A high linearity MOS capacitor for low voltage applications

MOS capacitor with high linearity is proposed in this paper, which approves excellent voltage dependence and temperature-dependence. The capacitor achieves a density of 0.52fF/μm² and a temperature-dependence coefficient of 0.096ppm/C, voltage-dependence square coefficient of 57.2ppm/V. A analog to digital modulator in SMIC 0.18μm logic technology is designed with this capacitor, which achieves 16bits resolution with 1.2V supply voltage. This MOS capacitor is approved to be good choice in mixed signal designs in SOC, which allows the whole chip to be realized in standard logic technology.