A 12-bit CMOS Dual-ladder Resistor String D/A Converter Integrated with Self-adjusted Reference Circuit

摘要

This paper presents a 12 bit dual-ladder resistor string digital to analog converter (DAC) with the power supply of ±5V which adopts a self-adjusted reference circuit and a class-AB output buffer. A self-adjusted reference circuit is used to provide differential reference voltages for obtaining better accuracy and symmetry. The DAC reuses the resistors of the differential reference voltages circuit as the dual-ladder resistor string, which saves a considerable chip area. Class-AB output stage is employed to reduce the setup time and enhance the load-driving capability. The 12 bit DAC is fabricated in a standard 0.5μm CMOS process. The measured results show that the integral non-linearity (INL) and differential non-linearity (DNL) are less than 2 LSB and 0.25 LSB, respectively. The proposed DAC features the characteristics of high precision, good monotonicity and excellent symmetry.