A low substrate loss, monolithically integrated power inductor for compact LED drivers

Fang, Xiangming; Mak, Tsz Him; Gao, Yuan; Lau, Kei May; Mok, Philip K. T.; Sin, J.K.O.

doi:10.1109/ispsd.2015.7123387

Cited by 10 publications

(9 citation statements)

References 9 publications

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“…For instance, Figure 1.1 depicts a typical automotive LED lighting system for a myriad of exterior lights such as the stop/tail lights, turn indicators, daytime running lights, headlights, etc. [5], [6] DC Battery (e.g., 12V) Unlike the traditional fluorescent and incandescent counterparts [7], which are voltage driven, LED lighting is current driven [8], [9]. This is evident in the LED IV characteristics depicted in Figure 1.2, where a small 8% forward voltage increase, ΔVF, leads to a large 110% LED current increase, ΔILED.…”

Section: Acknowledgementsmentioning

confidence: 99%

“…The power losses in the LED driver include the switching loss, conduction loss, gate driving loss, inductor loss, etc. [9], where the former three are dissipated in power switches (transistors). Consider now these losses.…”

Section: B Power Losses In the Led Drivermentioning

confidence: 99%

“…Once the overshoot/undershoot voltage is beyond the breakdown voltage of the power transistors, it subsequently results in failure of the power transistors [4]. It is well recognized that monolithic integration shows privileges in parasitic inductance/capacitance minimization [9].…”

Section: B Led Driver Reliabilitymentioning

confidence: 99%

“…9 shows the emulated cold-cranking transient performance of the proposed LED driver when the input voltage HVDD (i.e., VIN) rises from 16V to 7V within 50µs. It can be observed that there is no overshoot/undershoot current (and voltage), and that the output LED current remains constant.…”

mentioning

confidence: 99%

“…In the case of LED drivers, the output low-pass filter should be laid out as compactly as possible and kept close to the power stage. Hence, a monolithic integration would mitigate radiated EMI[9].Second, radiated EMI can be mitigated by the adoption of superior control methodology, where for automotive lighting applications, these would be based on either PFM or PWM. Reported PFM offers hardware and design simplicity[97].However, because of its variable switching frequency, PFM generates wide and unpredictable EMI spectrum.…”

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confidence: 99%

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Design and realization of high-performance LED drivers for automotive lighting applications

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This Ph.D. program pertains to the design and monolithic realization of Light Emitting Diode (LED) drivers for automotive lighting where the imperative parameters are high power-efficiency and high reliability. The grand objectives thereto are substantial improved specifications over the state-of-the-art, including power-efficiency, reliability, current driving capability, and dimming range. To achieve the said grand objectives, the specific objectives are to decouple, and hence mitigate the following two major design trade-offs that limit the performance of contemporary automotive LED drivers. The first trade-off is between high reliability and high current driving capability, and applies to both single-phase and multi-phase LED drivers. Specifically, to achieve high current driving capability, the contemporary single-phase LED driver typically suffers from low reliability arising from large current ripples. On the other hand, the multi-phase LED driver is highly advantageous to provide high current driving capability, but suffers from low reliability because of the ensuing subharmonic oscillation. To decouple this limiting trade-off, we propose the design and monolithic realization of a novel Pulse-Width-Modulation (PWM)-based dual-phase LED driver in Global Foundries (GF) 130nm BCDLite process. To achieve high current driving capability, we adopt a dual-phase power stage. To achieve high reliability, we propose an Average Current Control to eliminate the subharmonic oscillation by considering the complete inductor-current profile vis-à-vis peak current adopted/reported elsewhere. To further improve the reliability, we propose an accuracy-enhanced current sensor to ascertain good current balance in the adopted dual-phase power stage. With measurements on our prototype LED driver ICs embodying our aforesaid adoption and vi proposed circuits, we demonstrate, to the best of our knowledge, for the first time that the trade-off between high reliability and high current driving capability is decoupled, i.e., an LED driver uniquely featuring high reliability, yet high current driving capability. The second trade-off is between high power-efficiency and wide dimming range. Specifically, a wide dimming range is derived by means of high switching frequency, hence the ensuing reduced settling time of the LED current. This, however, in turn leads to a degradation of the power-efficiency due to increased switching losses. To decouple this limiting trade-off, we propose the design and monolithic realization of a novel fully soft-switched LED driver in GF 130nm BCDLite process. We achieve wide dimming range by operating at high switching frequencies, but the high switching does not compromise the power-efficiency. Using a fully soft-switching approach, the ensuing switching losses are negligible. This is achieved by a proposed Hysteretic Soft-Switching Controller (HSSC) and proposed circuitries, i.e., a voltage detector, current sensor, and a level shifter. The HSSC enables complete soft-switching, including zerovoltage switc...

