A Nanowatt Temperature-Independent Tunable Active Capacitance Multiplier with DC Compensation in $0.13-\mu\mathrm{m}$ 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 second-generation 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 $0.13-\mu\mathrm{m}$ 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.