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A high performance adaptive on-time controlled valley-current-mode DC–DC buck converter

Chanrong Jiang, Changchun Chai, Chenxi Han and Yintang Yang

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 Corresponding author: Chanrong Jiang, crjiangxd@163.com

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Abstract: This paper presents an AOT-controlled (adaptive-on-time, AOT) valley-current-mode buck converter for portable application. The buck converter with synchronous rectifier not only uses valley-current-mode control but also possesses hybrid-mode control functions at the same time. Due to the presence of the zero-current detection circuit, the converter can switch freely between the two operating modes without the need for an external mode selection circuit, which further reduces the design difficulty and chip area. The converter for the application of high power efficiency and wide current range is used to generate the voltage of 0.6–3.0 V with a battery source of 3.3–5.0 V, while the load current range is 0.05–2 A. The circuit can work in continuous conduction mode with constant frequency in high load current range. In addition, a stable output voltage can be obtained with small voltage ripple. In pace with the load current decreases to a critical value, the converter transforms into the discontinuous conduction mode smoothly. As the switching period increases, the switching loss decreases, which can significantly improve the conversion efficiency. The proposed AOT controlled valley current mode buck converter is integrated with standard 0.18 μm process and the simulation results show that the converter provides well-loaded regulations with power efficiency over 95%. When the circuit switches between the two conduction modes drastically, the response time can be controlled within 30 μs. The undershoot voltage is controlled within 25 mV under a large current hopping range.

Key words: adaptive on-timebuck converterfast responseconstant frequencyhigh efficiency



