Your first assignment as an engineer is to write a product description for a new

Question

Your first assignment as an engineer is to write a product description for a new 4-bit digital-to-analog resistance ladder. Because of the mask tolerances in VLSI chips, each resistor shown below is guaranteed to be only within 3 % if its nominal value. That is, if R_o is the nominal design resistance, then each resistance labeled R can have a resistance anywhere in the range (1 plusminus 0.03) R_0 and each resistance 2R can have a resistance anywhere in the range (2 plusminus 0.06) R_0. You are to write an honest description of the accuracy of this product. Remember that if you overstate the accuracy, your company will have many returns from dissatisfied customers, whereas if you understate the accuracy, your company won't have any customers.

Explanation / Answer

This is an R-2R ladder network used in digital to analog conversion circuits.

This is the easy and widely used network for DAC.

There is no problem as far as tolerance of 3% considered for a resistor R.

To calculate the value of VA ,

We consider the contribution of each voltage source,

let, V1=V2=V3=V4

VA = 4 x [R /(2R +R)] V1 .... contribution of all 4 voltage sources

VA = (4/3) V1

this gives the value of output voltage of the R-2R ladder which is independent of the resistance value as long as they all are same.

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