On-chip digital inductor current sensor for monolithic digitally controlled DC-DC Converters

Inductor current information can be used by digitally controlled DC-DC converters as control signal or over-current protection. In most of the existing approaches, the digital inductor current-sensing and quantization are always designed and implemented as two separated functional blocks, e.g. an analog current sensor and an ADC. This is actually a redundant approach and designing a high-gain amplifier in deep sub-micron process is power consuming. Therefore, this paper proposed an on-chip digital inductor current sensor which combines both the sensing and quantization into a single functional block. In this way, chip area and power consumption can be saved. An 8-bit digital inductor current sensor for 4MHz buck converter is designed and implemented. Simulation results show that the sensor has linear and monotonic properties with LSB of 2.7mA.