|Publication number||US7693494 B2|
|Application number||US 11/296,148|
|Publication date||Apr 6, 2010|
|Filing date||Dec 6, 2005|
|Priority date||Dec 6, 2005|
|Also published as||US20070129030|
|Publication number||11296148, 296148, US 7693494 B2, US 7693494B2, US-B2-7693494, US7693494 B2, US7693494B2|
|Inventors||Petteri M. Litmanen, Heng-Chih Lin|
|Original Assignee||Texas Instruments Incorporated|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (7), Referenced by (9), Classifications (25), Legal Events (2)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The present invention relates to the field of data communications and more particularly relates to a high dynamic range pre-power amplifier incorporating a digital attenuator for use in the transmitter portion of a Digital RF Processor or Digital Radio Processor (DRP).
It is well known in the communication arts that a transmit (Tx) buffer is required for both wired and wireless communications systems to interface the transmit path signal to the outside environment. In many cases, the transmit buffer is required to apply a variable gain to the transmit signal in order to increase or reduce the amplitude of the output signal. One such case occurs when the transmitted signal is part of an amplitude modulated communication system and the transmit buffer itself is used to implement the amplitude modulation function. The signal to noise ratio (SNR) requirements of such Tx buffers in most systems are extremely strict, meaning that any amplitude control circuitry should contribute no more than negligible noise to the buffer output. The reverse isolation (which can also be considered gain accuracy at low gain levels) of such transmit buffers is also an important concern. In addition, the current consumption requirements for these transmit buffers are limited such that any gain control scheme cannot ‘burn’ or waste current in order to meet the power consumption budget and the strict signal to noise requirements stated above.
A prior art digitally controlled near class E power amplifier designed for the Bluetooth wireless communication standard provides a limited number of bits for amplitude control (e.g., only 3.5 bits of amplitude control) and is used for power regulation of the transmitted constant envelope RF output. The previous lowest reported power consumption for a prior art GSM transmit chain, having no power control, is 17 mW with −7 dBm output power. The design for such a system has a transmitted power efficiency of 2.7% for an output power of 0 dBm.
There exist in the prior art multiple transmit chain architectures for transforming a digitally encoded bit stream into an RF modulated waveform at a power level suitable for transmission. The transmit power level for a cellular transceiver integrated circuit (IC) is typically around 3 dBm for interfacing with external power amplifiers (PAs). This output power level, however, is not constant in amplitude-modulated standards, such as EDGE, and must be controlled with appropriate variable-gain circuitry. Typical prior art architectures, such as single-sideband upconversion, perform digital-to-analog conversion on-chip and employ a variable gain pre-power amplifier (PPA) to transmit the required signal at the desired power level. In these architectures, the overall power consumption of the transmit chain, including all the DAC and variable gain buffer components, is at least 50 mW which is a relatively high amount of power. It is desirable to be able to reduce the power consumption of the transmit chain significantly.
All digital CMOS pre-power amplifiers exist in the art. A pre-power amplifier is designed to generate an output signal having desired waveform characteristics that is fed into the final power output stage before being transmission over the wireless channel. Previous CMOS pre-power amplifiers have typically been designed for relatively low dynamic range wireless standards such as Bluetooth and GSM/GPRS. High dynamic range wireless standards such as WCDMA or CDMA2000 require approximately 100 dB of dynamic range which represents an additional 30-40 dB over the Bluetooth and GSM/GPRS wireless standard dynamic range requirements.
There is thus a long felt need for a pre-power amplifier having high dynamic range that is able to meet the more demanding dynamic range requirements of high dynamic range wireless standards such as WCDMA and CDMA2000, for example. In addition, the pre-power amplifier should be able to be implemented using digital CMOS processes.
The present invention provides a solution to the problems of the prior art by providing a pre-power amplifier incorporating a digital attenuator circuit. The digital attenuator and associated pre-power amplifier are presented in the context of an all digital direct digital-to-RF amplitude converter (DRAC), which efficiently combines the traditional transmit chain functions of upconversion, I and Q combining, D/A conversion, filtering, buffering and RF output amplitude control into a single circuit.
The attenuator circuit functions to extend the dynamic range of the pre-power amplifier sufficient to enable implementation of more demanding wireless standards, such as WCDMA and CDMA2000, using digital CMOS processes. Use of the attenuator circuit enables the pre-power amplifier to exhibit over 100 dBm of dynamic range.
