# ASSIGNMENT #1 FEBRUARY 2021 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

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, ????,

from 1???????? to 62????????. 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)

Figure 1: Complete schematic diagram of a COLPITTS Oscillator (Diagram in PDF)