digital to analog (DAC) & analog to digital converter (ADC)

these slides contain a detailed description of DAC & ADC. with the help of PowerPoint animations i have tried to explain the operation and performance of the circuits in detail.

1. OP-AMP applications UNIT-5 Mohammad Asif Iqbal Assistant Professor, Deptt of ECE, JETGI, Barabanki

2. Need of conversion

3. Basic concept for Digital to Analog conversion Have a look at Binary to Decimal conversion So in order to convert digital data into analog we need a circuit which is capable of producing output similar to this.

4. DAC Specializations Vref So from the previous expression we may conclude that our Vo is a function F of Vref . Vo = F × Vref Consider an N-bit data, So, total number of combinations = 2^N The resolution of either a digital-to-analog converter (DAC) or an analog-to-digital converter (ADC) is the measure of how finely its output may change between discrete, binary steps. More number of combinations mean more number of levels…

5. Binary weighted DAC 1 1

6. At output you will be getting that pulse as long as output of the comparator is high. Dual slop ADC(SLOW) Here two points are worth noting. We will use the concept of virtual ground No current will flow inside the Op-Amp Do u remember? Its a simple comparator. Comment about its output….. At output you will be getting that pulse as long as output of the comparator is high. Its your counter V1 V2 t V2 > V1 t 1 t 2 Here you can observe , we have fixed count with variable slop. At output you will be getting that pulse as long as output of the comparator is high. Here the count is different but the slop is constant . Why?? Give the reason of this negative slop.

7. Flash type ADC (FASTEST) 8V 7 V 6 V 5 V 4 V 3 V 2 V 1 V Voltage divider network Comparator Parity encoder 3.5V 1 1 1 1 1 Why/how??

8. Successive approximation DAC(Trade off between speed and hardware) comparator Its a simple DAC SAR 3.5V 1000 1 0 0 0 8 0100 1 0 0 4 0010 1 2 1 0011 0 1 1 3 0011

9. THANK YOU!