The r2r network consists of resistors with only two values r and 2xr. Similarly it can be found that using above process for bit 0100 the output will be v r 4, for bit 0010 output will be vr8 and for bit 0001 output will be vr16 by using superposition theorem we can find in any nbit ladder network the. The most popular networks are the binary weighted ladder and the r 2r ladder. The following circuit diagram shows the basic 2 bit r2r ladder dac circuit using opamp. Dac a reference input in 2quadrant mode, r2 terminal in 4quadrant mode. The circuit can be viewed as a voltagemode digitaltoanalog converter dac or a programmable attenuator operating on the signal. Fixed resistors r2r ladder networks application note. R2r ladder dac wide lange of resistors are required in binary weighted resistor type dac. This is the output change that would occur for a change in the least significant bit. Both resistor string dac and r2r ladder dac are resistive type. The r2r ladder dac makes use of only two resistor valuesbut it requires 2 n resistors to implement an nbit converter. The r2r ladder the r2r ladder dates to the 1960s, as exemplified by the circuit shown in figure 1 1. Digital to analog conversion the r2r dac tektronix. Digital to analog converter topics of discussion digikey.
Joint pdf of a random variable affected by two uniformly. In this video, r2r ladder type digital to analog converter has been explained with a solved example. R2r ladder networks application note fixed resistors. Pdf a mostonly r2r ladderbased architecture for high. In the voltage mode r2r ladder dac shown in figure 5, the rungs or arms of the ladder are switched between vref and ground, and the output is taken from. Equivalent offset voltage at the input of the gain stage a, and the same. R2r ladder da converter electronics engineering study. R2r ladder dac explained with solved example youtube.
The resolution of the ladder is the smallest possible output change r2r ladder networksapplication note fixed resistors for any input change to the ladder and is given by 12n where n is the number of bits. An enhancement of the binaryweighted resistor dac is the r2r ladder network. One of the most common dac buildingblock structures is the r2r resistor ladder network shown in figure 4. R2r ladder a resistorstring dac n1 i 0refi1 i0 b vv 2. A mostonly r2r ladder based architecture for high linearity dacs. Pdf an r2r ladderbased architecture for high linearity dacs. B1 b0 the typical value of feedback resistor is rf 2r. This can be avoided by using r2r ladder type dac where only. This type of dac utilizes thevenins theorem in arriving at the desired output voltages.
Pdf digital to analog conversion performance is mainly. The r2r ladder is connected to an external reference input vref that. Dac prototype 2 tests at ihp and kt performed measurements. Chapter 2 introduction to digital to analog converter university of.
The number of digits per binary word is assumed to be two i. The r2r resistor ladder network directly converts a parallel digital symbolword. Now at n4, if we calculate the output analog equivalent voltage then we will get. Here, resistors 7881 are equal to r, and 7177 are equal to 2r, with units 6064 acting as switches. As this subdac is a purely binary weighted so an r2r ladder network is.