A 1 MHz, Synchronous, Step-down from 3.6 V to 1 V, PWM CMOS DC-DC Converter with more than 80% of Power Efficiency

Yasuhiro SUGIMOTO  Shinichi KOJIMA  

IEICE TRANSACTIONS on Electronics   Vol.E87-C   No.3   pp.416-422
Publication Date: 2004/03/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Electronic Circuits
step-down DC-DC converter,  1 MHz operation,  1 V output,  power efficiency,  PWM,  

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This paper introduces a power-efficient on-chip DC-DC converter, which produces a 1.0 V output by being stepped-down from a 3.6 V input, utilizes a 10 µH external inductor, and realizes more than 80% power-efficiency. In order to realize a 1.0 V output without decreasing power-efficiency, a synchronous-type rectifier scheme with a reverse current protection circuit is adopted and a reference voltage of less than 1.0 V is developed. The external inductor value is reduced by applying the PWM control scheme and a new low-power 1 MHz triangular waveform oscillator. High-value resistors are used in analog circuits including a voltage reference, a triangular waveform oscillator, an error amplifier, and a comparator to have the ultra-low power characteristics. A chip is actually designed and fabricated by using the 2 µm CMOS process. As a result, a 1 MHz, synchronous, step-down from 3.6 V to 1 V, PWM DC-DC converter has been realized with a power efficiency of more than 80% in the output current range from 40 to 70 mA.