This paper presents a resistor-less high-precision CMOS bandgap voltage reference (BGR). A high-order curvature compensation is applied to correct higher-order nonlinear temperature terms of the emitter-base voltage (VEB) and meet the high-precision request. With this nonlinearity correction method, the CTAT voltage VEB can be better linearized over a wide temperature range. Without using resistors, the offset voltage of the BGR output buffer is applied to yield the PTAT voltage. Using the proportionally weighted sum of negative temperature coefficient (TC) on VEB and positive TC on VOS, a highly stable bandgap voltage reference can be achieved. The proposed BGR is implemented in 0.18-μm CMOS technology. The active area of the prototype BGR is 300μm×440μm. A minimum TC of 2.5ppm/°C is achieved over a temperature range from −40°C to 85°C. The maximum total current is 26 μA over the supply voltage ranging from 1.6V to 2V. The BGR output is about 996mV with the power supply noise attenuation of −50dB.