D/A Converter

There are several methodes and circuits for producing the D/A converter that has been described. Figure (a) shows the basic circuit for one of type of four – bit DAC. The inputs A, B, C, and  D are binary input that are assumed to have values of either 0 or 5 V. The operational amplifier show as summing amplifier operation. The function of Rf is R feed back. The D input has R_IN 1 KΩ, so the summing amplifier passes the voltage at D with no attenuation. The C input has R_IN 2 KΩ, so that it will be attenuated by ½. Similarly, the B input will be attenuated by ¼, and the A input by 1/8. The amplifier output can thus be expressed as

figure a. D/A Converter

Logic 0 = 0V

Logic 1 = 5V