[1]
Yu J, Hwang I, Kim N. High performance CMOS integrated PWM/PFM dual-mode DC-DC buck converter. 2017 18th International Scientific Conference on Electric Power Engineering (EPE), 2017, 1
[2]
Wang L, Lin F J, Cui Q. Dual 3-phase buck converter for multi-core CPUs power supply in mobile devices. IEICE Electron Express, 2017, 14, 20170045 doi: 10.1587/elex.14.20170045
[3]
Ma Y, Wang S, Zhang S, et al. A current mode buck/boost DC–DC converter with automatic mode transition and light load efficiency enhancement. IEICE Trans Electron, 2015, E98C, 496 doi: 10.1587/transele.E98.C.496
[4]
Chen J J, Shen J H, Hwang Y S. High-efficiency fast-transient-response V2-controlled boost converter with small ESR capacitor. Electron Lett, 2013, 49(22), 1402 doi: 10.1049/el.2013.2772
[5]
Ke X, Sankman J, Ma D. AO2T current mode buck converter with one-cycle transient response and sensorless current detection for medical meters. IEEE Applied Power Electronics Conference and Exposition (APEC), 2016
[6]
Chen X, Zhou G, Zhang K, et al. Improved constant on-time controlled buck converter with high output-regulation accuracy. Electron Lett, 2015, 51(4), 359 doi: 10.1049/el.2014.4261
[7]
Yan Y, Lee F C, Mattavelli P, et al. I2 average current mode control for switching converters. 2013 IEEE Applied Power Electronics Conference and Exposition - APEC, 2013
[8]
Chen J J, Hwang Y S, Chen J H, et al. A new fast-response current-mode buck converter with improved I2-controlled techniques. IEEE Trans Very Large Scale Integr (VLSI) Syst, 2018, 26, 903 doi: 10.1109/TVLSI.2018.2796088
[9]
Redl R, Sun J. Ripple-based control of switching regulators-an overview. IEEE Trans Power Electron, 2010, 24(12), 2669 doi: Ripple-basedcontrolofswitchingregulators-anoverview
[10]
Lee C F, Mok P K T. A monolithic current-mode CMOS DC-DC converter with on-chip current-sensing technique. IEEE J Solid-State Circuits, 2004, 39(1), 3 doi: 10.1109/JSSC.2003.822927
[11]
Sahu B, Rincn-Mora G A. An accurate, low-voltage, CMOS switching power supply with adaptive on-time pulse-frequency modulation (PFM) control. IEEE Trans Circuits Syst I, 2007, 54(2), 312 doi: 10.1109/TCSI.2006.887472
[12]
Nam H, Ahn Y, Roh J. A buck converter with adaptive on-time PFM control and adjustable output voltage. Analog Integr Circuits Signal Process, 2012, 71(2), 327 doi: 10.1007/s10470-011-9802-7
[13]
Qiu Y, Liu H, Chen X. Digital average current-mode control of PWM DC–DC converters without current sensors. IEEE Trans Ind Electron, 2010, 57(5), 1670 doi: 10.1109/TIE.2009.2032130
[14]
Barrado A, Vazquez R, Lazaro A, et al. Fast transient response with combined linear-non-linear control applied to buck converters. IEEE Power Electronics Specialists Conference, 2002
[15]
Lee M C, Jing X, Mok P K T. A 14V-output adaptive-off-time boost converter with quasi-fixed-frequency in full loading range. IEEE International Symposium of Circuits and Systems (ISCAS), 2011
[16]
Jing X, Mok P K T, Lee M C. Current-slope-controlled adaptive-on-time DC-DC converter with fixed frequency and fast transient response. IEEE International Symposium on Circuits & Systems, 2011
[17]
Xu Y, Xu J, Xu L, et al. Constant frequency turn-on time control dynamic voltage scaling boost converter. International Conference on Communications, 2013
[18]
Jing X, Mok P K T. A fast fixed-frequency adaptive-on-time boost converter with light load efficiency enhancement and predictable noise spectrum. IEEE J Solid-State Circuits, 2013, 48(10), 2442 doi: 10.1109/JSSC.2013.2269852
[19]
Li Q, Lai X, Zhong L. Adaptive current-threshold detector for an adaptive on-time buck converter at light load. Analog Integr Circuits Signal Process, 2018, 95, 541 doi: 10.1007/s10470-018-1140-6
[20]
Li J, Lee F C. New modeling approach and equivalent circuit representation for current-mode control. IEEE Trans Power Electron, 2010, 25(5), 1218 doi: 10.1109/TPEL.2010.2040123
[21]
Shi H, Sun Z, Xu Y, et al. Design of the 1.0 V bandgap reference on chip. IEEE International Conference on ASIC, 2016
[22]
Huang S P, Feng Q Y, University S J. Design of a novel zero-cross detection circuit for synchronous buck converter. Chin J Electron Devices, 2014, 37, 408 doi: :10.3969/j.issn.1005-9490.2014.03.007
[23]
Yuan B, Lai X Q, Wang H Y, et al. High-efficient hybrid buck converter with switch-on-demand modulation and switch size control for wide-load low-ripple applications. IEEE Trans Microwave Theory Tech, 2013, 61(9), 3329 doi: 10.1109/TMTT.2013.2271757
[24]
Jin Y Y, Xu J P, Zhou G H. Constant on-time digital peak voltage control for buck converter. Energy Conversion Congress & Exposition, 2010, 2030 doi: 10.1109/ECCE.2010.5618100
[25]
Gildersleeve M, Forghanizadeh H P, Member S, et al. A comprehensive power analysis and a highly efficient, mode-hopping DC–DC converter. IEEE Asia-pacific Conference on ASIC, 2002
[26]
Huang C, Mok P K T. A 100 MHz 82.4% efficiency package-bondwire based four-phase fully-integrated buck converter with flying capacitor for area reduction. IEEE J Solid-State Circuits, 2013, 48(12), 2977 doi: 10.1109/JSSC.2013.2286545
[27]
Li P, Xue L, Hazucha P, et al. A delay-locked loop synchronization scheme for high-frequency multiphase hysteretic DC–DC converters. IEEE J Solid-State Circuits, 2009, 44(11), 3131 doi: 10.1109/JSSC.2009.2033508
[28]
Lee B, Song M K, Maity A, et al. 10.7 A 25 MHz 4-phase SAW hysteretic DC–DC converter with 1-cycle APC achieving 190 ns tsettle to 4 A load transient and above 80% efficiency in 96.7% of the power range. Solid-State Circuits Conference, 2017
[29]
Teh C K, Suzuki A, Yamada M, et al. 4.1 A 3-phase digitally controlled DC-DC converter with 88% ripple reduced 1-cycle phase adding/dropping scheme and 28% power saving CT/DT hybrid current control. IEEE International Solid-State Circuits Conference Digest of Technical Papers, 2014
Fig. 1.  Schematic of the AOT controlled buck converter.

