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Showing papers by "Freescale Semiconductor published in 2009"


Journal ArticleDOI
TL;DR: This paper describes the design and performance of a 90 nm CMOS SAW-less receiver with DigRF interface that supports 10 WCDMA bands and 4 GSM bands and results in current drain and die area savings as well as improved noise.
Abstract: This paper describes the design and performance of a 90 nm CMOS SAW-less receiver with DigRF interface that supports 10 WCDMA bands (I, II, III, IV, V, VI, VIII, IX, X, XI) and 4 GSM bands (GSM850, EGSM900, DCS1800, PCS1900). The receiver is part of a single-chip SAW-less transceiver reference platform IC for mass-market smartphones, which has been designed to meet Category 10 HSDPA (High Speed Downlink Packet Access) requirements. The novel receiver core consists of a single-stage transconductance amplifier (TCA) with large gain control range, a current commutating passive mixer enhanced for automatic on chip IIP2 calibration with 25% duty-cycle LO injection and threshold adjust, and current-input complex Direct Coupled Filter (DCF). The low noise TCAs are designed without inductive loads to save area. A self-contained on chip automatic IIP2 calibration system with algorithm routine, implemented in firmware, is used to optimize IIP2 performance. This topology eliminates the external LNA, inter-stage SAW filter and transimpedance amplifier (TZA) in conventional WCDMA designs and results in current drain and die area savings as well as improved noise. The 25% duty-cycle LO injection, with threshold adjustment, into a current driven passive double-balanced mixer results in 3 dB additional gain, lower noise figure and lower intermodulation distortion. Large signal blocking and 1/f noise performance are improved significantly by eliminating the 0 and 180deg LO signal crossover at the mixer. The full receiver achieves 2.2 dB/2.39 dB simplex/duplex NF (with - 24.5 dBm TX leakage), > 90 dBm complex two-tone IIP2, 60 dB gain and - 1/+ 5 dBm half/full-duplex image IIP3. The receiver core consumes only 15.1 mA from a 1.5 V supply.

210 citations


Journal ArticleDOI
TL;DR: Algorithms for resource allocation in Single Carrier Frequency Division Multiple Access (SC-FDMA) systems, which is the uplink multiple access scheme considered in the 3GPP-LTE standard, are presented and a greedy heuristic algorithm that approaches the optimal performance in cases of practical interest is presented.
Abstract: We present algorithms for resource allocation in Single Carrier Frequency Division Multiple Access (SC-FDMA) systems, which is the uplink multiple access scheme considered in the Third Generation Partnership Project-Long Term Evolution (3GPP-LTE) standard. Unlike the well-studied problem of Orthogonal Frequency Division Multiple Access (OFDMA) resource allocation, the "subchannel adjacency" restriction, whereby users can only be assigned multiple subchannels that are adjacent to each other, makes the problem much harder to solve. We present a novel reformulation of this problem as a pure binary-integer program called the set partitioning problem, which is a well studied problem in operations research. We also present a greedy heuristic algorithm that approaches the optimal performance in cases of practical interest. We present simulation results for 3GPP-LTE uplink scenarios.

203 citations


Journal ArticleDOI
TL;DR: This paper develops optimal resource allocation algorithms for the OFDMA downlink assuming the availability of only partial (imperfect) CSI, and considers both continuous and discrete ergodic weighted sum rate maximization subject to total power constraints, and average bit error rate constraints for the discrete rate case.
Abstract: Previous research efforts on OFDMA resource allocation have typically assumed the availability of perfect channel state information (CSI). Unfortunately, this is unrealistic, primarily due to channel estimation errors, and more importantly, channel feedback delay. In this paper, we develop optimal resource allocation algorithms for the OFDMA downlink assuming the availability of only partial (imperfect) CSI. We consider both continuous and discrete ergodic weighted sum rate maximization subject to total power constraints, and average bit error rate constraints for the discrete rate case. We approach these problems using a dual optimization framework, allowing us to solve these problems with O(MK) complexity per symbol for an OFDMA system with K used subcarriers and M active users, while achieving relative optimality gaps of less than 10-5 for continuous rates and less than 10-3 for discrete rates in simulations based on realistic parameters.

