Compensation for voltage dependence of diffused feedback resistors in operational amplifiers

A simple and useful method is proposed to decrease the nonlinearity of the diffused resistors used in the feedback loop of an operational amplifier. The voltage dependence of the diffused resistor is decreased by controlling the potential of the island containing the resistor. An application to improve the linearity of the output amplifier in D/A converters is described. The method allows the diffused feedback resistors to have a linearity of better than 0.005 percent accuracy.