The backwards transistor

[Kevin Weddle]

I have an idea to develop a backwards transistor. I had this idea from the limitations I was getting. I wanted to operate the collector of a common base as an emitter. The reason is for the high impedance aspect of the collector as seen by the rest of the circuit. If I used an emitter, the impedance is the base resistor divided by beta. We all know that the biased base resistors must not be too high else you won't have enough current difference that is applied to the base. We all know that the impedance of this backwards transistor will be the change in voltage divided by the change in current. If I make the change in current low I have a low change in current on the output. This makes the input impedance high and the most notable feature is that I can get voltage gain. This sounds like a common emitter function, but consider that this function will produce inversion. With a backwards transitor, though you can have voltage gain, a high input impedance, and no inversion. I don't want inversion because I want a fairly large signal and the beta would change too much. I need an increase to occur on both sides of the transistor.

 

[Yevgenip]

I think it is called a MOSFET but I'm not sure.

 

[Kevin Weddle]

Doesn't a MOSFET also have the same problem when you apply a signal to the source. The input impedance is too low. It is only 1/gm.

 

[surajbarkale]

The common base configuration works because collector can provide same current as emitter without caring for the load voltage. Indeed collector acts as a constant current source. You can not operate emitter this way so at the max you will get an attenuator.
In fact you can view a voltage regulator as the backwards transistor. And i don't think it offers any gain ;D

 

[MP1]

Kevin, do you mean a transistor that is flat on the wrong side? This would surely be put in the board backwards.

(I am only joking with you) ;D

MP

 

[Yevgenip]

Yeah, or a transistor with his pins misplaced, so you need to guess which pin is which! Won't that be fun? ;D