A Nanowatt Temperature-Independent Tunable Active Capacitance Multiplier with DC Compensation in 0.13-mu m CMOS

This paper presents a nanowatt active capacitance multiplier (ACM) with enhanced tunable capacitance multiplication factor and temperature-independent current control for Artificial Internet of Things (AIoT) sensor applications. The proposed circuit is based on secondgeneration voltage conveyor (VCII) topology and biased in subthreshold region for high energy efficiency. An improved stacked translinear loop is designed to achieve temperature-independent bias with reduced power consumption. A DC compensation circuit is incorporated to compensate the output DC offset due to active bias circuit current, so that ACM can directly interface with other ultra-low power circuits. The proposed circuit is implemented in a standard 0.13-mu m CMOS process. Simulation results show that the 3-dB bandwidth is from 0.04 Hz to 8 kHz and the multiply factor can be tuned from 337 to 561 with power consumption in the range of 41.6 nW to 46.4 nW. The achieved figure-of-merits (FoMs) is compared favorably with the other state-of-the-arts.