This work presents the design of a low-complexity FPGA-based maximum power point tracking (MPPT) circuit for wide power range light-energy harvesting applications. The circuit relies on a self-oscillating dc-dc boost (SOB) converter for the power conversion, which is controlled via an analog voltage. A custom-made digital-to-analog (D/A) converter circuit is used to produce the required analog voltage, while a resistor-free current-to-frequency (C/F) converter circuit provides feedback of the SOB converter's output power. The FPGA-based digital part of the circuit controls the D/A converter and implements the perturb and observe MPPT logic using the frequency feedback of the C/F converter. The circuit was constructed and measured using discrete components. The digital MPPT control has been described in Verilog HDL and implemented on an Intel Cyclone 10CL016 FPGA. The circuit works in a very wide input power range from 15 uW up to 1 W with constant efficiency and is suitable for light energy harvesting both at indoor and outdoor lighting conditions. Experimental results prove this implementation to be suitable for on chip integration.