A CMOS-Control Rectifier for Discontinuous Conduction Mode Switching DC-DC Converters ISSCC 2006 / SESSION 19 / ANALOG TECHNIQUES / 19.8 Tsz Yin Man, Philip K.T. Mok and Mansun Chan Class presentation: Davood Amerion University of Tehran 28 December 2006

Preliminary

Power Supply topology 1- isolated - Push-pull (Half/full bridge) - Fly back 2- non isolated - Buck converter - Boost converter - Buck-Boost converter

Boost Converter [2]

Operating modes [2] :. - Discontinuous current mode Operating modes [2] : - Discontinuous current mode - Continuous current mode

MOTIVATION The power efficiency and inductor profile of switching dc-dc converters are two of the most important issues in modern battery powered mobile systems. Discontinuous-conduction mode (DCM) operation enables both a reduction in the switching losses and the use of a small inductor in the high switching frequencies (10s to 100s of MHz). In this paper, a CMOS-Control Rectifier (CCR) is proposed to simultaneously provide adaptive dead time control and mV-range forward-voltage drop for sub-1V highly efficient DCM switching dc-dc converters employed in single cell battery-powered mobile systems.

CCR diagram [1]

Results [1] Technology 0.35μm 2-poly 4-metal CMOS technology. 1μH inductor. comparators in the proposed CCR facilitates nanosecond response times, TON (~20ns) and TOFF (~60ns) the proposed CCR provides mV-range forward-voltage drop and the conduction loss is significantly lower than silicon or Schottky diodes regulated output voltage of 2.5V with 100mA maximum output current. The input voltage range is from 0.9 to 1.2V. a 4.7μF output capacitor and a 1μH inductor are used to facilitate the application of the entire boost converter to modern pocket-size, or even thumb-size, mobile systems. Maximum power efficiency of ~ 87% is achieved at 100mA output current and 1.2V input voltage.

References: [1] ISSCC 2006 / SESSION 19 / ANALOG TECHNIQUES / 19.8 Tsz Yin Man, Philip K.T. Mok and Mansun Chan [2] Texas instrument: understanding boost power stage in switchmode power supply application report, march 1999, SLVA061

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