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Conventionally, inductor current is sensed and quantized before it can be used by digitally controlled DC-DC converters. These are intuitively done by using two separated functional blocks—an analog current sensor and an ADC. A few research works have investigated other ways of obtaining the inductor current information in the digital domain. This paper proposes an on-chip digital inductor current sensor that combines both the inductor current-sensing and quantization into a single functional block. In this way, the redundancies found in the conventional approach can be reduced and optimizations can be made to save chip area and power consumption. An 8-bit digital inductor current sensor has been designed and fabricated with a UMC 0.13~\mum CMOS process. The measurement results show that the digital sensor can provide digital inductor current information with a conversion time of 225 ns. This can be used by a buck converter with a switching frequency up to 4 MHz. The digital sensor has linear and monotonic input-output transfer curve properties with an LSB of 6.79 mA. It consumes current of 700~\muA at 1.2 V supply voltage. [ABSTRACT FROM PUBLISHER]

An output voltage ripple aware design of different voltage ramp signal of voltage-mode CCM random frequency buck converter for conductive EMI reduction is presented. A mathematical analysis has been carried out to model the output voltage ripple of random switching converter. Simulations of the converter have been undertaken and measured results from the converter fabricated with a standard 0.35 \mum CMOS process verify the proposed design approach. From experimental results, a carefully designed ramp can reduce the output voltage ripple by more than 8 times without significant influence on the inductor current spectrum spread and any increment on the output filtering inductance and capacitance comparing to the conventional design. [ABSTRACT FROM AUTHOR]