Increased dynamic range is achieved by the present invention by placing a digital current attenuator circuit at the output of the pre-power amplifier (PPA). The attenuator is placed at the output so that the minimum possible current output of the transistor switch array of the PPA can be further attenuated. The attenuator functions to split the current between the load and the power Supply VDD (i.e. AC ground) based on device ratio that is controlled digitally via an input power control word.
The digital attenuator is constructed as a segmented digitally controlled matrix or cell array comprising at least a pass and bypass matrix or array. Segmentation is dictated by the desire for small power control steps. The pass matrix controls the amount of current output from the PPA while the bypass matrix controls the amount of current shorted to the AC ground (i.e. power supply). By varying the number of transistors on or off in each matrix, the power output of the PPA can be easily and accurately controlled.
Several advantages of the attenuator include (1) guaranteed monotonicity, (2) power control is achieved without the need for a DAC, (3) minimum noise degradation, and (4) parasitic capacitance will not dominate the output assuming moderate attenuation of approximately 20 dB.
Note that many aspects of the invention described herein may be constructed as software objects that are executed in embedded devices as firmware, software objects that are executed as part of a software application on either an embedded or non-embedded computer system such as a digital signal processor (DSP), microcomputer, minicomputer, microprocessor, etc. running a real-time operating system such as WinCE, Symbian, OSE, Embedded LINUX, etc. or non-real time operating system such as Windows, UNIX, LINUX, etc., or as soft core realized HDL circuits embodied in an Application Specific Integrated Circuit (ASIC) or Field Programmable Gate Array (FPGA), or as functionally equivalent discrete hardware components.
There is thus provided in accordance with the invention, a current attenuator for increasing the dynamic range of a signal generated by a circuit, comprising pass means for controlling the amount of current generated by the circuit that is passed through to the output of the circuit and bypass means for shorting a portion of current generated by the circuit to AC ground thereby reducing the signal output from the circuit.
There is also provided in accordance with the invention, a pre-power amplifier, comprising a load coupled to a power source, a switch array comprising a plurality of switches, the switch array for generating a current proportional to the number of switches active therein and an attenuator coupled to the load and the switch array and adapted to further attenuate the minimum current generated by the switch array.
There is further provided in accordance with the invention, a pre-power amplifier, comprising a load coupled to a power source, a switch array comprising a plurality of switches, the switch array for generating a current proportional to the number of switches active therein, an attenuator coupled to the load and the switch array comprising pass means for controlling the amount of current generated by the switch array that is passed through to the output of the pre-power amplifier and bypass means for shorting a portion of current generated by the switch array to AC ground thereby reducing signal to the output of the pre-power amplifier.
There is also provided in accordance with the invention, a pre-power amplifier, comprising a load coupled to a power source, a switch array comprising a plurality of switches, the switch array for generating a current proportional to the number of switches active therein and an attenuator for increasing the dynamic range of the switch array, the attenuator comprising a pass transistor cell array coupled in series to the load and the switch array and operative to control the amount of current generated by the switch array that is passed through to the output of the pre-power amplifier, a bypass transistor cell array coupled to the switch array and AC ground and operative to short a portion of current generated by the switch array to AC ground thereby reducing signal to the output of the pre-power amplifier.
The invention is herein described, by way of example only, with reference to the accompanying drawings, wherein:
The following notation is used throughout this document.
Application Specific Integrated Circuit
Code Division Multiple Access
Complementary Metal Oxide Semiconductor
Digital to Analog Converter
Digital Controlled Oscillator
Dynamic Element Matching
Digital Power Amplifier
Digital Phase Locked Loop
Digital to RF Amplitude Converter
Digital RF Processor or Digital Radio Processor
Digital Signal Processor
Enhanced Data rates for Global Evolution
Field Programmable Gate Array
General Packet Radio Service
Global System for Mobile Communication
Least Significant Bit
Look Up Table
Most Significant Bit
n-channell Field Effect Transistor
n-channel Metal Oxide Semiconductor
p-channel Metal Oxide Semiconductor
Process Voltage Temperature
Surface Acoustic Wave
Signal to Noise Ratio
Variable Gain Amplifier
Wideband Code Division Multiple Access
The present invention is a pre-power amplifier having high dynamic range. The pre-power amplifier is suitable for use with wireless standards such as WCDMA and CDMA2000 that demand high dynamic range transmitters. The invention is intended for use in a digital radio transmitter and receiver but can be used in other applications as well, such as a general communication channel. The present invention provides a solution to the problems of the prior art by providing an apparatus for a high dynamic range pre-power amplifier scheme for a transmitter. The dynamic range improvement circuitry is presented in the context of an all digital direct digital-to-RF amplitude converter (DRAC) or pre-power amplifier (PPA), which efficiently combines the traditional transmit chain functions of upconversion, I and Q combining, D/A conversion, filtering, buffering and RF output amplitude control into a single circuit.
