A novel low-power MOS-only voltage reference is presented. The Enz–Krummenacher–Vittoz (EKV) model is adopted to provide a new perspective on the operating principle. The normalized charge density, introduced as a new variable, serves as an indicator when trimming the output temperature coefficient. The proposed voltage reference consists of a specific current generator and a 5-bit trimmable load. Thanks to the good match between the current source stage and the output stage, the nonlinear temperature dependence of carrier mobility is automatically canceled out. The circuit is designed using 55 nm COMS technology. The operating temperature ranges from −40 °C to 120 °C. The average temperature coefficient of the output voltage can be reduced to 21.7 ppm/°C by trimming. The power consumption is only 23.2 nW with a supply voltage of 0.8 V. The line sensitivity and the power supply rejection ratio at 100 Hz are 0.011 %/V and −89 dB, respectively.