High-Frequency Electronics
Prof. Dr.-Ing. Andreas Thiede
Analog CMOS Integrated Circuits
Exercise 4: Common-Drain, Common-Gate, and Cascode Stage
1.
Find the small signal representation based on Thevenin equivalent (voltage source type
two pole equivalent) of the internal source follower, i.e. an ideal source follower without
body effect and channel length modulation.
Next complete this equivalent with external components to include body effect and
channel length modulation. Finally add a load resistor RS and compare the resulting gain
with the gain derived in the lecture !
What gain will be obtained, if the load resistor RS is replaced by a diode-connected pchannel MOSFET ?
2.
Determine the voltage gain of the common-gate stage loaded by an ideal current source.
Argue why the gain does not depend on the source resistance RS anymore !
What will be the transimpedance vout / iin of this stage if the input is driven by a current
source with the internal resistance RS ?
3.
Determine the equivalent transconductance Gm of the depicted
VDD
cascode stage !
RD
Set up the Norton equivalent including the output resistance
rout derived in the lecture and calculate the voltage gain of the
VOUT
Vb
M2
VIN
M1
amplifier !