Vout A1 R1 R2 Figure Q4b: The control and amplifier circuitry in the Sensor head a) Using the above information and assuming a reference current (Idc)=250uA, draw a table of the resistance of a single PT-1000 sensor for the temperatures 0, 50, 100, 250, 300 °C and the de input signal this would generate at the input to amplifier A1 b) Including any noise produced by Idc (but excluding shot noise), re-draw the circuit diagram showing all sources of noise. c) Hence derive an expression for the voltage noise spectral density present at the output (Vout) of the amplifier at a room temperature of 25 °C. Clearly identify each source of noise in your calculations and state any assumptions you make. d) The operational amplifier 'A1' is one of the three shown in Table Q4b: OpAmp Vn (nV /VHz) in (fA/VHz) Amplifier A Amplifier B Amplifier C 1.3 1500 12 25 6.8 1200 Table Q4b If RI = 9002 and R2 = 1002 and without making detailed calculations, draw a table comparing the performance of each amplifier and identify which would to be most suitable for this application. Explain your reasoning using a suitable diagram. e) Using your amplifier choice from part (d), and assuming the temperature of the sensor and the circuit = 25 °C, R1 = 9002, R2 = 1002, and Idc = 250uA, what level of noise from Idc could be tolerated that would increase the overall noise appearing at the output (Vout) by +3dB? PHYSICAL CONSTANTS Absolute zero should be assumed as -273.15 °C; Boltzmann Constant = 1.38 x 10-23 J.K-