Design of a Precision Low Voltage Resistor Multiplying Digital-to-Analog Converter

Abstract

This work aims to model the effect of the input offset voltage of an operational amplifier on the performance of a high-precision, voltage-mode, resistor-based multiplying digital-to-analog converter (M-DAC). Based on the model, a high precision current buffer is proposed to isolate the resistor ladder from the operational amplifier. A 14-bit M-DAC operating with a ±1V reference of the proposed architecture. Post-layout simulations show that the proposed architecture reduces the offset voltage to an offset error in the DAC transfer function. The maximum DNL is maintained at -0.385 LSB for an input offset voltage of up to 60mV (1024 LSB). The current buffer also introduces an inversion of the output voltage, yielding a non-inverted output. This alleviates the need for an additional high precision op-amp to invert the output voltage.