1. E-MOSFET The E-MOSFET or enhancement MOSFET can operate in only the enhancement mode. With a positive voltage above a threshold value on the gate, an induced channel of thin layer of –ve charges is created. The conductivity of channel is enhanced by increase VGS and thus pulling more electrons into channel area.

2. E-MOSFET Characteristics and Parameters The E-MOSFET for all practical purposes does not conduct until V GS reaches the threshold voltage (V GS(th) ). [I D =0 when V GS <V GS(th) ] I D when conducting can be determined by the formulas below. K = I D(on) /(V GS - V GS(th) ) 2 I D = K (V GS - V GS(th)) 2

3. MOSFET Biasing- voltage divider bias For E-MOSFETs zero biasing cannot be used. Voltage-divider bias must be used to set the V GS greater than the threshold voltage (V GS(th) ). I D can be determined as follows. To determine V GS, normal voltage divider methods can be used. The following formula can be applied. V GS = (R 2 / (R 1 +R 2 ))V DD V DS = V DD - I D R D K = I D(on)/ (V GS - V GS(th) ) 2 I D = K(V GS -V GS(th) ) 2 V DS can be determined by application of Ohm’s law and Kirchhoff’s voltage law to the drain circuit.

4. Example 7-16 Determine V GS and V DS for E-MOSFET circuit below. Assume MOSFET has minimum values of I D(on) =200mA at V GS =4V and V GS(th) =2V.

5. MOSFET Biasing- drain feedback bias With drain-feedback bias there is no voltage drop across R G making V GS = V DS. With V GS given determining I D can be accomplished by the formula below. I D = (V DD – V DS )/R D