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A Two-Module Linear Regulator with 3.9–10 V Input, 2.5 V Output, and 500 Ma Load

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A Two-Module Linear Regulator with 3.9–10 V Input, 2.5 V Output, and 500 Ma Load electronics Article A Two-Module Linear Regulator with 3.9–10 V Input, 2.5 V Output, and 500 mA Load Quanzhen Duan 1, Weidong Li 1, Shengming Huang 1,*, Yuemin Ding 2,*, Zhen Meng 3 and Kai Shi 2 1 School of Electrical and Electronic Engineering and Tianjin Key Laboratory of Film Electronic and Communication Devices, Tianjin University of Technology, Tianjin 300384, China; [email protected] (Q.D.); [email protected] (W.L.) 2 School of Computer and Science Engineering, Tianjin University of Technology, Tianjin 300384, China; [email protected] 3 Institute of Microelectronics of the Chinese Academy of Sciences, Beijing 100029, China; [email protected] * Correspondence: [email protected] (S.H.); [email protected] (Y.D.) Received: 7 September 2019; Accepted: 4 October 2019; Published: 10 October 2019 Abstract: A linear regulator with an input range of 3.9–10 V, 2.5 V output, and a maximal 500 mA load for use with battery systems was developed and presented here. The linear regulator featured two modules of a preregulator and a linear regulator core circuit, offering minimized power dissipation and high-level stability. The preregulator delivered an internal power voltage of 3 V and supplied internal circuits including the second module (the linear regulator core). The preregulator fitted with an active, low-pass filter provided a low-noise reference voltage to the linear regulator core circuit. To ensure operational stability for the linear regulator, error amplifiers incorporating the Miller compensation technique and featuring a large slewing rate were employed in the two modules. The circuit was successfully implemented in a 0.25 µm, 5 V complementary metal-oxide semiconductor (CMOS) process featuring 20 V drain-extended MOS (DMOS)/bipolar high-voltage devices. The total silicon area, including all pads, was approximately 1.67 mm2. To reduce chip area, bipolar rather than DMOS transistors served as the power transistors. Measured results demonstrated that the designed linear regulator was able to operate at an input voltage ranging from 3.9 to 10 V and offer a maximum 500 mA load current with fixed 2.5 V output voltage. Keywords: linear regulator; low noise; wide input range; high voltage (HV); high stability; large current load; bandgap; protection circuits 1. Introduction Today, high-voltage (HV) battery-powered systems with wide input ranges play major roles in energy storage for portable/palm notebook computers, battery chargers, wireless communication equipment, and so on [1,2]. To ensure safety, long life, and reliable operation of lithium ion batteries, an integrated circuit (IC) is generally required to manage their charging and discharging process. An IC must feature a power management circuit converting a high input voltage to a stable low voltage that supplies other IC circuits. A power management circuit featuring a cascaded DC–DC converter and low-dropout regulator (LDO) with a high system power efficiency is typically termed as a voltage regulator; however, a DC–DC converter may create large voltage ripples and, thus, reduce output voltage accuracy [3,4]. Also, the design complexity of a DC–DC converter is much higher than that of a linear regulator. The use of a linear regulator for power management affords design simplicity, less silicon area, low cost, and no ripple [5–12]. Electronics 2019, 8, 1143; doi:10.3390/electronics8101143 www.mdpi.com/journal/electronics Electronics 20192019,, 88,, 1143x FOR PEER REVIEW 22 of of 14 Consequently, an HV linear regulator for power management implemented by an HV-LDO aloneConsequently,, even with a anlower HV power linear regulatorefficiency for, becomes power managementattractive for implemented constructing bypower an HV-LDO management alone, evencircuits with used a lower in high power-accuracy efficiency, output becomes battery attractive-powered for systems. constructing Generally, power HV management-LDO composed circuits of usedhigh- involtage high-accuracy DMOS or output bipolar battery-powered transistors (BJTs) systems. only Generally,has a significantly HV-LDO high composed power of consumption high-voltage DMOSand large or bipolarsilicon transistorsarea [13–15]. (BJTs) Additionally, only has a significantlythe linear regulator high power applied consumption in HV battery and large-powered silicon areasystems [13– 15must]. Additionally, be capable of the bearing linear regulatora high current applied load in HVin a battery-powered wide input voltage systems range. must Although be capable the ofHV bearing-LDOs presented a high current in [13 load–15] are in aable wide to inputoperate voltage in a wide range. input Although voltage range, the