Full compensated Depletion-Mode MOS-Capacitor for pure digital technology low voltage switched-capacitor applications

A full compensated depletion-mode MOS capacitor is presented in this article. The capacitor is composed of MOS depletion capacitors which are biased appropriately to extend available usable voltage range. The capacitor is suitable for state-of-art technology and low-voltage switched capacitor applications. Completely digital technology cuts the cost down heavily. The voltage-dependence and temperature-dependence of the capacitor are much smaller compared with series and parallel compensated depletion-mode MOS capacitors. Theoretical analysis and HSPICE simulations show that the capacitor achieves a density of 0.52 fF/mum² and a temperature-dependence coefficient of 0.096 ppm/C. A much smaller voltage-dependence square coefficient of 57.2 ppm/V makes it superior in full differential switched-capacitor applications.