To aid in understanding the principles of the present invention, the description is provided in the context of a digital to RF amplitude converter (DRAC) that serves as the final stage of an all-digital polar transmitter IC for WCDMA/CDMA2000. It is appreciated by one skilled in the art that the dynamic range improvement circuitry and pre-power amplifier of the present invention can be adapted to comply with numerous wireless communications standard such as GSM, extended data rate Bluetooth, WCDMA, CDMA2000, etc. It is appreciated, however, that the invention is not limited for use with any particular communication standard (wireless or otherwise) and may be used in optical, wired and wireless applications. Further, the invention is not limited for use with a specific modulation scheme but is applicable to other modulation schemes as well.
The term pre-power amplifier (PPA) is intended to include a transmit buffer as well as various amplifier circuits such as digital to RF amplitude converter (DRAC), digital power amplifier (DPA), transmit buffer, low power amplifier, high power amplifier, etc. and it not intended to be limited by the amount of power produced.
Note that throughout this document, the term communications device is defined as any apparatus or mechanism adapted to transmit, receive or transmit and receive data through a medium. The communications device may be adapted to communicate over any suitable medium such as RF, wireless, infrared, optical, wired, microwave, etc. In the case of wireless communications, the communications device may comprise an RF transmitter, RF receiver, RF transceiver or any combination thereof.
A block diagram illustrating an example embodiment of a polar transmitter and DRAC incorporating the high dynamic range pre-power amplifier of the present invention is shown in
In digital polar transmission, the I and Q data signals are converted by the cordic into amplitude and phase signals in the polar domain. The amplitude signal undergoes further digital processing in the digital portion (not shown) of the polar transmitter. The phase signal is input to the DPLL which incorporates a digitally controlled oscillator (DCO) for upconversion of the input phase signal. The processed amplitude signal and the phase signal output from the DPLL are both input to the DPA. The DPA functions to combine the digital amplitude and upconverted phase information into an analog transmit signal. The DPA also incorporates ΣΔ (sigma-delta) modulation to enhance the amplitude resolution and to achieve noise spectral shaping. The DRAC also performs dynamic element matching (DEM) to enhance time-averaged linearity. The SAW or other type of filter functions to suppress out of band PPA thermal and quantization noise before final amplification by the power amplifier.
A circuit diagram illustrating a pre-power amplifier utilizing a switch array but without dynamic range improvement is shown in
A circuit diagram illustrating an example embodiment of the switch array of
A graph illustrating the output power of the digital power amplifier without the dynamic range improvement circuitry of the present invention is shown in
Pre-power amplifiers such as shown in
The present invention provides a solution to this problem by providing a dynamic range improvement circuit comprising an attenuator to extend the dynamic range of the PPA. Use of the attenuator circuit of the present invention in the PPA provides sufficient improvement in dynamic range to meet the demanding requirements of high dynamic range wireless standards such as WCDMA and CDMA20000.
A block diagram of a pre-power amplifier incorporating the dynamic range improvement circuit of the present invention is shown in
The switch array is made up of transistor cells having a certain minimum size. The minimum amount of current generated by the switch array on its own is too high which results in insufficient dynamic range at the PPA output. The attenuator functions to reduce this current further in accordance with the input power control word. Note that the switch matrix may comprise any suitable circuit that is capable of generating a current or voltage in proportion to an input amplitude control word.
A circuit diagram illustrating an example embodiment of the pre-power amplifier incorporating the dynamic range improvement circuitry of the present invention in more detail is shown in
As described above, the limiting factor for high dynamic range PPAs is the size of the minimum controllable power. A single minimum size NFET can provide approximately −40 dBm of output power which can be decreased further to −70 dBm by the use of sigma-delta dithering. High dynamic range systems, however, require a lower minimum output power of close to −90 dBm. The present invention utilizes a current attenuator at the output of the PPA such that the minimum current possible from the NFET switch matrix can be further attenuated. In operation, the attenuator splits the output current between the load and VDD (i.e. AC ground) based on a digitally controlled device ratio which is dictated by an input power control word and reflected in the number of transistors turned on or off in the pass and bypass matrices. This attenuation scheme enables PPAs constructed in CMOS processes to achieve a very high and well controlled dynamic range.
