California State University, Northridge
DEPARTMENT OF ELECTRICAL AND COMPUTER ENGINEERING
ECE340 – ELECTRONICS I
FALL 2009
HOMEWORK ASSIGNMENT #5
Solutions
Problem One
a) Find the DC parameters ID and VDS.
b) Calculate the voltage gain of the amplifier.
c) Find the input and output resistances of the amplifier.
Problem Two
a) Find the value of VDS of the amplifier.
b) Calculate the total voltage gain of the amplifier.
c) Find the input and output resistances of the amplifier.
Problem Three
Design a MOSFET amplifier to the following specifications.
Voltage Gain: ≥ 40
Input Resistance: ≥ 250kΩ
Output Resistance: ≤5kΩ
Use the following transistor parameters:
The Common Source amplifier has high voltage gain, high input resistance, and high output resistance. The Common Gate amplifier has high voltage gain, low input resistance, and high output resistance. The Common Drain amplifier has low voltage gain (< 1), high input resistance, and low output resistance. Therefore the Common Source amplifier is the best candidate circuit structure to meet the above specifications.
Input Resistance:
Output Resistance:
Voltage gain:
Bias Check:
This is just one set of parameter values that meet the design specifications. Other approaches work just as well. The items to pay special attention to are:
a) At least 1 volt difference between VD and VGG.
b) Selection of VGS voltage approximately midway between zero and 5 volts.
c) Selection of VGG and VDD according to resistor divider ratio.
d) Selection of R1 and R2 according to input resistance specification.
e) Selection of RD according to gain and/or output resistance specifications.
Final Circuit:
Problem Four
a) Find the value of VSD of the amplifier.
b) Calculate the total voltage gain of the amplifier.
c) Find the input resistance of the amplifier.
d) Find the output resistance of the amplifier.
Problem Five
a) Calculate the total voltage gain of the amplifier.
b) Find the input resistance of the amplifier.
c) Find the output resistance of the amplifier.