In the image(http://www.allaboutcircuits.com/vol_3/chpt_4/4.html), the result of SPICE simulation for active mode operation of BJT is shown.
The current source is set at a constant value of 20uA and the collector bias voltage is varied from 0 to 2V.
If you see the description of the image, it's mentioned that:
"A Sweeping collector voltage 0 to 2 V with base current constant at 20 µA yields constant 2 mA collector current in the saturation region"
Constant 2 mA collector current in the 'Saturation Region'? As I have understood, the saturation region is the part that lies to the left of active region(where Vce is almost zero) From what is shown in the image is it not that the 2 mA collector current in Active Region?
If the voltage is increased above 2V, there would be no change in the collector current as it's limited by the base current. The maximum current that we have as output is 2mA. How do you say that the transistor is now in Saturation mode?
Please explain me why the saturation region is indicated to the left of active region? From the characteristic curves, it seems that the region that is marked as 'active', is actually the Saturation because there is maximum collector current there.
Best Answer
You have understood this correctly and it appears the author of the document you linked is wrong - for a MOSFET they have perfectly described the saturation region but, this is a BJT circuit and the saturation region is the left hand side. Here's the drawing they talk about: -
Saturation is when the current and voltage rise almost linearly together for a fixed base current.