A straightforward 4-bit computerized to-simple converter that is built from a carefully controlled switch (74HC4066), an arrangement of paired weighted resistors, and an operational enhancer. The fundamental thought is to make an upsetting enhancer circuit whose pick up is controlled by changing the information opposition Rin. The 74HC4066 and the resistors together go about as a carefully controlled Rin that can go up against one of 16 conceivable qualities. (You can think about the 74HC4066 and resistor mix as a carefully controlled current source. Each new parallel code connected to the contributions of the 74HC4066 produces another discrete current level that is summed by RF to give another discrete yield voltage level.) We pick scaled resistor estimations of R, R/2, R/4, and R/8 to give Rin discrete qualities that are similarly separated. To locate every single conceivable estimation of Rin, we utilize the recipe gave. This recipe resembles the old resistors-in-parallel equation, yet we should bar those resistors which are not chosen by the computerized input code-that is the thing that the coefficients A through D are for (a coefficient is either 1 or 0, contingent upon the advanced information)
Presently, to locate the simple yield voltage, we basically utilize Vout = −Vin (RF/Rin)- the articulation utilized for the rearranging enhancer indicates what we get when we set Vin = −5 V, R = 100 kω, and RF = 20 kω, and take all conceivable info codes. The double weighted DAC appeared above is restricted in determination (4-bit, 16 simple levels). To twofold the determination (make a 8-bit DAC), you may think to include another 74HC4066 and R/16, R/32, R/64, and R/128 resistors. In principle, this works; in all actuality, it doesn't. The issue with this approach is that when we achieve the R/128 resistor, we should locate a 0.78125-kω resistor, accepting R = 100 kω. Accepting we can discover or develop a proportional resistor organize for R/128, we're still in a bad position on the grounds that the resiliences of these resistors will mess things up. This scaled-resistor approach winds up unfeasible when we manage resolutions of in excess of a couple of bits.
To expand the determination, we scrap the scaled-resistor organize and supplant it with a R/2R stepping stool arrange the producers of DAC ICs do this too. A R/2R DAC utilizes a R/2R resistor stepping stool organize rather than a scaled-resistor arrange, just like the case in the past DAC. The advantage of utilizing the R/2R stepping stool is that we require just two resistor esteems, R and 2R. The secret to seeing how the R/2R step functions is understanding that the current drawn through any one switch is dependably the same, regardless of in the event that it is hurled or tossed down. In the event that a switch is tossed down, current will course through the switch into ground (0 V). In the event that a switch is hurled, current will stream toward virtual ground-situated at the operation amp's upsetting information (review that if the non reversing contribution of an operation amp is set to 0 V, the operation amp will influence the modifying to enter 0 V, through negative input). When you understand that the current through any given switch is constantly steady, you can assume that the aggregate current (I) provided by Vref will be consistent too. Once you have that, you make sense of what portions of the aggregate current goes through each of the branches inside the R/2R organize utilizing basic circuit examination.
Presently, to locate the simple yield voltage, we basically utilize Vout = −Vin (RF/Rin)- the articulation utilized for the rearranging enhancer indicates what we get when we set Vin = −5 V, R = 100 kω, and RF = 20 kω, and take all conceivable info codes. The double weighted DAC appeared above is restricted in determination (4-bit, 16 simple levels). To twofold the determination (make a 8-bit DAC), you may think to include another 74HC4066 and R/16, R/32, R/64, and R/128 resistors. In principle, this works; in all actuality, it doesn't. The issue with this approach is that when we achieve the R/128 resistor, we should locate a 0.78125-kω resistor, accepting R = 100 kω. Accepting we can discover or develop a proportional resistor organize for R/128, we're still in a bad position on the grounds that the resiliences of these resistors will mess things up. This scaled-resistor approach winds up unfeasible when we manage resolutions of in excess of a couple of bits.
To expand the determination, we scrap the scaled-resistor organize and supplant it with a R/2R stepping stool arrange the producers of DAC ICs do this too. A R/2R DAC utilizes a R/2R resistor stepping stool organize rather than a scaled-resistor arrange, just like the case in the past DAC. The advantage of utilizing the R/2R stepping stool is that we require just two resistor esteems, R and 2R. The secret to seeing how the R/2R step functions is understanding that the current drawn through any one switch is dependably the same, regardless of in the event that it is hurled or tossed down. In the event that a switch is tossed down, current will course through the switch into ground (0 V). In the event that a switch is hurled, current will stream toward virtual ground-situated at the operation amp's upsetting information (review that if the non reversing contribution of an operation amp is set to 0 V, the operation amp will influence the modifying to enter 0 V, through negative input). When you understand that the current through any given switch is constantly steady, you can assume that the aggregate current (I) provided by Vref will be consistent too. Once you have that, you make sense of what portions of the aggregate current goes through each of the branches inside the R/2R organize utilizing basic circuit examination.
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