154 citations


Patent
22 Oct 2009
TL;DR: In this paper, an identification tag is provided in which radio frequency (RF) circuitry and ultrawide bandwidth (UWB) circuitry are both provided on the same tag, along with some UWB-RF interface circuitry.
Abstract: An identification tag is provided in which radio frequency (RF) circuitry and ultrawide bandwidth (UWB) circuitry are both provided on the same tag, along with some UWB-RF interface circuitry. The RF circuitry is used to detect when the identification tag must be accessed, and is used to connect the UWB circuitry with a power supply. The UWB circuitry then performs the necessary communication functions with a distant device and the power supply is again disconnected. In this way the power supply is only accessed when the UWB circuitry is needed and it's usable lifetime can be maximized.

98 citations


Patent
30 Oct 2009
TL;DR: In this article, a microelectromechanical system (MEMS) sensor device includes a sensor portion ( 180 ) and a sensor part ( 182 ) that are coupled together to form a vertically integrated configuration having a hermetically sealed chamber.
Abstract: A microelectromechanical systems (MEMS) sensor device ( 184 ) includes a sensor portion ( 180 ) and a sensor portion ( 182 ) that are coupled together to form a vertically integrated configuration having a hermetically sealed chamber ( 270 ) The sensor portions ( 180, 182 ) can be formed utilizing different micromachining techniques, and are subsequently coupled utilizing a wafer bonding technique to form the sensor device ( 184 ) The sensor portion ( 180 ) includes one or more sensors ( 186, 188 ), and the sensor portion ( 182 ) includes one or more sensors ( 236, 238 ) The sensors ( 186, 188 ) are located inside the chamber ( 270 ) facing the sensors ( 236, 238 ) also located inside the chamber ( 270 ) The sensors ( 186, 188, 236, 238 ) are configured to sense different physical stimuli, such as motion, pressure, and magnetic field

97 citations


Patent
16 Jul 2009
TL;DR: In this paper, the power management in a light emitting diode (LED) system having a plurality of LED strings is disclosed, where an LED driver monitors the tail voltages of the active LED strings to identify the minimum, or lowest, tail voltage and adjusts the output voltage of the voltage source based on the lowest tail voltage.
Abstract: Power management in a light emitting diode (LED) system having a plurality of LED strings is disclosed. A voltage source provides an output voltage to drive the LED strings. An LED driver monitors the tail voltages of the active LED strings to identify the minimum, or lowest, tail voltage and adjusts the output voltage of the voltage source based on the lowest tail voltage. The LED driver can adjust the output voltage so as to maintain the lowest tail voltage at or near a predetermined threshold voltage so as to ensure that the output voltage is sufficient to properly drive each active LED string with a regulated current in view of pulse width modulation (PWM) performance requirements without excessive power consumption.

92 citations


Journal ArticleDOI
TL;DR: Investigation of the intermetallic compound growth associated with Sn–0.7Cu and Sn–4.5Cu solders on Ni–Au, Ni–Pd, and Cu substrates found it affected the toughness and reliability of the solder joint, and the relationship between solder and intermetallics microstructure and mechanical properties is discussed.

81 citations


Patent
02 Feb 2009
TL;DR: In this paper, a method and apparatus for fabricating a high aspect ratio MEMS device by using metal thermocompression bonding to assemble a reference wafer, a bulk MEMS active wafer and a cap wafer was described.
Abstract: A method and apparatus are described for fabricating a high aspect ratio MEMS device by using metal thermocompression bonding to assemble a reference wafer (100), a bulk MEMS active wafer (200), and a cap wafer (300) to provide a proof mass (200 d) formed from the active wafer with bottom and top capacitive sensing electrodes (115, 315) which are hermetically sealed from the ambient environment by sealing ring structures (112/202/200 a/ 212/312 and 116/206/200 e/ 216/316).

