An energy harvesting (EH) system with incremental step sensing (ISS) maximum power point tracking (MPPT) algorithm is presented in this work. The ISS-MPPT algorithm is generic for any discontinuous conduction mode (DCM) based converter independent of the type, topology, and control of the converter and converter parameters. The problem in implementing a successive approximation register (SAR) inspired algorithm for MPP hill climbing is rectified by our proposed adaptive step-size-based approach for fast-tracking. A resistor or current-sensor less, time-based, input current sensing technique is proposed to generate a voltage inversely proportional to the input current. The chip-prototype is fabricated in a standard 180 nm CMOS technology occupying 1.17 mm2 of silicon area. The fabricated chip is a single inductor-single input dual output boost converter (SI-SIDO) which caters to an input power range of 30 $\mu \text{W}$ to 33 mW and an input voltage range of 150 mV to 1.8 V. The proposed system is compatible with photo-voltaic (PV) and dc output (like thermal transducers, bio-fuel cells)-type sources achieving up to 99.5% MPPT efficiency. The chip achieves an MPPT efficiency of not less than 95% in the case of a dc input source with 300 mV to 0.8 V open circuit voltage ( $V_{\mathrm{ OC}}$ ) and 25– $500 \Omega$ of input resistance ( $R_{\mathrm{ IN}}$ ) in measurements. A peak converter efficiency of 88% is achieved with a quiescent power consumption of 1.8 $\mu \text{W}$ with the MPP module consuming 440 nA of current.