While the circuit diagram is the following: Circuit diagram of R-2R ladder DAC 3. The formula to find the Vo of the N-bits input is as the followings: The resistor values are no longer the problem.Accurate design is easy and possible to get no matter the N-bit inputs.Because this DAC type only uses two kinds of resistor values, the following advantages can be obtained by the users: The output analog voltage here is almost the same as the binary input using the R-2R ladder and added by the inverting adder circuit. This DAC type gives solutions to the weighted resistor DAC drawbacks. As the N-bits of digital input increase, it is harder to design more accurate resistors.The resistance values gap between MSB and LSB will grow higher as the N-bits of digital input increase.This DAC type has some drawbacks as it turns out: Here, because we use the 3-bit weighted resistor, the possible output voltage values will vary from the binary input of 000 to 111 referred to reference voltage VR. The formula above can be used to calculate the output voltage of the weighted resistor DAC. Thus, the nodal equation (Kirchoff’s Current Law) can be used in the inverting input as below. The inverting input will also equal zero volts following the virtual short concept.
It means that the non-inverting input is zero volts. The op-amp non-inverting input is connected to the ground.
Each of the digital switches (inputs) will equal zero if connected to the ground and equal one if it is connected to the negative reference voltage (-VR). The bit b 2 acts as the MSB (Most Significant Bit) and the bit b 0 acts as the LSB (Least Significant Bit). Suppose we have 3-bit inputs, represented by b 2, b 1, and b 0. Keep in mind that the binary digits only have 0 or 1 value. The inverting adder circuit is built by one op-amp unit. Weighted Resistor DACĪ weighted resistor DAC yields the analog signal output using the binary-weighted resistors that are added in the final process by the inverting adder circuit. The details are about to be explained in the DAC types section. The underlying working mechanism of DAC is not as simple as above truthfully. To get a basic understanding of DAC, you can see the following block diagram. A typical DAC has several binary digit (bit) inputs and a single analog output.
What is DAC?Ī DAC (Digital to Analog Converter) is an electronic device that converts the digital signal (binary) to the analog signal. The DAC could be found as a stand-alone DAC IC module or embedded into a microcontroller. The simplest situation is when you need to hear some music, there the DAC (Digital to Analog Converter) is playing its role to provide you the analog output for the music to be listened to by you. It is logical that the data conversion from the digital world into the analog world would be demanded by the people. However, the world we are living in at the moment is the analog world. It’s the reality that most of us already at least have a laptop, PC, or smartphone. We do agree that almost every aspect of our life is processed by the digital processing system.
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