A 4-μa quiescent-current dual-mode digitally controlled buck converter IC for cellular phone applications
Jinwen Xiao; Peterchev, A.V.; Jianhui Zhang; Sanders, S.R.
Solid-State Circuits, IEEE Journal of
Volume 39, Issue 12, Dec. 2004 Page(s): 2342 - 2348
Digital Object Identifier 10.1109/JSSC.2004.836353
Summary:This paper describes a dual-mode digitally controlled buck converter IC for cellular phone applications. An architecture employing internal power management is introduced to ensure voltage compatibility between a single-cell lithium-ion battery voltage and a low-voltage integrated circuit technology. Special purpose analog and digital interface elements are developed. These include a ring-oscillator-based A/D converter (ring-ADC), which is nearly entirely synthesizable, is robust against switching noise, and has flexible resolution control, and a very low power ring-oscillator-multiplexer-based digital pulse-width modulation (PWM) generation module (ring-MUX DPWM). The chip, which includes an output power stage rated for 400 mA, occupies an active area 2 mm2 in 0.25-μm CMOS. Very high efficiencies are achieved over a load range of 0.1-400 mA. Measured quiescent current in PFM mode is 4 μA.
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