of transistor, in other words, due to the absence of recombination, FET devices offer high input impedance.

Apart from speed and cost advantages, transistor devices are still around because they were developed much earlier than FETs and continue to be patronised by users inspite of low input impedance. There could be other reasons also for transistors being used even now.
Regards,
Laktronics