79 citations


Journal ArticleDOI
TL;DR: A switched-capacitor low-distortion 15-level delta-sigma ADC achieves third-order noise shaping with only two integrators by using quantization noise coupling, which is among the best reported for discrete-time delta-Sigma ADCs in wideband applications.
Abstract: A switched-capacitor low-distortion 15-level delta-sigma ADC is described. It achieves third-order noise shaping with only two integrators by using quantization noise coupling. Realized in a 0.18 mum CMOS technology, it provides 81 dB SNDR, 82 dB dynamic range, and -98 dB THD in a signal bandwidth of 1.9 MHz. It dissipates 8.1 mW with a 1.5 V power supply (analog power 4.4 mW, digital power 3.7 mW). Its figure-of-merit is 0.25 pJ/conversion-step, which is among the best reported for discrete-time delta-sigma ADCs in wideband applications.

79 citations


Patent
19 Nov 2009
TL;DR: In this article, the electrodes are distributed so that a touch anywhere across the touch sensor panel is detected by at least one regional electrode and at least 1 local electrode, and the local electrodes are used to determine a more specific touch location within the determined region.
Abstract: An input sensor for an electronic device (100) which includes a touch sensor panel (104), multiple electrodes and a sensor circuit. The electrodes include multiple regional electrodes and multiple local electrodes. Each regional electrode covers a corresponding region of the touch sensor panel and each local electrode includes multiple pads including one pad located within each of the regional electrodes. The electrodes are distributed so that a touch anywhere across the touch sensor panel is detected by at least one regional electrode and at least one local electrode. A sensor circuit determines a value for each of the electrodes indicating relative change, and compares relative values of the electrodes to identify a location of a touch of the touch sensor panel. The regional electrodes are used to determine a region of a touch and the local electrodes are used to determine a more specific touch location within the determined region.

70 citations


Patent
30 Jan 2009
TL;DR: In this article, a feedback controller monitors the tail voltages of the LED strings to identify the minimum tail voltage and adjusts the output voltage based on the lowest tail voltage, which can be implemented in separate integrated circuit (IC) packages.
Abstract: Techniques for dynamic headroom control in a light emitting diode (LED) system are disclosed. An output voltage is provided to drive a plurality of LED strings. A feedback controller monitors the tail voltages of the LED strings to identify the minimum tail voltage and adjusts the output voltage based on the lowest tail voltage. The LED strings grouped into subsets and the feedback controller is segmented such that, for a certain duration, a minimum tail voltage is determined for each subset. The minimum tail voltages of the subsets are used to determine the overall minimum tail voltage of the plurality of LED strings for the certain duration so as to control the output voltage in the following duration. The segments of the feedback controller can be implemented in separate integrated circuit (IC) packages, thereby facilitating adaptation to different numbers of LED strings by integrating the corresponding number of IC packages.

Patent
13 Feb 2009
TL;DR: In this paper, an integrated circuit comprises frequency generation circuitry for controlling a frequency source for an automotive radar system, which comprises a Phase Locked Loop (PLL) arranged to generate a control signal for controlling the frequency source, a fractional-N divider located within a feedback loop of the PLL, and frequency pattern control logic operably coupled to the fractional N divider.
Abstract: An integrated circuit comprises frequency generation circuitry for controlling a frequency source for an automotive radar system The frequency generation circuitry comprises a Phase Locked Loop (PLL) arranged to generate a control signal for controlling the frequency source, a fractional-N divider located within a feedback loop of the PLL, and frequency pattern control logic operably coupled to the fractional-N divider and arranged to control the fractional-N divider, by way of a frequency control signal, such that the PLL generates a Frequency Modulated Continuous Wave (FMCW) control signal

Patent
30 Jan 2009
TL;DR: In this article, a voltage source provides an output voltage to drive a plurality of light emitting diode (LED) strings, and an LED driver adjusts the level of the output voltage so as to maintain the lowest tail voltage of the LED strings at or near a predetermined threshold voltage.
Abstract: A voltage source provides an output voltage to drive a plurality of light emitting diode (LED) strings. A LED driver adjusts the level of the output voltage so as to maintain the lowest tail voltage of the LED strings at or near a predetermined threshold voltage so as provide sufficient headroom voltages for current regulators for the LED strings. The LED driver operates in an operational mode and a calibration mode, which can be implemented in parallel with, or part of, the operational mode. During the calibration mode, the LED driver determines, for each LED string, a code value representative of the level of the output voltage necessary to maintain the tail voltage of the corresponding LED string at or near the predetermined threshold voltage. In the operational mode, the code values from the calibration mode are used to control the voltage source to provide an appropriate level for the output voltage.

