ASSIGNMENT #1 JUNE 2018 201CDE ANALOG AND DIGITAL ELECTRONICS

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ASSIGNMENT #1 JUNE 2018 201CDE ANALOG AND DIGITAL ELECTRONICS

(ADE)

1. The objective of simulation is to verify and optimize the design.

Simulation can idealize a circuit. The objective of measurement is to experimentally confirm the specifications. Measurements must consider all non-idealities.

a. Describe completely the definition of the Common Mode Rejection Ratio (CMRR) of an operational amplifier. Recommend a circuit to measure the CMRR. Use MULTISIM to conduct the measurements of CMRR. Provide the plot of the CMRR (in dB) versus Frequency (Hz) to prove the efficacy of the OPAMP.

15 Marks

b. What do you understand by the term “slew rate” of an operational amplifier? Recommend a circuit to measure this parameter and provide complete measurement of this parameter using the MULTISIM environment.

15 Marks

2. Design an operational amplifier circuit that performs the mathematical operation of integration with respect to time; that is, its output voltage is proportional to the input voltage integrated over time..

5 Marks

a. Explain fully the operation of the circuit and derive its input/output characteristic equation.

10 Marks

b. Using MULTISIM show the performance of the circuit when the input was impressed with the following waveforms.

i. Square Wave ii. Triangular Wave

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iii. Sine Wave 10 Marks

c. Show that if the input is a sine wave of varying

frequency the OPAMP integrator performs like an active low-pass filter.

5 Marks

3. An oscillator is the basic element of all AC signal sources and

generates sinusoidal signals of known frequency and amplitude. It is one of the basic and useful instruments used in electrical and electronic measurement. Oscillators are used in many electronics circuits and systems providing the central clock signal that controls the sequential operation of the entire system.

a. Describe the operation of an OPAMP-based oscillator

using the concept of a basic oscillator feedback circuit. Your description must include all pertinent equations relating the overall closed loop gain and the open-loop and feedback gain

10 Marks b. Figure 1 shows the complete schematic diagram of a

variable frequency COLPITTS Oscillator. Use the MULTISIM platform to simulate the operation of this oscillator as you vary the values of the inductor, 𝐿, from 1𝜇𝐻 to 62𝑚𝐻. What is the gain of the oscillator?

3 Marks

i. Tabulate the output frequencies versus the various inductor values.

7 Marks

ii. Show the output waveforms as displayed on the oscilloscope for ten selected frequencies.

10 Marks

iii. Show the output waveforms as displayed on the spectrum analyzer of the output amplitude versus frequency.

10 Marks

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Figure 1: Complete schematic diagram of a COLPITTS Oscillator