DIGITAL TO ANALOG CONVERTER

A digital to analog converter having a pair of resistor strings. A first one of the resistor strings is adapted for coupling across a voltage supply. Resistors in the first resistor string produce voltages in response to current fed thereto from the voltage supply. A first switching network couples a voltage produced across a selected one of resistors in the first string across the second resistor string. The resistors in the second resistor string produce voltages in response to current passing from the first resistor string to the second resistor string through the first switching network. That is, the second resistor string is unbuffered from the first resistor string. A second switching network couples a selected one of the voltages produced at a selected one of the resistors in the second resistor string to an output. The resistance across the second resistor string is larger than the resistance of the selected one of the resistors in the first resistor string thereby reducing the loading effect of the second resistor string without requiring buffer amplifiers between the pair of resistor strings. In a preferred embodiment of the invention the resistances of the second mentioned string and the switching networks are selected to produce a step change of substantially one LSB, where LSB is the least significant bit of a digital word converted by the converter.