Analog Circuits (EE3002/EE5310) : Problem Set 5
shanthi@ee.iitm.ac.in
Problem 1 Problem 2
5V
5V
(10/1) (40/1)
(10/1) (40/1)
M1 1.5M M2
M1 M2 (170/1)
2M vout
M3
M4 2.5M M3
vi vi
(10/1) (40/1)
vout
10 µΑ
10 µΑ
1M
3M RE=10 K
|VTp|=0.8V, µpCox=50µΑ/V2
VTn=0.7V, µnCox=200µΑ/V2
|VTp|=0.8V, µpCox=50µΑ/V2 Figure 2: Circuit for problem 2.
Figure 1: Circuit for problem 1. • Determine the operating points of all the devices in the circuit.
For this part, assume λ = 0 for all devices.
In the amplifier of Fig. 1, • All transistors have finite output impedance, such that for any
transistor, gm ro = 100. Draw the small signal equivalent
• Determine the operating points of all the devices in the circuit. circuit of the amplifier. Determine the small signal gain from
For this part, assume λ = 0 for all devices. vi to vout and the input and output resistances of the amplifier.
To find input resistance, assume that the load is infinity. To
• All transistors have finite output impedance, such that for any find the output resistance, assume that the source driving the
transistor, gm ro = 100. Draw the small signal equivalent amplifier has zero internal resistance.
circuit of the amplifier. Determine the small signal gain from • Determine the amplitude of the largest sinusoid that can be
vi to vout and the input and output resistances of the amplifier. applied at the input, so that the output is also a sinusoid, de-
To find input resistance, assume that the load is infinity. To void of clipping effects. As usual, assume that the coupling
find the output resistance, assume that the source driving the capacitors are infinite.
amplifier has zero internal resistance.
• Determine the amplitude of the largest sinusoid that can be Problem 3
applied at the input, so that the output is also a sinusoid, de-
void of clipping effects. As usual, assume that the coupling • Determine the operating points of all the devices in the circuit.
capacitors are infinite. For this part, assume λ = 0 for all devices.
1
5V • Determine the operating points of all the devices in the circuit.
Assume λ = 0 for all devices. The answers should be in terms
(10/1) (40/1) of |VT P |, VT N , µn Cox , µp Cox , R, Vdd &(W/L).
M1 1.5M M2
20K vi • What is the transconductance of M1 ? How does it depend on
the device thresholds, µn Cox and µp Cox ? What do you think
M3 the practical utility of this circuit is ?
(40/1)
• Determine the minimum Vdd required to ensure that all de-
vout vices are in saturation.
10 µΑ
1M 40K
Problem 5
|VTp|=0.8V, µpCox=50µΑ/V2 5V
(10/1) (100/1)
Figure 3: Circuit for problem 3.
M1 M2
(40/1)
• All transistors have finite output impedance, such that for any vi Rout
transistor, gm ro = 100. Draw the small signal equivalent 20K
Rin vout
circuit of the amplifier. Determine the small signal gain from
vi to vout . M3
10 µΑ (100/1) 40K
• Determine the amplitude of the largest sinusoid that can be
applied at the input, so that the output is also a sinusoid, de- (10/1) (10/1)
void of clipping effects. As usual, assume that the coupling
capacitors are infinite.
|VTp|=0.8V, µpCox=50µΑ/V2
VTn=0.7V, µnCox=200µΑ/V2
Problem 4
Figure 5: Circuit for problem 5.
In the circuit of Fig. 4, assume that all devices operate in saturation.
The circuit of Fig. 5 shows an amplifier.
Vdd
• Determine the operating points of all the devices in the circuit.
R For this part, assume λ = 0 for all devices.
M2 M1 • All transistors have finite output impedance, such that for any
(4W/L) (W/L) transistor, gm ro = 100. Draw the small signal equivalent
circuit of the amplifier. Determine the input resistance of the
amplifier. What kind of controlled source is this ? Determine
the relevant ”transfer” parameter of the source.
(W/L) (W/L)
• Determine the amplitude of the largest sinusoid current at the
input, so that the output is also a sinusoid, devoid of clipping
effects. As usual, assume that the coupling capacitors are in-
finite.
Figure 4: Circuit for problem 4.
