High Speed Fully Integrated On-Chip DC/DC Power ConverterSlide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Block DiagramBuck ConverterSlide 13Slide 14Slide 15Simulation Results Cadence SpectreSimulation ResultsSlide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31Slide 32Slide 33Slide 34High Speed Fully Integrated On-Chip DC/DC Power ConverterByPrabal [email protected]: National Aeronautics and Space Administration (NASA) AdvisorDr. Herbert HessMicroelectronics Research and Communications Institute (MRCI)University of IdahoFebruary 8, 2007OutlineOutlineOverviewDesign of the High Speed DC/DC Power ConverterSimulation ResultsLayout Measured ResultsPlanned Future WorkConclusionOverviewLast 15 years has seen a significant reduction in size of portable electronics devicesOverviewPortable system is a collection of various sub-systemsSub-systems may demand multiple input voltages and variable currentsOverviewOn-chip fully integrated DC/DC power converters that provides point of use power conversion can be a possible solutionOverviewAll switch-mode power converters use inductorIn the past, most DC/DC power converter were operated at low frequency and with discrete off chip inductorQuality factor (Q) of an inductor is the function of frequency higher Q can be achieved at high frequencyRLQfQOverviewBenefits with high frequency switchingIntegrated solution for the power converterReduced passive size Higher Q inductor availableOverviewChallenges with high frequency design Parasitic capacitancePower dissipationNoiseAttenuationDesign of the High Speed DC/DC Power Converter10Sub-ComponentsSub-components used in the power converter are •A Buck Converter•Two Comparators•A Voltage Control Oscillator (VCO) •A Charge Pump11Block Diagram1.5V<1.5V01Vt3.3V0V12Buck Converter13ComparatorAmplification stageDecision making Stage Buffer stage14Ring VCO15Charge Pump – Cadence View16Simulation Results Cadence Spectre17Simulation Results Output Voltage waveform has two kinds of output ripples•High frequency ripple due to switching at 1 GHz•Low frequency ripple due to control loop at 26 MHz Output Voltage = 1.5 V18Simulation Results •High frequency ripple is 19 mV•Low frequency ripple is 65mV Output waveform19Simulation Results Vout with variable load • Vout changes with a change in the loading condition, but it takes less than 48 ns for the control loop to restore the output to the required voltage level20Simulation Results •Comparator produces logic 1 and 0 depending upon the output of the buck converterComparator Out21Simulation Results • Logic 1 or 0 from the comparator controls the operation of charge pump.•Logic 1 charges the capacitor•Logic 0 discharges the capacitorCharge Pump Out22Simulation Results VCO Out •VCO produces a near triangular wave of 1.02 GHz RCteVDDV *23Simulation Results PWM•Duty-cycle of the PULSE driving the buck converter switch is altered based upon the near DC charge pump output voltage•Basic operation is to shift the DC level of the VCO signal to change the Duty-cycle of the PULSE24Simulation Results Iout• Buck converter can supply upto 20mA of peak current.25Simulation Results Vo=1.1 VVo=1.5 VVo=1.4 VVo=1.3 VVo=1.8 V• Power converter has output range of 1.0 V to 1.8 V, but limited to loading conditions•Peak current of 20mA can be drawn only in the range of 1.0 V to 1.8 V•Output voltage range is limited by duty-cycle and comparator26Simulation Results PULSE with variable duty cycles • Control loop created different duty cycles to adjust converter outputVo=1.1 VVo=1.5 VVo=1.3 VVo=1.8 V27Power Converter Layout28Layout NMOS Closeloop – Cadence ViewCAPACITORBANKINDUCTORCONTROL CIRCUIT• Size 1180u x 900u Picture of a Fabricated Chip - NMOS29Layout PMOS Closeloop– Cadence View• Size 1180u x 900u Picture of a Fabricated Chip - PMOS30Measured Results – PreliminaryOutput voltage Max Current drawn 1.0 V 20 mA1.2 V 20 mA1.5V 20 mA1.8 V 20 mA2.0 V 19 mA 2.2 V 17 mA31Planned Future WorkIncrease the switching frequency to achieve higher Q for inductor smaller passivesIncrease efficiency Eliminate low frequency rippleUse the concept over to manufacture power converters in the industrial basis32Planned Future Work – Control Ripple33ConclusionFully integrated DC/DC converter realized in siliconThe converter takes 3.3V supply and can successfully realize voltage from 1.0 V to 1.8 V while supplying up to 20 mA of current Diameter of the power converter is 1180u x 900u34Thank You!Thank You!AcknowledgementsI would like to express my deep gratitude to Mr. Parag Upadhyaya, Washington State UniversityDr. Deukhyoun Heo, Washington State UniversityAnd MRCI team For technical discussion and supportAcknowledgementsI would like to express my deep gratitude to Mr. Parag Upadhyaya, Washington State UniversityDr. Deukhyoun Heo, Washington State UniversityAnd MRCI team For technical discussion and supportUniversity of IdahoUniversity of IdahoFebruary 8, 2007February 8, 2007High Speed Fully Integrated On-Chip DC/DC Power