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Unformatted text preview: Several important point should be noted: 1) No current flows into the gate, i G = 0 (note the insulator between gate and the body). 2) When FET is in cut-off, i D = 0. However, i D = 0, does not mean that FET is in cut-off. FET is in cut-off only when no channel exists ( v GS < V t ) and i D = 0 for any applied v DS . However, FET can be in triode region, i.e., a channel is formed, but i D = 0 because v DS = 0. 3) The FET saturation region is called saturation because i D is saturated in this region and does not increase further. Some of the modern books call this active region as it is equivalent to active-linear region of a BJT (and not the BJT saturation). 4) The i D v DS characteristic curves of a FET look similar to i C v CE curves of a BJT. In fact, as there is a unique relationship between i B and v BE , the i C v CE curves of a BJT can be labeled with different values of v BE instead of i B , making the characteristic curves of the two devices even more similar: In FET...
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- Spring '08