In the example embodiment presented herein, the digital attenuator is constructed as a segmented digitally controlled matrix or cell array comprising at least a pass and bypass array. Segmentation is dictated by the desire for small power control steps. Advantages of the attenuator include (1) guaranteed monotonicity, (2) power control is achieved without the need for a DAC, (3) minimum noise degradation, and (4) parasitic capacitance will not dominate the output assuming moderate attenuation of approximately 20 dB.
A circuit diagram illustrating an example embodiment of the attenuator and switch array portions of the pre-power amplifier in more detail is shown in
The attenuator 102 comprises a pass matrix 114 and bypass matrix 116. In this embodiment, a third base matrix 112 is used as well. The base matrix is connected in parallel with the pass matrix. During normal operation, all the cell or transistor elements of the base matrix are on. Use of the base matrix creates a sufficient signal path thus making reasonable power steps possible. By reducing the number of active base transistor elements, the attenuator step size can be increased. At the same time, however, the total dynamic range increases until physical limits are ultimately reached. If the dynamic range becomes too high, parasitic capacitance begins to limit the output and further improvements in dynamic range are ineffective.
As described supra, the pass matrix controls the amount of current passing through to the output and the bypass matrix controls how much current is shorted to the power supply (i.e. AC ground). Both matrices function in combination provide power control of the PPA output. Minimum power output is achieved with maximum attenuation which is realized when all pass matrix transistors are off (minimum current to the output) and all bypass matrix transistors are on (maximum shorting current). Maximum power output is achieved with minimum attenuation which is realized when all pass matrix transistors are on (maximum current to the output) and all bypass matrix transistors are off (minimum shorting current). Output power is controlled between the minimum and maximum by turning on the transistors in the pass and bypass matrices in different ratios in accordance with the desired output power.
To aid in understanding the operation of the invention, the attenuator circuit is divided into two phases of operation. Phase 1 is operative from minimum output power to half power and phase 2 is operative from half power to maximum output power. Phase 1 operation is described below followed by a description of phase 2 operation.
A diagram illustrating the transistor turn on path of the pass and bypass matrices in phase 1 operation of the attenuator is shown in
The uniqueness of each row requires the rows to be turned on in a particular order. At the lowest possible output power the entire pass matrix is turned off and the bypass matrix is turned on. As the output power is increased, the smallest transistors are turned on in accordance with their size starting with the smallest cell. When the entire matrix is turned on, the attenuator is at half (i.e. middle) attenuation of about 10 dB.
Several techniques can be used to improve dynamic element matching (DEM) from one attenuator step to the next. Dynamic element matching functions to reduce device mismatch between adjacent codes whereby switching between adjacent transistors is performed in the actual implementation. By way of example only, considering the matrix, increasing output power values translate to additional transistors being turned on. To compensate for mismatches between transistors due to process, voltage and temperature (PVT), as the end of a row is reached, the path continues with the next row but in the opposite direction. Rather than returning to the beginning of the next row when the end of a row is reached, the next row below is traversed in the opposite direction. This results in the snake like path shown in
Further, dummy cells are placed before the beginning and after the end of each row resulting in two extra columns of transistors. Each row has its own dummy unit cell terminations which aid in reducing mismatches between devices.
The bypass matrix is constructed and operates similarly as the pass matrix. One difference is that as power is increased up to the middle point (i.e. phase 1 operation), the bypass matrix elements are all on. At mid attenuation, both pass and bypass matrices are fully on. As the power is increased further, the pass matrix remains fully on but the bypass matrix elements are turned off beginning with the largest elements. In operation, the operation of the bypass matrix is in reverse order to that of the pass matrix.