Fig. 2.  The adaptive on-time controller.

Fig. 3.  Bode plot of closed loop after compensation.

Fig. 4.  Structure diagram of the zero crossing detection module.

Fig. 5.  The threshold voltage comparator.

Fig. 6.  (Color online) Simulation results of constant frequency. (a) Varying load current. (b) Varying input voltage. (c) Varying output voltage.

Fig. 7.  (Color online) The relationship of Ts between traditional COT and AOT structure proposed in this paper. (a) Variable input voltage. (b) Variable output voltage.

Fig. 8.  (Color online) Simulated load transient response (Vo: 1.2 V, IL: 0.4 →1.2→0.4 A).

Fig. 9.  (Color online) Output variation curve caused by load current variation.

Fig. 10.  (Color online) Conversion efficiency versus load current at different output voltages.

Table 1.   Comparison results of transient performance between COT, PWM and AOT.

Control techniqueInput voltage (V)Output voltage (V)Normalized voltage dropNormalized voltage overshootNormalized setting cycle
Load step variation from 1 to 2 A
COT-DPV151.50.7800.81
PWM-DPV51.510.361
AOT51.50.5800.25
Load step variation from 2 to 1 A
COT-DPV51.501.530.826
PWM-DPV51.50.4311
AOT51.500.560.188
1DPV: digital peak voltage
DownLoad: CSV

Table 2.   Comparison results of different control methods.

Control techniquePWM/PFM[1]PWM[26]DLL[27]SAW[28]CTDT[29]This work
ResultSimulationMeasureMeasureMeasureMeasureSimulation
Process (μm)0.35 0.130.50.350.25 0.18
Vin (V)3.3–51.24.83.355
Vo (V)0.5–3.00.6–1.053.30.3–2.51.51.8
Peak efficiency (%)9082.48388.190.295.5
Inductor (μH)500–3000 0.003–0.008 0.11–0.220.22 2.21.5
Output capacitor (μF)50–200 0.003730.008–0.192.5 6 20
fsw (MHz)0.5–2.1100~30250.51
DownLoad: CSV

Table 3.   Performance summary.

