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CORK INSTITUTE OF TECHNOLOGY
INSTITIÚID TEICNEOLAÍOCHTA CHORCAÍ
Semester 2 Examinations 2010
Module Title: Electronic Engineering
Module Code: ELTR
School: School of Electrical & Electronic Engineering
Programme Title: Bachelor of Engineering in Electronic Engineering – Year 3
Programme Code: EELXE_7_Y
External Examiner(s): Dr. A. Donnellan & Dr. Paula O’Sullivan
Internal Examiner(s): Dr. P. O’Connor
Instructions: Answer QUESTION 1 (worth 40 marks) and TWO other questions (worth 30 marks each)
Duration: 2 HOURS
Sitting: Autumn 2010
Requirements for this examination: Graph paper, Log Tables
Note to Candidates: Please check the Programme Title and the Module Title to ensure that you have received the correct examination paper. If in doubt please contact an Invigilator.
- (i) Assuming an ideal Op-Amp, and R 1 = 100kΩ, Rf = 500kΩ and Vin = 2V (standard notation), calculate the output voltage (Vout) for (a) Inverting amplifier (b) Non-inverting amplifier. (5 marks)
(ii) For the summing amplifier shown in Fig.1(ii), calculate the output voltage for the following sets of input voltages and resistors. (use R = 1MΩ in all cases). (a) V 1 = 1V, V 2 = 2V, V 3 = 3V, R 1 = 500kΩ, R 2 = 1MΩ, R 3 = 1MΩ (b) V 1 = -2V, V 2 = 3V, V 3 = 1V, R 1 = 200kΩ, R 2 = 500kΩ, R 3 = 1MΩ
(5 marks)
(iii) Calculate the total offset voltage for the circuit shown in Fig.1(iii) for an Op-Amp with specified values of input offset voltage, VIO = 4mV and input offset current IIO = 150nA. (5 marks)
(iv) An inverting amplifier has a gain of 24. The Op-Amp has a slew rate of 0.5 V/μs and an input signal voltage of 0.02 V. Determine the maximum frequency that may be used before distortion due to slew rate limiting affects on the signal. (5 marks)
(v) Write a technical note on the AC-Performance of Op-Amps. Your explanation should include the UGB, (^) fc ( OL ), (^) fc ( CL ), and a frequency response curve to demonstrate your understanding. (5 marks)
(vi) Design a basic R-C High-Pass filter with a cutoff frequency of 10kHz. (State any assumptions). Your answer should include (a) Calculations for R & C (b) Circuit diagram (c) Bode plot (5 marks)
(vii) A boost converter has an input of 10V and an output of 20W at 15V. The minimum inductor current must be no less than 50% of the average. The out voltage ripple must be less than 1%. The switching frequency is 30kHz. Find the duty-cycle, the minimum inductor value and the minimum capacitor value. (5 marks)
(viii) Calculate the output voltage for the circuit shown in Fig.1(viii). (5 marks)
- (a) Draw a circuit for a basic Op-Amp series regulator and explain its operation. A series linear regulator with constant current limiting has the following parameters (normal notation): Vref = 1.25V, R 2 = 60k𝛺, R 3 = 20k𝛺. The limiting resistor = 0.45𝛺. Find the output voltage and the maximum output current.
(10 marks)
(b) Explain, using a circuit diagram, what a Boost Converter is? A boost converter has the following parameters (normal notation): Vs = 20V, D = 0.6, L = 65μH, C = 200μF, f = 40kHz and R = 12.5𝛺. Find (i) The output voltage (ii) The maximum and minimum inductor currents (iii) The output % ripple.
(12 marks)
(d) Write a short technical note on Sensors. Include the following in your discussion:- (i) Sensor types (ii) Reading sensor inputs (iii) Applications (8 marks)
Fig.1(ii)
Fig.1(iii)