The total power control range of the attenuator is shown in
A diagram illustrating the transistor turn off path of the pass and bypass matrices in phase 2 operation of the attenuator is shown in
A block diagram illustrating an example embodiment of a polar transmitter and DRAC incorporating the high dynamic range digital pre-power amplifier with power control lookup table of the present invention is shown in
For polar transmission, the I and Q data signals are converted by the cordic into amplitude and phase signals in the polar domain. The amplitude signal undergoes scaling and is split into an integer portion and a fractional portion. The integer portion is input to the DPA and the fractional portion is input to the ΣΔ (sigma-delta) modulator. Sigma-delta modulation is used to enhance the amplitude resolution and to achieve noise spectral shaping. The phase signal is input to the DPLL which incorporates a digitally controlled oscillator (DCO) for upconversion of the input phase signal. The processed amplitude signal and the phase signal output from the DPLL are both input to the DPA. The DPA, incorporating the attenuation circuit of the present invention, functions to combine the integer portion of the digital amplitude, upconverted phase information and output of the sigma-delta modulator into an analog transmit signal.
The power control uses a look up table (LUT) to provide control over the output power generated by the DPA. A power control code determines the amount of output power to be generated. Based on the power control code, the pass and bypass matrices are configured to achieve the desired output power dynamic range. The power control unit 142 provides a scaling adjustment signal that is used by the scaler, a phase adjustment signal used by the DPLL and the pass and bypass matrix control bits that determine the number of elements on or off in each matrix.
A graph illustrating the digital pre-power amplifier output at different attenuations is shown in
A graph illustrating the dynamic range of the digital pre-power amplifier output at minimum and maximum attenuation is shown in
A graph illustrating the pre-power amplifier output power as a function of the power control code is shown in
It is intended that the appended claims cover all such features and advantages of the invention that fall within the spirit and scope of the present invention. As numerous modifications and changes will readily occur to those skilled in the art, it is intended that the invention not be limited to the limited number of embodiments described herein. Accordingly, it will be appreciated that all suitable variations, modifications and equivalents may be resorted to, falling within the spirit and scope of the present invention.
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|Citing Patent||Filing date||Publication date||Applicant||Title|
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|US9118288 *||May 13, 2014||Aug 25, 2015||Mediatek Inc.||Digitally-controlled power amplifier with bandpass filtering/transient waveform control and related digitally-controlled power amplifier cell|
|US9306504||Jun 28, 2012||Apr 5, 2016||Qualcomm Incorporated||Waveform shaping for audio amplifiers|
|US20080219378 *||Mar 6, 2007||Sep 11, 2008||Sudhir Aggarwal||Low power wireless communication system|
|US20090034653 *||Oct 30, 2007||Feb 5, 2009||Ahmadreza Rofougaran||Method and system for polar modulation with discontinuous phase|
|US20110177789 *||Jan 20, 2010||Jul 21, 2011||Wang Chi Cheng||Low noise amplifier and the uses thereof|
|US20140240047 *||May 13, 2014||Aug 28, 2014||Mediatek Inc.||Digitally-controlled power amplifier with bandpass filtering/transient waveform control and related digitally-controlled power amplifier cell|
|U.S. Classification||455/91, 330/284, 455/114.3, 375/295, 375/297, 455/127.1|
|International Classification||H04B1/04, H01Q11/12|
|Cooperative Classification||H03F2200/331, H03G3/001, H03F3/211, H03F1/0277, H03F3/72, H03F2203/21145, H03F2200/366, H04B1/0483, H03F1/0205, H03G1/0088|
|European Classification||H03G3/00D, H04B1/04P, H03G1/00B8, H03F1/02T, H03F3/72, H03F1/02T3, H03F3/21C|
|Dec 6, 2005||AS||Assignment|
Owner name: TEXAS INSTRUMENTS INCORPORATED, TEXAS
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:LITMANEN, PETTERI M.;LIN, HENG-CHIH;REEL/FRAME:017319/0815;SIGNING DATES FROM 20051201 TO 20051202
Owner name: TEXAS INSTRUMENTS INCORPORATED,TEXAS
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:LITMANEN, PETTERI M.;LIN, HENG-CHIH;SIGNING DATES FROM 20051201 TO 20051202;REEL/FRAME:017319/0815
|Sep 25, 2013||FPAY||Fee payment|
Year of fee payment: 4


Lichee Tang 64Mbit SDRAM Onboard FPGA Downloader Dual Flash Core Board RISC-V Development Board Mini PC
Lichee Tang uses Anlogic Technologies' EG4S20 as the core unit, 20K logic unit (LUT4/LUT5 hybrid architecture), approximately 130KB SRAM, built-in 32bit bit width 64MBit SDRAM, rich LVDS pin, built-in 12-bit 1MSPS ADC.