Journal ArticleDOI
TL;DR: The research studies in the drop-impact reliability of solder joints in the PCB assemblies intended for mobile applications cover stress–strain characterisation of solders, evaluation of test methods at component and board levels, and investigation of the fatigue characteristics of solder Joints.

Journal ArticleDOI
TL;DR: In this paper, the authors demonstrate that the mechanism of recrystallization in arsenic implanted silicon is solid phase epitaxial regrowth, and that the boron implanted silicon samples did not result in enough lattice damage to amorphize the silicon lattice and resulted in low activation during microwave annealing.
Abstract: Microwaves are used as a processing alternative for the electrical activation of ion implanted dopants and the repair of ion implant damage within silicon. Rutherford backscattering spectra demonstrate that microwave heating reduces the damage resulting from ion implantation of boron or arsenic into silicon. Cross-section transmission electron microscopy and selective area electron diffraction patterns demonstrate that the silicon lattice regains nearly all of its crystallinity after microwave processing of arsenic implanted silicon. Sheet resistance readings indicate the time required for boron or arsenic electrical activation within implanted silicon. Hall measurements demonstrate the extent of dopant activation after microwave heating of implanted silicon. Physical and electrical characterization determined that the mechanism of recrystallization in arsenic implanted silicon is solid phase epitaxial regrowth. The boron implanted silicon samples did not result in enough lattice damage to amorphize the silicon lattice and resulted in low boron activation during microwave annealing even though recrystallization of the Si lattice damage did take place. Despite low boron activation levels, the level of boron activation in this work was higher than that expected from traditional annealing techniques. The kinetics of microwave heating and its effects on implanted Si are also discussed.

Patent
12 Mar 2009
TL;DR: In this paper, an equalizer and an RF modulator are used to compensate for offset frequency-dependent components of transmitter IQ imbalance by applying IQ gain and phase correction to the equalized samples.
Abstract: Embodiments include transceivers and transmit IQ imbalance correction methods. A transmitter lineup, which includes an equalizer and an RF modulator, receives a stream of baseband samples having real and imaginary components, processes the real components along a first channel, and processes the imaginary components along a second channel to produce processed real and imaginary components. The equalizer equalizes at least one of the processed real components and the processed imaginary components to compensate for offset frequency-dependent components of transmitter IQ imbalance. The RF modulator receives and modulates analog versions of the equalized samples, resulting in an analog RF signal. An embodiment also includes a balancer adapted to apply IQ gain and phase correction to the equalized samples to compensate for offset frequency-independent components of the transmitter IQ imbalance. A calibration processing subsystem determines filter coefficients used by the equalizer and IQ gain and phase correction values used by the balancer.

Patent
30 Jan 2009
TL;DR: A random number generator includes a first one time programmable (OTP) element and a second OTP element as mentioned in this paper, and a sense amplifier provides an output signal at a first logic state when the first value exceeds the second value.
Abstract: A random number generator includes a first one time programmable (OTP) element and a second OTP element. The first OTP element and second OTP element have a first distribution of probable values for an electrical characteristic when unprogrammed and a second distribution of probable values when programmed. A programming circuit applies a programming signal to the first OTP element and to the second OTP element that causes the first OTP element to switch from being unprogrammed to being programmed and having a first value for its electrical characteristic and the second OTP element to switch from being unprogrammed to being programmed and having a second value for its electrical characteristic. A sense amplifier provides an output signal at a first logic state when the first value exceeds the second value and at a second logic state when the second value exceeds the first value.

