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DAC Edited

The document provides an overview of digital-to-analog converters (DACs), including their function, types (binary weighted resistors and R/2R ladder resistors), and performance specifications such as resolution and errors. It also discusses applications of DACs in various devices like CD players and digital oscilloscopes. The document concludes with a comparison of the two types of DACs, highlighting their pros and cons.

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ضياء بن احمد الكباري
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27 views27 pages

DAC Edited

The document provides an overview of digital-to-analog converters (DACs), including their function, types (binary weighted resistors and R/2R ladder resistors), and performance specifications such as resolution and errors. It also discusses applications of DACs in various devices like CD players and digital oscilloscopes. The document concludes with a comparison of the two types of DACs, highlighting their pros and cons.

Uploaded by

ضياء بن احمد الكباري
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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• Outline

❑Introduction
❑Review of Op-Amps
❑Types of digital to analog conversion
❑ Binary weighted resistors
❑ R/2R Ladder resistors
❑Examples
❑Devices
❑Applications
• Introduction

❑ Digital-to-analog converter (DAC, D/A, D2A, or D-


to-A) is a system that converts a digital signal into
an analog signal. An analog-to-digital converter
(ADC) performs the reverse function.
❑ DACs are often used to convert finite-precision
time series data to a continually varying physical
signal.
• Introduction

2 3 4
5
1
Digital Actuator
Transducer ADC DAC
System

Electrical Digital Digital


Analog Inputs Output
Signal Analog
Output
• Introduction
• Review of Op-Amps

❑ Virtual ground concept


and closed-loop voltage
gain development for the
inverting amplifier.
• Review of Op-Amps

❑ Summing Amplifier
• Types of DAC
Binary weighted resistors

❑ A scaling adder as a four


digit DAC
• Types of DAC
Binary weighted resistors

❑ Example:
• Types of DAC
Binary weighted resistors

❑ Solution:
• Types of DAC
Binary weighted resistors

❑ Solution:
• Types of DAC
R/2R Ladder resistors
• Types of DAC
R/2R Ladder resistors

❑ Equivalent Ladder circuit


with D2,D1,D0 grounded
−𝑉𝑟𝑒𝑓 −𝑉𝑟𝑒𝑓
❑ 𝐼3 = =
2𝑅+2𝑅||2𝑅 3𝑅
• Types of DAC
R/2R Ladder resistors

❑ Equivalent Ladder circuit


with D3,D1,D0 grounded
−𝑉𝑟𝑒𝑓 −𝑉𝑟𝑒𝑓
❑ 𝐼2 = =
2𝑅+2𝑅||2𝑅 3𝑅
• Types of DAC
R/2R Ladder resistors

❑ Equivalent Ladder circuit


−𝑉𝑟𝑒𝑓 −𝑉𝑟𝑒𝑓
❑ 𝐼0 = =
2𝑅+2𝑅||2𝑅 3𝑅
• Types of DAC
R/2R Ladder resistors

Generally:
The equation of the output voltage
will be:
𝑫𝟎 ∗𝟐𝟎 +𝑫𝟏 ∗𝟐𝟏 +𝑫𝟐 ∗𝟐𝟐
𝑽𝒐 = 𝟐𝟑

Or:
• Types of DAC
R/2R Ladder resistors
• Comparison between
two types

Binary Weighted R-2R


Only 2 resistor values
Easier implementation
Pros Easily understood
Easier to manufacture
Faster response time
Limited to ~ 8 bits
Large # of resistors
Cons Susceptible to noise More confusing analysis
Expensive
Greater Error
• DAC
• Performance Specifications

❑Resolution
❑Errors
Resolution

Resolution: is the amount of variance in output


voltage for every change of the LSB in the digital input.
How closely can we approximate the desired output
signal(Higher Res. = finer detail = smaller Voltage
divisions)
A common DAC has a 8 - 12 bit Resolution

VRef
Resolution = VLSB = N
2 N = Number of bits
Errors
Offset Error:
Occurs when there is a constant
offset between the actual output
and the ideal output

.
Analog Output

Digital Input

Ideal Output Positive Offset Errorr Negative Offset Error


Errors

Resolution error:
Poor representation of ideal output
due to poor resolution
• APPLICATIONS
❑CD Players
❑MP3 Players
❑Digital Telephone/Answering
Machines
• APPLICATIONS
❑Function Generators

• Digital Oscilloscopes • Signal Generators


• Digital Input • Sine wave generation
• Analog Output • Square wave generation
• Triangle wave generation
• Random noise generation
•THE END
• Any question?

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