– FPC40P, can be connected to RGB LCD, VGA adapter board, high speed DAC module
– FPC24P, can be connected to DVP camera, high speed ADC module
– Support resistive touch screen controller for I2C interface, used with RGB LCD
– 3-channel DCDC power supply chip, stable and efficient power supply, independent adjustment of Bank0 IO level
– FPGA configuration Flash, 8Mbit
– User Flash, nor/nand optional
– Onboard FPGA JTAG Download Debugger
– RGB LED
– Dual row pin spacing 900mil, compatible with breadboard development.
1x Lichee Tang board


Digital fringe projection technique is widely used in industrial applications with high accuracy and measurement speed. In this study, a fully automatic high-speed digital fringe projection technique is presented to profile 3D facial characteristics. The structured light with fringe pattern is used to be the light source in the measurement system and is projected by a digital light processing projector. The distorted fringe patterns from facial surface are captured by the digital camera. The absolute phase maps are calculated by using phase-shifting and quality guided path unwrapping algorithm. A complete, 3D facial feature is obtained by our measurement. We achieved simultaneous phase acquisition, reconstruction and three-dimensional (3D) exhibition at a speed of 0.5s. This technique may provide a high accuracy and real-time 3D facial measurement for biometric verification.
|期刊||Journal of Mechanics in Medicine and Biology|
|出版狀態||Published - 1 3月 2019|


Biointegrated intracellular microlasers have emerged as an attractive and versatile tool in biophotonics. Different inorganic semiconductor materials have been used for the fabrication of such biocompatible microlasers but often operate at visible wavelengths ill-suited for imaging through tissue. Here, we report on whispering gallery mode microdisk lasers made from a range of GaInP/AlGaInP multi-quantum well structures with compositions tailored to red-shifted excitation and emission. The selected semiconductor alloys show minimal toxicity and allow the fabrication of lasers with stable single-mode emission in the NIR (675-720 nm) and sub-pJ thresholds. The microlasers operate in the first therapeutic window under direct excitation by a conventional diode laser and can also be pumped in the second therapeutic window using two-photon excitation at pulse energies compatible with standard multiphoton microscopy. Stable performance is observed under cell culturing conditions for 5 days without any device encapsulation. With their bio-optimized spectral characteristics, low lasing threshold, and compatibility with two-photon pumping, AlGaInP-based microlasers are ideally suited for novel cell tagging and in vivo sensing applications.


Determination of Optimal Microminiature Powder Injection Molding Parameters by Taguchi Approach
The global manufacturing trend is now focusing towards miniaturization. Microminiature Powder Injection Molding (μPIM) is a viable technology to fabricate complex and high performance miniaturized components. The μPIM technique was used to produce the near-net shape micro components in this study. Fine stainless steel powder with particle size of 5μm was mixed with a ternary water-based binder system. Micro dumbbells with the largest dimension of 9mm were replicated. In order to obtain successful and well molded micro dumbbells, the Design of Experiments (DOE) technique was applied to investigate the optimal parameters in injection molding process. Injection parameters such as injection pressure (A), injection temperature (B), powder loading (C), mold temperature (D), injection time (E) and holding time (F) were optimized by using stainless steel feedstocks. Taguchi approach is chosen and the results were evaluated with signal-to-noise (SN) ratio and analysis of variance (ANOVA). The results show that the feedstocks could be replicated by using μPIM method with the application of Taguchi approach.
Zhengyi Jiang, Shanqing Li, Jianmin Zeng, Xiaoping Liao and Daoguo Yang
H. P. Li and N. Muhamad, "Determination of Optimal Microminiature Powder Injection Molding Parameters by Taguchi Approach", Advanced Materials Research, Vols. 189-193, pp. 2997-3000, 2011


|Publication number||US5820948 A|
|Application number||US 08/609,242|
|Publication date||Oct 13, 1998|
|Filing date||Mar 1, 1996|
|Priority date||Mar 7, 1995|
|Also published as||CA2171126A1, DE69609880D1, DE69609880T2, EP0731188A2, EP0731188A3, EP0731188B1|
|Publication number||08609242, 609242, US 5820948 A, US 5820948A, US-A-5820948, US5820948 A, US5820948A|
|Inventors||Hideo Itozaki, Tatsuoki Nagaishi|
|Original Assignee||Sumitomo Electric Industries, Ltd.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (14), Non-Patent Citations (4), Referenced by (11), Classifications (17), Legal Events (4)|
|External Links: USPTO, USPTO Assignment, Espacenet|
1. Field of the Invention
The present invention relates to a deposition process via laser ablation. More particularly, the present invention is suitable for forming electronic and microwave devices comprising oxide compounds.