ParameterValue
ProcessStandard 0.18 μm process
Supply voltage3.3–5.0 V
Output voltage0.6–3.0 V
Switching frequency1 MHz
Load current50–2000 mA
Inductor1.5 μH
Output capacitor/ESR20 μF/1 mΩ
Maximum Efficiency95.5%
Load regulation rate0.19%/A
DownLoad: CSV
[1]
Yu J, Hwang I, Kim N. High performance CMOS integrated PWM/PFM dual-mode DC-DC buck converter. 2017 18th International Scientific Conference on Electric Power Engineering (EPE), 2017, 1
[2]
Wang L, Lin F J, Cui Q. Dual 3-phase buck converter for multi-core CPUs power supply in mobile devices. IEICE Electron Express, 2017, 14, 20170045 doi: 10.1587/elex.14.20170045
[3]
Ma Y, Wang S, Zhang S, et al. A current mode buck/boost DC–DC converter with automatic mode transition and light load efficiency enhancement. IEICE Trans Electron, 2015, E98C, 496 doi: 10.1587/transele.E98.C.496
[4]
Chen J J, Shen J H, Hwang Y S. High-efficiency fast-transient-response V2-controlled boost converter with small ESR capacitor. Electron Lett, 2013, 49(22), 1402 doi: 10.1049/el.2013.2772
[5]
Ke X, Sankman J, Ma D. AO2T current mode buck converter with one-cycle transient response and sensorless current detection for medical meters. IEEE Applied Power Electronics Conference and Exposition (APEC), 2016
[6]
Chen X, Zhou G, Zhang K, et al. Improved constant on-time controlled buck converter with high output-regulation accuracy. Electron Lett, 2015, 51(4), 359 doi: 10.1049/el.2014.4261
[7]
Yan Y, Lee F C, Mattavelli P, et al. I2 average current mode control for switching converters. 2013 IEEE Applied Power Electronics Conference and Exposition - APEC, 2013
[8]
Chen J J, Hwang Y S, Chen J H, et al. A new fast-response current-mode buck converter with improved I2-controlled techniques. IEEE Trans Very Large Scale Integr (VLSI) Syst, 2018, 26, 903 doi: 10.1109/TVLSI.2018.2796088
[9]
Redl R, Sun J. Ripple-based control of switching regulators-an overview. IEEE Trans Power Electron, 2010, 24(12), 2669 doi: Ripple-basedcontrolofswitchingregulators-anoverview
[10]
Lee C F, Mok P K T. A monolithic current-mode CMOS DC-DC converter with on-chip current-sensing technique. IEEE J Solid-State Circuits, 2004, 39(1), 3 doi: 10.1109/JSSC.2003.822927
[11]
Sahu B, Rincn-Mora G A. An accurate, low-voltage, CMOS switching power supply with adaptive on-time pulse-frequency modulation (PFM) control. IEEE Trans Circuits Syst I, 2007, 54(2), 312 doi: 10.1109/TCSI.2006.887472
[12]
Nam H, Ahn Y, Roh J. A buck converter with adaptive on-time PFM control and adjustable output voltage. Analog Integr Circuits Signal Process, 2012, 71(2), 327 doi: 10.1007/s10470-011-9802-7
[13]
Qiu Y, Liu H, Chen X. Digital average current-mode control of PWM DC–DC converters without current sensors. IEEE Trans Ind Electron, 2010, 57(5), 1670 doi: 10.1109/TIE.2009.2032130
[14]
Barrado A, Vazquez R, Lazaro A, et al. Fast transient response with combined linear-non-linear control applied to buck converters. IEEE Power Electronics Specialists Conference, 2002
[15]
Lee M C, Jing X, Mok P K T. A 14V-output adaptive-off-time boost converter with quasi-fixed-frequency in full loading range. IEEE International Symposium of Circuits and Systems (ISCAS), 2011
[16]
Jing X, Mok P K T, Lee M C. Current-slope-controlled adaptive-on-time DC-DC converter with fixed frequency and fast transient response. IEEE International Symposium on Circuits & Systems, 2011
[17]
Xu Y, Xu J, Xu L, et al. Constant frequency turn-on time control dynamic voltage scaling boost converter. International Conference on Communications, 2013
[18]
Jing X, Mok P K T. A fast fixed-frequency adaptive-on-time boost converter with light load efficiency enhancement and predictable noise spectrum. IEEE J Solid-State Circuits, 2013, 48(10), 2442 doi: 10.1109/JSSC.2013.2269852
[19]
Li Q, Lai X, Zhong L. Adaptive current-threshold detector for an adaptive on-time buck converter at light load. Analog Integr Circuits Signal Process, 2018, 95, 541 doi: 10.1007/s10470-018-1140-6
[20]
Li J, Lee F C. New modeling approach and equivalent circuit representation for current-mode control. IEEE Trans Power Electron, 2010, 25(5), 1218 doi: 10.1109/TPEL.2010.2040123
[21]
Shi H, Sun Z, Xu Y, et al. Design of the 1.0 V bandgap reference on chip. IEEE International Conference on ASIC, 2016
[22]
Huang S P, Feng Q Y, University S J. Design of a novel zero-cross detection circuit for synchronous buck converter. Chin J Electron Devices, 2014, 37, 408 doi: :10.3969/j.issn.1005-9490.2014.03.007
[23]
Yuan B, Lai X Q, Wang H Y, et al. High-efficient hybrid buck converter with switch-on-demand modulation and switch size control for wide-load low-ripple applications. IEEE Trans Microwave Theory Tech, 2013, 61(9), 3329 doi: 10.1109/TMTT.2013.2271757
[24]
Jin Y Y, Xu J P, Zhou G H. Constant on-time digital peak voltage control for buck converter. Energy Conversion Congress & Exposition, 2010, 2030 doi: 10.1109/ECCE.2010.5618100
[25]
Gildersleeve M, Forghanizadeh H P, Member S, et al. A comprehensive power analysis and a highly efficient, mode-hopping DC–DC converter. IEEE Asia-pacific Conference on ASIC, 2002
[26]
Huang C, Mok P K T. A 100 MHz 82.4% efficiency package-bondwire based four-phase fully-integrated buck converter with flying capacitor for area reduction. IEEE J Solid-State Circuits, 2013, 48(12), 2977 doi: 10.1109/JSSC.2013.2286545
[27]
Li P, Xue L, Hazucha P, et al. A delay-locked loop synchronization scheme for high-frequency multiphase hysteretic DC–DC converters. IEEE J Solid-State Circuits, 2009, 44(11), 3131 doi: 10.1109/JSSC.2009.2033508
[28]
Lee B, Song M K, Maity A, et al. 10.7 A 25 MHz 4-phase SAW hysteretic DC–DC converter with 1-cycle APC achieving 190 ns tsettle to 4 A load transient and above 80% efficiency in 96.7% of the power range. Solid-State Circuits Conference, 2017
[29]
Teh C K, Suzuki A, Yamada M, et al. 4.1 A 3-phase digitally controlled DC-DC converter with 88% ripple reduced 1-cycle phase adding/dropping scheme and 28% power saving CT/DT hybrid current control. IEEE International Solid-State Circuits Conference Digest of Technical Papers, 2014
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    Received: 13 August 2019 Revised: 21 December 2019 Online: Accepted Manuscript: 18 February 2020Uncorrected proof: 21 February 2020Published: 01 June 2020

