R-2R DAC circuit (1)

*R-2R ladder* As its name implies, the “ladder” description comes from the ladder-like configuration of the resistors used within the network. An R-2R resistive ladder network provides a simple means of converting digital voltage signals into an equivalent analogue output. Input voltages are applied to the ladder network at various points along its length and the more input points the better the resolution of the R-2R ladder. The output signal as a result of all these input voltage points is taken from the end of the ladder which is used to drive the inverting input of an operational amplifier. Then a R-2R resistive ladder network is nothing more than long strings of parallel and series connected resistors acting as interconnected voltage dividers along its length, and whose output voltage depends solely on the interaction of the input voltages with each other.