2. Related Background Art
Laser ablation is one of the most suitable deposition process for producing excellent quality of thin films on substrate or workpiece. Laser ablation process has advantages, such as excellent stoichiometric stability of deposited film, when the process is used for depositing films of complex metal oxide compounds such as Y1 Ba2 Cu3 O7-X. There is another advantage in Laser ablation processing that it requires no electromagnetic fields which may possibly affect the charged particle contained in the deposited film. Therefore, laser ablation is expected to be employed as deposition process for the most promising nearterm devices.
Higaki et al (Institute of Electronics, Information and Communication Engineers, advanced conference paper, Apr. 26, 1991, hereinafter called "Reference 1") describes that a planar-type disk resonator formed when a thin layer of Y1 Ba2 Cu3 O7-X (referred to as "YBCO") is deposited by sputtering has excellent characteristics for the use in the microwave/millimeter-wave fields, such as temperature dependence of the surface resistance.
As described in the Reference 1, qualities of a thin film of oxides, such as crystallinity, are particularly important for microwave devices.
FIG. 5 shows an exploded perspective view of a resonator disclosed in the Reference 1. As shown in FIG. 5, a resonator 100 in accordance with Reference 1 has a configuration, in which a center dielectric layer 108 having a circular thin film 106 and rectangular thin films 107a and 107b thereon is sandwitched between an underlying lower dielectric layer 104 having a lower ground plane 102 of a gold thin film on its surface and an overlying upper dielectric layer 112 having an upper ground plane 110 of a gold thin film, by adhesion of these dielectric layers.
However, since the center dielectric layer is adhered to both the upper and the lower dielectric layer to form the device, high-frequency characteristics of the device may be affected with the adhesion condition.
Holzapfel et.al. describes that c-axis oriented epitaxial thin films of YBa2 Cu3 O7-X had been formed on both the front and the back surfaces of a substrate having (100) plane of LaAlO3 and SrTiO3 by the laser ablation of off-axis arrangement Holzapfel, B, et al., Applied Physics Letters, 61(26), pp. 3178-3180, 28 Dec. 1992, hereinafter called "Reference 2"!. The disclosure of the Holzapfel et.al. is hereby incorporated by reference.
The Reference 2 suggests a possibility of forming thin films of oxides on both upper and lower surfaces of a dielectric substrate, thereby forming ground planes onto the dielectric substrate to produce resonator. However, Reference 2 does not describe any useful method for forming acceptable films on both upper and lower surfaces in one process for superior electronic or microwave devices.
Therefore, it is desirable to provide a method for forming more reliable member used for microwave devices by employing laser ablation.
The apparatus for depositing thin films on both a first surface and a second surface of the substrate according to present invention comprises (1) a vacuum chamber which is thermally resistant at a temperature of 200° C., the vacuum chamber having (a) a first target of a first deposition material supported by a first target holder, (b) a second target of a second deposition material supported by a second target holder so as to positioned to be substantially coplanar with the first target, (c) a substrate holder for holding a substrate above a space between the first and second targets, the substrate being oriented to be substantially perpendicular to the targets, (d) a heating means for heating the first and second surfaces of the substrate, (e) a first entrance window through which a first laser beam passes to impinge onto the first target with a predetermined angle, and (f) a second entrance window through which a second laser beam passes to impinge onto the second target with a predetermined angle and (2) a laser optical system comprising at least one laser beam source and an optical path system from said laser beam source to said targets, the optical path system including mirrors for reflecting the laser beams toward the targets through the first and second entrance windows of the chamber.
The method for depositing thin films according to the present invention comprises the steps of, (a) disposing a first target and a second target within the vacuum chamber, the first target being positioned to be substantially coplanar with the second target; (b) disposing a substrate above a space between the first and second targets, the substrate is oriented to be substantially perpendicular to the targets; (c) heating the substrate with a heating means; and (d) directing the first and second laser beams to the first and second targets, respectively, to form a first plume over the first target and a second plume over the second target, the axis of the first plume being substantially parallel to the first surface,of the substrate and the axis of the second plume being substantially parallel to the second surface of the substrate, wherein said first plume contacts the first surface and the second plume contacts the second surface, thereby depositing the first deposition material on the first surface and thereby depositing the second deposition material on the second surface.
