Low-power/low-voltage integrated CMOS sense resistor-free analog power/current sensor compatible with high-voltage switching DC-DC Converter

A sensor circuit to measure the output power of a dc-dc boost for photo-voltaic (PV) maximum power point tracking (MPPT) application is presented. The proposed approach obviates the need for a series current sense resistor and a complex current/voltage digitization and multiplication circuitry required for calculating power. Thereby, this technique does not require analog multipliers, analog-to-digital converters, digital signal processor, and FPGA, thus reducing the bill of material, silicon area, and power consumption of the overall system. Additionally, it provides the dc electrical isolation between the high output voltage of the boost converter and the low-voltage integrated CMOS power sensor circuit. The proposed power sensor circuit is implemented using a switched capacitor differentiator and a voltage-to-time converter. This approach results in lower complexity, lower silicon area, lower power consumption, and lower component count for the overall PV MPPT system. Designed in a 180-nm CMOS process, the circuit can operate with a supply voltage of 1.8 V. It achieves a power sense accuracy of 7.6%, occupies a die area of 0.0519 mm², and consumes a power of 0.748 mW.