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      Chanrong Jiang, Changchun Chai, Chenxi Han, Yintang Yang. A high performance adaptive on-time controlled valley-current-mode DC–DC buck converter[J]. Journal of Semiconductors, 2020, 41(6): 062402. doi: 10.1088/1674-4926/41/6/062402 C R Jiang, C C Chai, C X Han, Y T Yang, A high performance adaptive on-time controlled valley-current-mode DC–DC buck converter[J]. J. Semicond., 2020, 41(6): 062402. doi: 10.1088/1674-4926/41/6/062402.Export: BibTex EndNote
      Citation:
      Chanrong Jiang, Changchun Chai, Chenxi Han, Yintang Yang. A high performance adaptive on-time controlled valley-current-mode DC–DC buck converter[J]. Journal of Semiconductors, 2020, 41(6): 062402. doi: 10.1088/1674-4926/41/6/062402

      C R Jiang, C C Chai, C X Han, Y T Yang, A high performance adaptive on-time controlled valley-current-mode DC–DC buck converter[J]. J. Semicond., 2020, 41(6): 062402. doi: 10.1088/1674-4926/41/6/062402.
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      A high performance adaptive on-time controlled valley-current-mode DC–DC buck converter

      doi: 10.1088/1674-4926/41/6/062402
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      • Corresponding author: crjiangxd@163.com
      • Received Date: 2019-08-13
      • Revised Date: 2019-12-21
      • Published Date: 2020-06-01

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