Patent ID: 7136002

Claim:
A digital to analog converter (DAC), comprising: a pair of resistor strings, a first one of the resistor strings being adapted for coupling across a voltage supply, resistors in the first resistor string producing voltages in response to current fed thereto from the voltage supply and a second one of the resistor strings; a switching network adapted to couple a voltage produced across a selected one of resistors in the first string across the second one of the resistor strings in response to a digital input signal, said digital input signal comprising a digital bit stream, the resistors in the second resistor string producing voltages in response to current passing from the first resistor string through the second resistor string through said switching network to produce a corresponding analog signal to said digital input signal to an output; and wherein the switching network is adapted to provide an unloaded state generated when a Least Significant Bit (LSB) resistor of said DAC, associated with said first resistor string, is de-coupled from a Most Significant Bit (MSB) resistor of said DAC, associated with said second resistor string, of said digital input signal by said switching network.