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Low-Dropout Regulator with modest ripple and rugged performance in 180nm

Low-Dropout Regulator with modest ripple and rugged performance in 180nm. Presentation Outline. INTRODUCTION LINEAR REGULATOR CONCEPTS CIRCUIT IMPLEMENTATION PERFORMANCE ANALYSIS CONCLUSION. INTRODUCTION.

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Low-Dropout Regulator with modest ripple and rugged performance in 180nm

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  1. Low-Dropout Regulator with modest ripple and rugged performance in 180nm

  2. Presentation Outline INTRODUCTION LINEAR REGULATOR CONCEPTS CIRCUIT IMPLEMENTATION PERFORMANCE ANALYSIS CONCLUSION

  3. INTRODUCTION Supplying and conditioning power are the most fundamental functions of an electrical system. A loading application cannot sustain itself without energy, and cannot fully perform its functions without a stable supply Transformers, generators, batteries, and other off-line supplies incur substantial voltage and current variations across time and over a wide range of operating conditions High frequency switching circuits CPU and DSP circuits utilized in an application usually load it. Solution for above mentioned problems is to use a power converter Low-Dropout Regulator with modest ripple and rugged performance in 180nm 1

  4. LINEAR REGULATOR CONCEPT OF LINEAR REGULATOR to sense and generate a correcting signal (high voltage gain) pass device to mediate and conduct whatever load current is required from the unregulated input supply to the regulated output stable dc-bias voltage impervious to noise, temperature, and input-supply voltage variations to sense the output reacts to offset and cancel effects of load current, input voltage, temperature, and an array of other variations on the output 2 Low-Dropout Regulator with modest ripple and rugged performance in 180nm

  5. LINEAR REGULATOR Transient response of LDO • LDO provide power to low-voltage digital circuits operating under different modes of operation --voltage transients-cannot be handled by digital circuits • Factors affecting transient response of an LDO • The internal compensation of the LDO • The amount of output capacitance • The parasitics of the output capacitor • The faster local feedback n/w responds quicker to load changes than more complicated regulator loop • The additional loop has negligible effects on dc accuracy as its low frequency gain is kept well below that of the regulator • The additional loop also demand little to no current to have less impact on operational life of battery Low-Dropout Regulator with modest ripple and rugged performance in 180nm 3

  6. LINEAR REGULATOR REGULATING PERFORMANCE LOAD REGULATION • Steady-state (dc) voltage variations in the output (ΔVOUT) resulting from dc changes in load current (ΔILOAD) define load regulation(LDR) performance • Systematic input-offset voltages, which result from asymmetric currents and volt-ages in the feedback error amplifier, further degrade load-regulation performance • Even if the LDO were symmetric, its widely variable load would cause considerable voltage swings at internal nodes, subjecting some of the devices to asymmetric conditions • LINE REGULATION • Line regulation(LNR) performance is a dc parameter and it refers to output voltage variations arising from dc changes in the input supply • Power-supply variations affect the regulator in two ways • Directly through its own supply • Indirectly via supply-induced variations in reference VREF Low-Dropout Regulator with modest ripple and rugged performance in 180nm 4

  7. LINEAR REGULATOR PROCESS AND TEMPERATURE INDEPENDENT BIASING • The transconductance of MOSFETs determine performance parameters: small signal gain, speed and noise. • It is desirable to bias the transistors such that their transconductance is independent of process, supply voltage and temperature Low-Dropout Regulator with modest ripple and rugged performance in 180nm 5

  8. LINEAR REGULATOR Circuit Implementation PASS TRANSISTOR FEED BACK NETWORK PROCESS AND TEMPERATURE INDEPENDENT BIASING FEEDBACK NETWORK ERROR AMPLIFIER ERROR AMPLIFIER FAST REACTING PATHS FAST REACTING PATHS Low-Dropout Regulator with modest ripple and rugged performance in 180nm 6

  9. Linear Regulator FIRST FAST REACTING PATH FIRST REACTING PATH Low-Dropout Regulator with modest ripple and rugged performance in 180nm 7

  10. Linear Regulator SECOND FAST REACTING PATH FIRST REACTING PATH When load current output voltage The loop results in of Vgs of Mf4 which is coupled through cm2 to input of M18 Its operation current leads to in drive for Mp restoring output voltage to its original value Low-Dropout Regulator with modest ripple and rugged performance in 180nm 8

