13-04-2013, 04:55 PM
STUDY OF DIGITAL TO ANALOG CONVERTER & ANALOG TO DIGITAL CONVERTER
AIM:
To design 1) weighted resistor DAC
2) R-2R ladder Network DAC
THEORY:
Digital systems are used in ever more applications, because of their increasingly efficient, reliable, and economical operation with the development of the microprocessor, data processing has become an integral part of various systems Data processing involves transfer of data to and from the micro computer via input/output devices. Since digital systems such as micro computers use a binary system of ones and zeros, the data to be put into the micro computer must be converted from analog to digital form. On the other hand, a digital-to-analog converter is used when a binary output from a digital system must be converted to some equivalent analog voltage or current. The function of DAC is exactly opposite to that of an ADC.
A DAC in its simplest form uses an op-amp and either binary weighted resistors or R-2R ladder resistors. In binary-weighted resistor op-amp is connected in the inverting mode, it can also be connected in the non inverting mode. Since the number of inputs used is four, the converter is called a 4-bit binary digital converter.
PROCEDURE:
1. Connect the circuit as shown in Fig 1.
2. Vary the inputs A, B, C, D from the digital trainer board and note down the output at pin 6. For logic „1‟, 5 V is applied and for logic „0‟, 0 V is applied.
3. Repeat the above two steps for R – 2R ladder DAC shown in Fig 2.