Patent
05 Jan 2009
TL;DR: In this article, a system comprises a signal processing logic that is operably coupled to at least one memory element and is arranged to enable access to the at least 1 memory element.
Abstract: A system comprises signal processing logic that is operably coupled to at least one memory element and is arranged to enable access to the at least one memory element. The signal processing logic is arranged to receive a security key, generate a system key using the received security key and a system specific seed, perform a comparison of the generated system key to a reference key stored in an area of memory of the at least one memory element. The signal processing logic is also arranged to configure a level of access to the at least one memory element based at least partly on the comparison of the generated system key to the reference key stored in memory.

Journal ArticleDOI
TL;DR: In this paper, the application of ion irradiation to induce nanocrystalization in a Cu50Zr45Ti5 (CZT) alloy was reported, where hardness enhancement was observed near the projected range of the He ions, coinciding with the formation of nanocrystals.
Abstract: Application of metallic glasses as structural materials has been limited by their poor ductility. To overcome brittle failure, nanocrystals are intentionally introduced to stabilize the glasses. In this study, we report on the application of ion irradiation to induce nanocrystalization in a Cu50Zr45Ti5 (CZT) alloy. Transmission electron microcopy, microindentation and nanoindentation have been used to characterize the CZT alloy irradiated with 140 keV He ions at room temperature. Hardness enhancement was observed near the projected range of the He ions, coinciding with the formation of nanocrystals. Such microstructural changes, however, were not observed in the near surface region, where the electronic stopping process is dominant.

Patent
10 Nov 2009
TL;DR: In this article, an advanced communication controller unit for a distributed communication system having a plurality of communication controller units, at least one being an Advanced Communication Controller Unit, each coupled to a communication medium and adapted to communicate using a communication is presented.
Abstract: An advanced communication controller unit for a distributed communication system having a plurality of communication controller units, at least one being an advanced communication controller unit, each coupled to a communication medium and adapted to communicate using a communication is presented. The advanced communication controller unit comprises a protocol event recording circuit having a monitoring input connected to at least one protocol event data transmission path of the advanced communication controller unit and a debug output connected to a memory device; and adapted to filter protocol event data received from the monitoring input depending on at least one configuration parameter and to provide filtered protocol event data to the debug output. A method for recording protocol events using a protocol event recording circuit in an advanced communication controller unit and a vehicle comprising at least one advanced communication controller unit are also disclosed.

Journal ArticleDOI
TL;DR: In this paper, the Hall resistivity of the films was as low as 6.9×10−5 Ω-cm with a carrier concentration of 1.2×1022 cm−3 at the optimum copper layer thickness.
Abstract: ZnO/Cu/ZnO multilayer structures with very high conductivity have been obtained by magnetron sputtering. The Hall resistivity of the films was as low as 6.9×10−5 Ω-cm with a carrier concentration of 1.2×1022 cm−3 at the optimum copper layer thickness. The conduction mechanism has been explained in terms of metal to oxide carrier injection at low copper thickness and metal layer conduction at higher Cu thicknesses. The peak transmittance of the films is 88% and the photopic averaged transmittance is 75%. Optical transmission behavior of the films involves absorption by copper due to d-band to Fermi-surface transitions at short wavelengths and reflectance combined with scattering losses at long wavelengths. A Burstein–Moss shift in the band gap of the films is seen to take place with increase in thickness of the copper layer. The Haacke figure of merit has been calculated for the films with the best value being 8.7×10−3 Ω−1. Pole figure results reveal that the copper midlayer acts as a hindrance to (002) Zn...

Patent
Bin Zhao1
30 Jan 2009
TL;DR: In this article, an open channel detection technique at a light emitting diode (LED) driver of an LED system is presented, where the LED driver does not enable its LED channels before normal operation so as to inhibit current flow through the LED channels during start-up.
Abstract: Disclosed are example open channel detection techniques at a light emitting diode (LED) driver of an LED system. The LED driver does not enable its LED channels before normal operation so as to inhibit current flow through the LED channels during start-up. While the LED channels are disabled, the LED driver compares the voltages at the LED channel inputs with a predetermined voltage to determine whether an operational LED string of an associated LED panel is connected to the LED channel. In the event that an LED channel is determined to be an “open” channel, the LED driver further disables the LED channel for the following normal operational mode. Otherwise, if the LED channel is determined to be connected to an operational LED string, the LED driver enables the LED channel for the normal operational mode, during which the LED channel can be selectively activated for light output subject to display data for the LED panel.

