bipolar transistors

[Kevin Weddle]

MOSFETS and biploar transistors are very similar. MOSFETS don't have base current, which seems easier for design purposes. And their transfer curve is much better.

Why are MOSFETS only used in output power stages?

 

[Hero999]

BJTs have the following advantages over MOSFETS:

• The input is not capacitive.
  
• They're cheaper.
  
• The turn-on voltage is only 0.6V which means they can be used in very low voltage circuits <1V.
  
• They have a higher gain.
  
• BJTs are more resistant to ESD than MOSFETs.
  

I've answered your question under the condition that you don't fill the rest of the thread with random comments which are often incorrect. If you want to ask more questions then you're free to do so but please make it clear what you're asking.

 

[Kevin Weddle]

Turn-on voltage .6V. All designs are depenedent on voltage and curent. Voltage is a real consideration. But you can use any value of voltage for a circuit.

 

[Hero999]

No you can't use any voltage you like.

What if you're restricted to using a single AA cell? Then you're limited to 1.5V.

 

[Kevin Weddle]

Most designs can't account for the linearity difference between bipolar transistors and MOSFETS. But very large designs suffer from linearity problems, component manufacturing, design etc.