HV-LDOs they cannot presented afford ina high [13– 15current] are able load. to operate in a wide input voltage range, they cannot afford a high current load. Therefore, we we designed designed a anovel, novel, two two-module-module HV HV-linear-linear regulator regulator based based on CMOS, on CMOS, DMOS DMOS,, and andbipolar bipolar transistors,transistors, which which was able was to able operate to operate in a wide in ainput wide voltage input voltagerange (3.9 range–10 V) (3.9–10 and achieved V) and achieveda high load a highcurrent load (500 current mA) with (500 ensured mA) with stability ensured under stability various under conditions. various The conditions. paper is Theorganized paper isas organizedfollows: Section as follows: 2 introduces Section2 theintroduces configuration the configuration of our HV oflinear our HVregulator linear regulatorcircuit, Section circuit, 3 Sectiondescribes3 describes the implementation the implementation thereof, Section thereof, 4 Section demonstrates4 demonstrates the test results the test, and results, Section and Section5 contains5 containsconclusions. conclusions. 2. Configuration Configuration of the ProposedProposed HVHV LinearLinear RegulatorRegulator CircuitCircuit FigureFigure1 1 shows shows thethe configurationconfiguration ofof thethe proposedproposed HVHV linearlinear regulator,regulator, consistingconsisting ofof aa bandgapbandgap reference, an over over-temperature-temperature protection protection (OTP) (OTP) circuit, circuit, an an over over-current-current protection protection (OCP) (OCP) circuit, circuit, a apreregulator, preregulator, and and a alinear linear regulator regulator core core circuit circuit.. The The preregulator preregulator and and linear linear regulator regulator core constitute two distinctdistinct modules.modules. TheThe preregulator preregulator converts converts a a high high input input voltage voltage to ato stable a stable low low voltage voltage (Vdd (Vdd= 3 = V 3) usedV) used for for supplying supplying most most other other circuits, circuits, as as shown shown in in Figure Figure1. 1. High-voltage High-voltage DMOS DMOS transistors transistors werewere usedused as the power transistor in the preregulator and wherever high voltage existed in the circuit design. All other devices employed were either normal CMOS transistors,transistors, for the purposes of easier control, better matching matching,, and and lower lower quiescent quiescent current current,, or or bipo bipolarlar transistors transistors in the in the output output stage stage of the of thelinear linear regulator regulator for supporting for supporting high high voltage voltage and delivering and delivering a higher a higher power power with witha smaller a smaller chip area. chip area.A high A-precision high-precision bandgap bandgap reference reference was used was to used provide to provide reference reference voltage voltage for the forpreregulator the preregulator circuit circuit[16,17]. [ 16The,17 OTP]. The and OTP OCP and circuits OCP circuits can be canused be to used safeguard to safeguard regulator regulator operation operation [18]. At [18 an]. Atinput an inputvoltage voltage ranging ranging from from3.9 to 3.9 10 to V, 10 the V, thedesign design adopted adopted a 0. a 0.25 25µmµm 5 5V VCMOS CMOS process process combined combined with 20 V DMOSDMOS/bipolar/bipolar devices to implement the circuit. To avoid interference between the preregulator and thethe corecore linearlinear regulator, regulator, the the preregulator preregulator featured featured an activean active low-pass low-pass filter filter to provide to provide a low-noise, a low- high-precisionnoise, high-precision reference reference voltage voltage (Vref 1) ( toVref the1) linearto the regulatorlinear regulator core, as core, shown as inshown Figure in1 Fig. Theure typical 1. The outputtypical voltageoutput voltage of the proposed of the proposed HV linear HV regulator linear regulator was 2.5 was V. 2.5 V. Vin Resistor Vdd Resistor Bandgap Vref Pre- network network reference Vref1 Linear Vout regulator regulator core Votp OCP OTP Vocp Figure 1. The configuration configuration of the proposed design. 3. Implementation of the P Proposedroposed HV Linear RegulatorRegulator 3.1. The Preregulator Featuring an Active Low-Pass Filter 3.1. The Preregulator Featuring an Active Low-Pass Filter Figure2 shows the preregulator consisting of an error amplifier, a start-up circuit, a resistor Figure 2 shows the preregulator consisting of an error amplifier, a start-up circuit, a resistor network circuit, and the active, low-pass filter. The start-up and resistor network circuits that operate at network circuit, and the active, low-pass filter. The start-up and resistor network circuits that operate high input voltages were implemented by DMOS transistors (DM1–DM5). The start-up circuit ensured at high input
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