辅导EEET1415-Assignment 1讲解 Circuits and Simulations

EEET1415 and EEET 1467 – Circuits and Simulations
Assignment 1
Date: 08-04-2020

Circuits and Simulations – Assignment 1

Task 1 – Resistor biased differential amplifier (20 marks)

1) Simulate the differential amplifier in Figure 1 and find the following DC parameters
(5 marks)

Figure 1 – Differential amplifier using resistor biasing

Table 1 - DC biasing parameters
VG1 VG2 VSS VD1 VD2 ID1 ID2 ISS
Measured
Parameters


2) Calculate (Attaching the worked solution as an appendix) the small signal common
mode and differential gain of the amplifier in Figure 1. (9 marks)
Hint: use the previous question’s DC parameters to find the small signal parameters
ISS
Vout
EEET1415 and EEET 1467 – Circuits and Simulations
Assignment 1
Date: 08-04-2020
2


3) Simulate a differential mode small signal input and find the single ended differential
gain, (2.5 marks)

4) Simulate a common mode small signal input and find the common gain, (2.5
marks)

5) From questions 3 and 4, calculated the ⌉ for the resistor biased differential
amplifier (1 mark)

EEET1415 and EEET 1467 – Circuits and Simulations
Assignment 1
Date: 08-04-2020
3

Task 2 – Improving the differential amplifier (20 marks)

1) Replace R1 with a simple MOSFET current mirror. Find the correct resistance value
for RCurrentMirror to achieve the current shown in Figure 2. (10 marks)


Figure 2 - Differential amplifier with current mirror

2) Find the simulated differential mode gain (( )) and common mode
gain ( ) for the circuit in Figure 2. (8 marks)

3) Use ( ) and ( ) calculate the ⌉ for
differential amplifier with a current mirror. (2 marks)
EEET1415 and EEET 1467 – Circuits and Simulations
Assignment 1
Date: 08-04-2020
4

Task 3 – Replacing R1 and R2 with an active load (20 marks)

1) Replace R3 and R2 with a P-MOS complimentary active load, shown in Figure 3.

Figure 3 - Differential amplifier with current mirror and active load

2) Find the simulated differential mode gain (( )) and common mode gain
( ) for the circuit in Figure 3. (5 marks)

3) Use ( ) and ( ) calculate the ⌉ for differential
amplifier with a current mirror. (5 marks)

4) Draw a table comparing the , , ⌉, number of components used in
the circuits of figures 1 – 3. Comment on differences and why each task improves on
the previous circuit. (10 marks)