DAC Example Problem

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DAC Instance Downside

Within the earlier chapter, we mentioned the 2 forms of DACs. This chapter discusses an instance downside based mostly on R-2R ladder DAC.

Instance

Allow us to discover the worth of analog output voltage of R-2R Ladder DAC for a binary enter, b2b1b0b2b1b0 = 100.

Circuit Diagram and its Simplification

The circuit diagram of a 3-bit R-2R Ladder DAC when binary enter, b2b1b0b2b1b0 = 100 utilized to it’s proven within the following determine −

Simplification

Within the above circuit, there exists sequence and parallel combos of resistors to the left of level A with respect to floor. So, we are able to substitute that whole resistor community with a single resistor having resistance of 2RΩ2RΩ.

The simplified circuit diagram is proven within the following determine −

Simplified Circuit Diagram

We are able to substitute the a part of the community that’s linked to the left of level B with respect to floor through the use of a Thevenin’s equal circuit. The modified circuit diagram is proven within the following determine −

Modified Circuit Diagram

Within the above circuit, there exist a sequence mixture of two resistors. Exchange this mixture with a single resistor. The ultimate circuit diagram after simplification is proven within the following determine −

Final Circuit Diagram

Now, the above circuit diagram appears like an inverting amplifier. It’s having an enter voltage of VR2−VR2 volts, enter resistance of 2RΩ2RΩ and suggestions resistance of 2RΩ2RΩ.

The output voltage of the circuit proven above will probably be −

V0=2R2R(VR2)V0=−2R2R(−VR2)
V0=VR2V0=VR2

Due to this fact, the output voltage of 3-bit R-2R Ladder DAC is VR2VR2 volts for a binary enter, b2b1b0b2b1b0 = 100.