This paper presents a high-efficiency, ultra-low-power automated on/off adaptive MPPT (AOA-MPPT) system for microscale energy harvesters. It is designed to extract the maximum available power from photovoltaic (PV), radio frequency (RF), and thermoelectric generator (TEG) energy sources. AOA-MPPT combines a power-change detector (PCD) that activates tracking only when input power changes (auto-on) with an auto-off convergence detector that halts perturbation at lock and powers down MPPT circuitry, eliminating steady-state dither and lowering controller power. Input power is estimated from a single sample of the inductor peak current, enabling duty-cycled sensing with low sensitivity to converter gain. A low-power, wide-range PWM control (LS-PWM) provides broad duty-cycle adjustment of the inductor charge time, enabling input impedance matching for maximum power transfer. The AOA-MPPT circuit is designed along with a boost converter and fabricated in 65nm CMOS technology. It achieves a peak tracking efficiency of 99.9%, a peak converter efficiency of 87%, and a power consumption of only 112nW.

This paper presents a maximum power point tracking (MPPT) circuit for DC-DC converters which is well suited for DC energy harvesters. To save the power of the tracking circuit when there is no variation in the input power, a power change detector (PCD) circuit is also proposed in the MPPT circuit. With PCD, changes in the input power are detected, thereby activating the MPPT circuitry for tracking. When MPP is achieved, the proposed logic shuts down the MPPT-related circuits to save power. A modified hill-climbing (HC) technique is implemented for the tracking algorithm to address the speed/precision tradeoff. The MPPT circuit uses a power estimation method based on sensing and sampling of the inductor peak current, achieving a high tracking efficiency. The proposed MPPT system is designed in 65nm CMOS technology. Simulation shows a peak tracking efficiency (TE) of 99.9% is achieved without oscillation of the operating point. The power consumption of the proposed MPPT circuit is 125nW.

Emerging Analog Trojans such as A2, large-delay Trojans, and row-hammer have been shown to be more stealthier than previously known digital Trojans. They are smaller sized, do not rely on inputs for triggering, and the trigger for their payload can be made arbitrarily delayed, like a ticking time bomb. Furthermore, analog Trojans can easily evade detection due to their novel nature and incompatibility with the digital design and validation flow. In this paper, we propose a current signature-based detection scheme, which can effectively catch various analog Trojans at both run-time and production time validation. The paper includes techniques that advance Trojan detection method through incorporating detection of transient variation in the power supply current. Proposed current-sensor can sense currents down to 10s of nano-Amps improving over prior power sensing based techniques. Further, a configurable design of current sensor is developed to enable large range sensing capability. The design is also developed to be compatible with the digital design flow and can be logic obfuscated. This detection method can be used at run-time to potentially fence off activation of analog Trojans in the field through early warning signals. The commercial 65nm CMOS technology is utilized to verify the proposed idea.