An Energy Efficient <tex> $V_{\rm PP}$</tex> Generator With Fast Ramp-Up Time for Mobile DRAM

다국어 초록 (Multilingual Abstract)

<P>An energy efficient <I>V</I><SUB>PP</SUB> generator with fast ramp-up time for mobile DRAM is presented in this paper. Instead of using a fixed pumping clock frequency as in the conventional <I>V</I><SUB>PP</SUB> generator, the proposed <I>V</I><SUB>PP</SUB> generator adopts a voltage-controlled oscillator (VCO) and uses variable pumping frequencies to improve the ramp-up time as well as energy efficiency. Numerical results show that the VCO based <I>V</I><SUB>PP</SUB> generators achieve energy savings of up to 34% with 40% improvement on ramp-up time when compared to the conventional ring oscillator (RO) based design. Our proposed <I>V</I><SUB>PP</SUB> generator, which uses a three-stage voltage doubler as a charge pump, was implemented and fabricated in CMOS 0.13 μm process. The <I>V</I><SUB>PP</SUB> generator chip's core occupies 0.6 mm<SUP>2</SUP> area and consumes 1162 nJ (average power of 47.8 mW during 24 μs ramp-up time) while generating 3.0 V output voltage with 1.0 nF load capacitor, 2.0 mA current load and 1.2 V supply voltage.</P>