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Section: Acknowledgementsmentioning

confidence: 99%

Section: B Power Losses In the Led Drivermentioning

confidence: 99%

Section: B Led Driver Reliabilitymentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Design and realization of high-performance LED drivers for automotive lighting applications

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Dimmable integrated CMOS LED driver based on a resonant DC/DC hybrid‐switched capacitor converter

Castellanos

Turhan

Hendrix

et al. 2018

Circuit Theory & Apps

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SummaryThis paper presents a 7.7‐mm2 on‐chip LED driver based on a DC/DC resonant hybrid‐switched capacitor converter operating in the MHz range with and without output capacitor. The converter operation allows continuously dimming the LED while keeping control on both peak and average current. Also, it features no flickering even in the absence of output capacitor and for light dimmed down to 10% of the nominal value. The capacitors and switches of the LED driver are integrated on a single IC die fabricated in a low‐cost 5 V 0.18‐μm bulk CMOS technology. This LED driver uses a small (0.7 mm2) inductor of 100 nH, which is 10 times smaller value than prior art integrated inductive LED drivers, still showing a competitive peak efficiency of 93% and achieving a power density of 0.26 W/mm2 (0.34 W/mm3).

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MEMS inductor fabrication and emerging applications in power electronics and neurotechnologies

et al. 2021

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MEMS inductors are used in a wide range of applications in micro- and nanotechnology, including RF MEMS, sensors, power electronics, and Bio-MEMS. Fabrication technologies set the boundary conditions for inductor design and their electrical and mechanical performance. This review provides a comprehensive overview of state-of-the-art MEMS technologies for inductor fabrication, presents recent advances in 3D additive fabrication technologies, and discusses the challenges and opportunities of MEMS inductors for two emerging applications, namely, integrated power electronics and neurotechnologies. Among the four top-down MEMS fabrication approaches, 3D surface micromachining and through-substrate-via (TSV) fabrication technology have been intensively studied to fabricate 3D inductors such as solenoid and toroid in-substrate TSV inductors. While 3D inductors are preferred for their high-quality factor, high power density, and low parasitic capacitance, in-substrate TSV inductors offer an additional unique advantage for 3D system integration and efficient thermal dissipation. These features make in-substrate TSV inductors promising to achieve the ultimate goal of monolithically integrated power converters. From another perspective, 3D bottom-up additive techniques such as ice lithography have great potential for fabricating inductors with geometries and specifications that are very challenging to achieve with established MEMS technologies. Finally, we discuss inspiring and emerging research opportunities for MEMS inductors.

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A low substrate loss, monolithically integrated power inductor for compact LED drivers

Cited by 10 publications

References 9 publications

Design and realization of high-performance LED drivers for automotive lighting applications

Design and realization of high-performance LED drivers for automotive lighting applications

Dimmable integrated CMOS LED driver based on a resonant DC/DC hybrid‐switched capacitor converter

MEMS inductor fabrication and emerging applications in power electronics and neurotechnologies

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