Patent ID: 7843261

Claim:
An apparatus comprising: an amplifier having a first input node, a second input node, and an output node, wherein the amplifier receives an input signal at the first input node; a resistor network that is coupled to the output node of the amplifier, wherein the resistor network includes a plurality of resistors coupled in series with one another and a plurality of first tap nodes, wherein the resistor network further comprises five resistors, wherein the values of the five resistors are integer multiples of one another; an R-2R network that is coupled to the resistor network, wherein the R-2R network includes a plurality of second tap nodes; and a plurality of switches, wherein at least one switch is coupled between the second input node of the amplifier and each first tap node, and wherein at least one switch is coupled between the second input node of the amplifier and each of the second tap nodes.