  11. Linear Regulator THIRD FAST REACTING PATH FIRST REACTING PATH Transistors Mf6-Mf9, Mp, and feedback resistors R1-R2 form the third self-reacting path Transistors Mf6-Mf9 constitute an error amplifier When load current the output voltage The output voltage of error amplifier leading to drive for M18 Gate voltage of Mp thus restoring the output voltage Low-Dropout Regulator with modest ripple and rugged performance in 180nm 9

  12. Linear Regulator AC ANALYSIS • The Phase Margin for this load current range is above 95O, loop-gain is about 72dB • means a stable LDO and enough gain for a high output voltage accuracy Low-Dropout Regulator with modest ripple and rugged performance in 180nm 10

  13. Linear Regulator DC ANALYSIS Low-Dropout Regulator with modest ripple and rugged performance in 180nm 11

  14. Linear Regulator TRANSIENT ANALYSIS Low-Dropout Regulator with modest ripple and rugged performance in 180nm 12

  15. Linear Regulator RIPPLE IN OUTPUT VOLTAGE • It has ripple voltage equal to 0.9 mv • means a stable LDO and • high output voltage accuracy Low-Dropout Regulator with modest ripple and rugged performance in 180nm 13

  16. Linear Regulator PSRR (POWER SUPPLY REJECTION RATIO) • It has PSRR of 42dB @1Khz • At low frequencies the PSRR is very high which results in high suppression of disturbances from the supply line. In the higher frequency area of > 1 MHz the PSRR gets very small and even reaches 0 dB at 6 MHz. This means that a 1 MHz signal would pass through the regulator without attenuation Low-Dropout Regulator with modest ripple and rugged performance in 180nm 14

  17. LINEAR REGULATORS MEASURED PERFORMANCE Summary of measured performance Low-Dropout Regulator with modest ripple and rugged performance in 180nm 15

  18. Conclusion • LDO regulator targeted for SOC applications • (optimized design for performance, board area, and cost) • LDO is stable for output current in the complete range from 0 to 100 mA • LDO with high regulation accuracy and fast transient response 16 Low-Dropout Regulator with modest ripple and rugged performance in 180nm

  19. REFERENCES [1] Sai Kit Lau, K.N. Leung, and P.K.T. Mok,“Analysis of low-dropout regulatorTopologiesfor low-voltageregulation”,inIEEE Conference of Electron Devices and Solid-StateCircuits,December2003 [2] P.Hazucha,T.Karnik,B.A Bradley,C. Parsons,D.Finan,and S.Borkar,”area –efficient linear regulator withultra fast load regulation,” IEEE J. Solid-StateCircuits, vol. 40, no. 4, pp.933-940, Apr. 2005 [3] P. Y. Or and K. N. Leung, “An output-capacitorless low-dropout regulator with direct voltage-spike detection,” IEEE J. Solid-State Circuits, vol. 45, no. 2, pp. 458-466, Feb. 2010. [4] T. Y. Man, K. N. Leung, C. Y. Leung, P. K. T. Mok, and M. Chan,“Development of single-transistor control LDO based on flipped voltage follower for SoC,” IEEE Trans.Circuits Sys. I, vol. 55, no. 5, pp. 1392-1401, Jun. 2008. [5]Texas Instruments, “Fundamental theory of PMOS low-dropout voltage regulators”,TexasInstruments Inc., SLVA068, Dallas, TX, USA, April 1999. [6]Chester Simpson, “Linear and switching voltage regulator fundamentals”, NationalSemiconductor Corporation, Santa Clara, CA, USA, 1995. [7] Chia-Min Chen,Chung-Chih Hung, “A Fast Self-Reacting Capacitor-less Low-Dropout Regulator, ” IEEE Trans. Circuits Syst. I, pp. 375-378, Sept. 2011 [8]Frederik Dostal, “How and when to use low dropout linear regulators”, Embedded ControlEurope Magazine, pp. 16-19. March 2004 Issue. [9]R. J. Milliken, J. Silva-Martinez and E. Sanchez- Sinencio, “Full onchipCMOS low-dropout voltage regulator,” IEEE Trans. Circuits Syst. I,vol. 54, no. 9, pp. 1879-1890, Sept. 2007. [10]S. K. Lau, P. K. T. Mok, and K. N. Leung, “A low-dropout regulator forSoC with Q-reduction,” IEEE J. Solid-State Circuits, vol. 42, no. 3, pp.658-664, Mar. 2007. [11] D.A.Johns, K.Martin, “Analog Integrated Circuit Design,” John Wiley and Sons Inc, U.K.,246-251(1997) Low-Dropout Regulator with modest ripple and rugged performance in 180nm 17

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