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