ECE3050 Homework Set 5
1. For K=1.78 mA/V2,VTO =1.5V,V+=18V,R1= 110 kΩ,R2=68kΩ,RD=0,and
RS=1kΩ, write the bias equation, solve for ID, and verify that the MOSFET is biased in the
saturation region, i.e. its active mode. [ID=3.897 mA,VDS =14.10 V,VGS −VTO =1.480 V ]
2. Add a resistor R3from gate to source for the circuit in problem 1. (a) Show that
VGG =V+R2k(R3+RS)
R1+R2k(R3+RS)+IS
RS
RS+R3+R1kR2
×R1kR2
RGG =R1kR2k(R3+RS)
VSS =V+
R1+R2k(R3+RS)×R2
R2+R3+RS
×RS
RSS =(R1kR2k+R3)kRS
(b) For R3=20kΩ, write the bias equation, solve for ID, and verify that the MOSFET is
biased in the saturation region. [ID=0.492 mA,VDS =17.41 V,VGS −VTO =0.526 V]
3. Add a resistor R4from drain to source for the circuit in problem 1. Show that
VSS =V+RS
RD+R4+RS
−ID
RD
RD+R4+RS
RS
RSS =RSk(R4+RD)
VDD =V+R4+RS
RD+R4+RS
+IS
RS
RD+R4+RS
RD
RDD =RDk(R4+RS)
1