TABLE OF CONTENTS Many measuring systems measure in analog form and all the physical quantities exist in analog form. Today, however, all the processing is done through computers which use digital technology. Hence, there is a need to convert analog data to digital data and vice versa.
This is why we need Digital to Analog Converters (DAC) and Analog to Digital Converters (ADC). As a group, they are Data Converters.
The DAC output can be either in the form of current I 0 or in the form of voltage V 0.
For this example, output in voltage is considered. The output voltage can be written:
| (7.1) |  |
| where V 0 = | output voltage |
| K = | multiplication factor, i.e., scale factor |
| V FS = | output voltage for maximum input, i.e., full-scale output voltage |
| d 1, d 2 ... d n = | n-bit binary word |
| d 1 = | most significant bit of binary word |
| d n = | least significant bit of binary word |
The different techniques available for DACs are discussed below.
A weighted resistor DAC uses n switches for n different bits of binary word. It uses an operational amplifier in inverting amplifier mode and the resistors which are placed in different paths are multiplied by 2. This circuit is shown in Figure 7.2.
| (7.2) |  |
The major...