Patent
15 Apr 2009
TL;DR: In this paper, a signal for controlling a resonance frequency of the sense resonator is provided responsive to performing a Goertzel algorithm on the first base band signal and the second baseband signal.
Abstract: An inertial sensor has a transducer with a sense resonator. The sense resonator is oscillated. A signal responsive to the oscillation is provided. A first baseband signal and a second baseband signal are provided responsive to the signal responsive to the oscillation of the sense resonator. A signal for controlling a resonance frequency of the sense resonator is provided responsive to performing a Goertzel algorithm on the first baseband signal and the second baseband signal. One use of controlling the resonance frequency is to control an offset between the resonance frequency of the sense resonator and the frequency of the oscillation of drive masses in the sense resonator. Using the Goertzel algorithm is particularly efficient in controlling the resonance frequency.

Patent
12 Aug 2009
TL;DR: In this article, a method and apparatus are described for fabricating an exposed differential pressure sensor, which vents both sides of a piezoresistive transducer sensor diaphragm through a first vent hole formed in an exposed die flag and a second vent hole created by an exposed cap structure.
Abstract: A method and apparatus are described for fabricating an exposed differential pressure sensor ( 30 ) which protects interior electrical components ( 37 ) formed on a topside surface of a differential pressure sensor transducer die ( 31 ) from corrosive particles using a molding compound ( 39 ), but which vents both sides of a piezoresistive transducer sensor diaphragm ( 33 ) through a first vent hole ( 42 ) formed in an exposed die flag ( 36 ) and a second vent hole ( 38 ) formed in an exposed cap structure ( 33 ), enabling the sensor diaphragm ( 33 ) to sense differential pressure variations directly or indirectly through a protective gel.

Patent
20 May 2009
TL;DR: In this article, a gate electrode is formed over the source/drain layer of a GaN layer on a first surface of a substrate, where the bulk GaN transistor region and a BAW device region are formed.
Abstract: A bulk GaN layer is on a first surface of a substrate, wherein the bulk GaN layer has a GaN transistor region and a bulk acoustic wave (BAW) device region. A source/drain layer is over a first surface of the bulk GaN layer in the GaN transistor region. A gate electrode is formed over the source/drain layer. A first BAW electrode is formed over the first surface of the bulk GaN layer in the BAW device region. An opening is formed in a second surface of the substrate, opposite the first surface of the substrate, which extends through the substrate and exposes a second surface of the bulk GaN layer, opposite the first surface of the bulk GaN layer. A second BAW electrode is formed within the opening over the second surface of the bulk GaN layer.

Patent
06 May 2009
TL;DR: In this paper, an apparatus, method and program for outputting a present position that enables a user to be located with further accuracy even in a multi-level area is presented.
Abstract: An apparatus, method and program for outputting a present position that enables a user to be located with further accuracy even in a multi-level area. A control unit periodically sends a reference atmospheric pressure information obtaining request to a base station and obtains reference atmospheric pressure information including the atmospheric pressure and altitude of the base station from the base station and stores the obtained information in a data storage. The control unit uses the measurement value of atmospheric pressure obtained from a pressure sensor and an altitude calculation equation including the reference atmospheric pressure information to periodically calculate and record in the data storage the altitude of the present position. When an emergency button is pushed, the control unit issues to an emergency contact an emergency notification including the present altitude or the altitude recorded in the data storage.

