Implementation of D/A Converter

Experiment No.: 6(A)

Experiment Name:

Implementation of Digital to Analog converter using trainer kit.

Objective:

To design and study the digital to analog converter.

Theory:

A digital-to-analog converter (DAC or D-to-A) is a device that converts a digital (usually binary) code to an analog signal (current, voltage, or electric charge). A typical DAC converts the abstract numbers into a concrete sequence of impulses that are then processed by a reconstruction filter using some form of interpolation to fill in data between the impulses.

There are two types D/A converter

Weighted resistor D/A converter
D/A converter with ladder N/W.

WEIGHTED D/A CONVERTER:- The binary weighted resistor DAC uses an op- amp to sum n binary weighted currents from a reference voltage V_R via current scaling resistor 2R, 4R, 8R, ……2ⁿR. A weighted resistor DAC requires a wide range of resistor values for better resolution whereas a R-2R ladder type DAC requires only two values of resistor .
D/A CONVERTER WITH LADDER N/W:- In this type reference voltage is applied to one of the switch position , and other switch position is connected to ground .The number of bits can be expanded by adding more sections of same R/2R values.

Circuit Diagram:

Procedure: Functional verification of a weighted resistor D/A converter.

Make the connection as shown in circuit diagram.
Connect the power supply to the board.
Connect the logic switches to the corresponding jacks B₀ – B₃ of the converter.
Set the switches S₀ – S₃ to logic level 0.
Connect the V_ref socket to +5 volts.
Connect a multimeter as voltmeter for DC, to the output V_o of the converter.
Switch the logic switches in binary progression & measure & record the output voltage in correspondence of every Combination of the input code.

Observation Table:

Sl. No.	S₃	S₂	S₁	S₀	V_O (Volt)
1.	0	0	0	0	0.02
2.	0	0	0	1	1.2
3.	0	0	1	0	1.98
4.	0	0	1	1	3.36
5.	0	1	0	0	4.87
6.	0	1	0	1	5.03

Apparatus Used:

Sl. No.	Name of the Apparatus	Specification	Quantity	Maker’s Name
1.	DAC Trainer Kit	230 V input	1	Excel
2.	Patch Cord		As required
3.	Digital Multimeter	0-750 V AC, 0-1000 V DC, 0-10 A	1	Akademika

Result:

The DA converter is studied & observations are recorded in observation tables.

Precaution:

All the connections should be right and made according to connection diagram. Switched on the power supply after checking the connections. Reading should be taken carefully consciously.