This document is a project report on designing an audio amplifier. It discusses the objective of understanding how amplifiers work and their purpose of increasing low power audio signals to suitable levels for speakers. It describes what an amplifier is and why they are needed to boost signal power using an external energy source. It also outlines best practices for laying out amplifier circuits, including using a ground plane, proper decoupling and EMC component placement to minimize interference and optimize performance.

1. Audio Amplifier
PROJECT REPORT
By : Arbaz Khan
BEES/S14/0234
Basic Elec- LAB

2. Audio Amplifier:
An audio amplifier is an electronic amplifier that amplifies
low-power audio signals (signals composed primarily of
frequencies between 20 - 20 000 Hz, the human range of
hearing) to a level suitable for driving loudspeakers and is the
final stage in a typical audio playback chain.

3. Objective:
 The main objective of this is to understand the working
of amplifiers.
Purpose:
 The purpose of this project is to understand the need
and working of amplifiers.
Description:
 Before we go into the depth of our project, we first
need to understand what is an amplifier and why do
we need it?

4.  An amplifier is a device for increasing the power
of a signal by use of an external energy source. In
an electronic amplifier, the input "signal" is
usually a voltage or a current. Other types exist; a
fluidic amplifier increases the power of signals
represented as flow of as or liquid, for example.
Amplifiers may be classified in a variety of ways
depending on their application, the frequency
range they cover, or the active devices used.
Ideally an amplifier increases the power of a
signal without otherwise altering it; practical
amplifiers have finite distortion and noise which
they invariably add to the signal.
 The quality of an amplifier can be characterized
by a number of specifications, listed below.

5. 1. The gain of an amplifier is the ratio of output to
input power or amplitude, and is usually measured in
decibels. (When measured in decibels it is
logarithmically related to the power ratio: G(dB)=10
log(Pout /(Pin)). RF amplifiers are often specified in
terms of the maximum power gain obtainable, while
the voltage gain of audio amplifiers and
instrumentation amplifiers will be more often Gain
specified (since the amplifier's input impedance will
often be much higher than the source impedance, and
the load impedance higher than the amplifier's output
impedance). For example, an audio amplifier with a
gain given as 20 dB will have a voltage gain of ten (but
a power gain of 100 would only occur in the event the
input and output impedances were identical).

6. Order of Priority
 Ground Plane
 Decoupling Placement and Connection
 EMC Circuit Placement and Connection
 Input and Analog Control Routing

7. Ground Plane (Cont’d)
 Use ground plane to connect all critical
circuits
 This minimizes ground impedance,
especially

8. Ground Plane (Cont’d)
 Place the IC at the center of the ground plane
and ground the PowerPAD
 Ground decoupling caps and EMC
components to the PowerPAD area through
ground plane.
 Place inputs on one side of the circuit and
power and outputs on another to separate the
currents.
 This approach minimizes interference that could
reduce audio quality and makes decoupling
and EMC filters and snubers work best.

9. Poor vs. Proper Decoupling

10. EMC Filtering (cont’d)
 Place EMC snubbers& filters very near the IC.
 Ground through ground plane & connect
outputs to cap pads, directly or through
broad copper, & not to inductors, to minimize
stray inductance
 Place EMC filter caps as close to the IC as
possible on the ground plane layer and
ground them to the IC through the ground
plane

11. EMC Filtering (cont’d)
 This approach minimizes unfiltered loops
and trace lengths as well as stray
inductance.
 This makes EMC components function
best & gives the widest possible filter
bandwidth.

12. Poor vs. Proper Filter Placement

13. Circuit Diagram

14. Thank You
For your attention