Patent
24 Nov 2009
TL;DR: In this article, a data communication method is provided, comprising: processing high-speed digital data for communication to produce processed data; generating short impulse wavelets; constructing a digitally modulated ultra wideband signal from the short impulsewavelets in response to bits of the processed data, wherein the value of each bit of processed data is digitally modified onto the shape of at least one of the short wavelet of the series, to produce a series of digitally shape modulated impulse wavelet.
Abstract: A data communication method is provided, comprising: processing high-speed digital data for communication to produce processed data; generating short impulse wavelets; constructing a digitally modulated ultra wideband signal from the short impulse wavelets in response to bits of the processed data, wherein the digitally modulated ultra wideband signal comprises a series of the short impulse wavelets, and the value of each bit of the processed data is digitally modulated onto the shape of at least one of the short impulse wavelets of the series, to produce a series of digitally shape modulated impulse wavelets; and transmitting the digitally modulated ultra wideband signal, including the series of digitally shape modulated impulse wavelets, via an antenna.

Patent
Bin Zhao1
09 Feb 2009
TL;DR: In this article, a power management technique in a light emitting diode (LED) system is described, which includes a plurality of LED driver connected in series, each LED driver configured to regulate the current flowing through a corresponding subset of the LED strings.
Abstract: A power management technique in a light emitting diode (LED) system is disclosed. The LED system includes a plurality of LED driver connected in series, each LED driver configured to regulate the current flowing through a corresponding subset of a plurality of LED strings. Each LED driver determines the minimum tail voltage of the LED strings of the corresponding subset, compares the determined minimum tail voltage with an indicator of a minimum tail voltage of one or more other subsets provided from an upstream LED driver in the series, and then provides an indicator of the lower of the two tail voltages to the downstream LED driver. In this manner an indicator of the minimum tail voltage of the plurality of LED strings is cascaded through the series. A feedback controller monitors the minimum tail voltage represented by the cascaded indicator and accordingly adjusts an output voltage provided to the head ends of the plurality of LED strings.

Proceedings ArticleDOI
26 May 2009
TL;DR: In this paper, the reliability of low Ag SAC alloys doped with Mn or Ce (SACM or SACC) were evaluated under JEDEC drop, dynamic bending, thermal cycling, and cyclic bending test conditions against eutectic SnPb, SAC105, and SAC305 alloys.
Abstract: In this study, the reliabilities of low Ag SAC alloys doped with Mn or Ce (SACM or SACC) were evaluated under JEDEC drop, dynamic bending, thermal cycling, and cyclic bending test conditions against eutectic SnPb, SAC105, and SAC305 alloys. The Mn or Ce doped low cost SAC105 alloys achieved a higher drop test and dynamic bending test reliability than SAC105 and SAC305, and exceeded SnPb for some test conditions. More significantly, being a slightly doped SAC105, both SACM and SACC matched SAC305 in thermal cycling performance. In other words, the low cost SACM and SACC achieved a better drop test performance than the low Ag SAC alloys plus the desired thermal cycling reliability of high Ag SAC alloys. The mechanism for high drop performance and high thermal cycling reliability can be attributed to a stabilized microstructure, with uniform distribution of fine IMC particles, presumably through the inclusion of Mn or Ce in the IMC. The cyclic bending results showed SAC305 being the best, and all lead-free alloys are equal or superior to SnPb. The reliability test results also showed that NiAu is a preferred surface finish for BGA packages over OSP.

Journal ArticleDOI
TL;DR: In this paper, the electrical properties of Ga2O3/GaAs interfaces with GdGaO cap dielectrics used in recent enhancement-mode GaAs-based NMOSFETs which perform in line with theoretical model predictions are presented.
Abstract: Electrical properties of Ga2O3/GaAs interfaces with GdGaO cap dielectrics used in recent enhancement-mode GaAs-based NMOSFETs which perform in line with theoretical model predictions are presented. Capacitors with GdGaO thickness ranging from 3.0 to 18 nm (0.9 les EOT les 3.9 nm) have been characterized by capacitance-voltage measurements. Midgap interface state density Dit, effective workfunction phim, fixed charge Qf, dielectric constant kappa, and low field leakage current density are 2 times1011 cm-2 middoteV-1, 4.93 eV, -8.9 times1011 cm-2, 19.5, and 10-9- 10-8 A/cm2, respectively. The presence of interfacial Gd was confirmed to dramatically degrade electrical interface properties. The data illuminate the intimate interplay between heterostructure and interface engineering to achieve optimum MOSFET operation.