This paper presents a high-resolution voltage reference which is suitable for building high-precision magnet power supplies for accelerators. it consists of digital signal processor, field programmable gate array, and two digital-to-analog converter (DAC) boards. The DAC board uses two commercial 16-bit-D/A converters and an analog signal processing circuit to achieve a resolution higher than 20-bit. The proposed voltage reference has a resolution of 20-bit (1 ppm) for the +10V full scale. The short- and long-term stabilities are similar to 1 and 5ppm, respectively. The controllability and reproducibility of the output voltage to a step input were similar to 1 ppm (10 mu V). The equivalent bandwidth of the voltage reference was similar to 5 kHz. These experimental results show that the proposed voltage reference may be applied to many other systems which require a high-resolution and cost-effective voltage reference with a good long-term stability. The voltage reference can be interfaced with the Ethernet (including EPICS), CAN, and RS232C. (C) 2009 Elsevier B.V. All rights reserved.