According to the present invention, one target is disposed near the front surface (first surface or upper surface) of the substrate and another target is disposed near the back surface (second surface or lower surface) of a substrate, with off-axis geometry. Each of these targets has their own laser beam path to the target. In this arrangement, different laser beam strikes each of the targets, and different "plume" is created over each of the targets, thereby each of these surfaces of the substrate is deposited with different plume. Therefore, thin films with an excellent quality and an uniform thickness distribution can be simultaneously formed on both sides of the substrate. Further, since respective targets and laser beams are used for these surfaces, the deposition rates on the front and the back surfaces can be separately controlled, while it is also possible for the thin films to be formed on both surfaces with the same deposition rate.
Consequently, layers of conductor or high-temperature superconductor can be formed on both upper and lower surfaces of a single substrate, thereby high-frequency devices can be produced with the favorable high-frequency characteristics and the improved reliability.
The present invention will be more fully understood from the detailed description given hereinbelow and the accompanying drawings, which are given by way of illustration only and are not to be considered as limiting the present invention.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will be apparent to those skilled in the art from this detailed description.
These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description, appended claims, and accompanying drawings, where;
FIG. 1 is a perspective view schematically showing a microwave resonator manufactured in accordance with the present invention;
FIGS. 2A, 2B, 2C, 2D, 2E, and 2F are cross-sectional views schematically showing a microwave resonator formed in accordance with the present invention, respectively representing states thereof in successive steps of a manufacturing method in accordance with the present invention;
FIG. 3 is a cross-sectional view showing a laser ablation apparatus which is preferably used for performing a manufacturing method in accordance with the present invention;
FIG. 4 is a system diagram showing an apparatus for measuring a high-frequency characteristic of a device; and
FIG. 5 is an exploded perspective view showing a microwave resonator in accordance with the prior art.
FIG. 3 is a cross-sectional view showing the laser ablation apparatus according to the present invention. In the following, the laser ablation apparatus used in the preferable embodiment according to the present invention will be explained with reference to FIG. 3.
As shown in FIG. 3, a laser ablation apparatus 200 of the illustrated embodiment according to the present invention comprises a cylindrical processing chamber 202. The evacuable chamber 202 is externally defined by a body 204 made of stainless (SUS304) and a lid 206 made of SUS304. The chamber 202 includes a substrate holder 210 for holding a substrate 208 and target holders 214a and 214b for holding targets 212a and 212b. Both targets are made of a target material such as metal oxide. The target material of the first target 212a may be different from the target material of the second target 212b, if desired.
As shown in FIG. 3, the two target holders 214a and 214b are provided with respect to the single substrate holder 210 in the laser ablation processing chamber 202 according to the present invention. The target 212a is positioned in one side (front surface side) of the substrate 208, and the target 212b is positioned in another side (back surface side).
The second target 212b is positioned to be substantially coplanar with the first target 212a, as shown in FIG. 3. The substrate 208 is positioned above a space between the first and second targets, and the substrate 208 is oriented to be substantially perpendicular to the targets. The distance between the substrate 208 and each of the targets 212a and 212b is about 5 to about 10 cm.
As shown in FIG. 3, the chamber 202 includes within the chamber 202 a cylindrical heater 216 which efficiently heats the substrate 208 such that the substrate can have a uniform temperature distribution.
The heater 216 is capable of being controlled so as to adjust the output power to the desired level for the increasing substrate temperature during the deposition due to the change of the optical absorption index of the substrate.
Next, the laser optical system of the laser ablation apparatus 200 will be explained. In this apparatus 200, a laser beam source is disposed outside of the chamber. As shown in FIG. 3, the chamber 202 has entrance windows 220a and 220b through which laser beams pass and enter the chamber 202. The laser beam optical system comprises a laser beam source 222, a half mirror 224, a total reflection mirror 228, and condenser lenses 229a and 229b. Both of the entrance windows 220a and 220b are made of synthetic quartz having a thickness of 10 mm. The laser beam source 222 is equipped with a KrF excimer laser source for emitting a laser having a wavelength of 248 nm. Alternatively, this laser source may be of ArF excimer laser having a wavelength of 193 nm or of XeCl excimer laser having a wavelength of 308 nm.
The laser beam emitted from the laser beam source 222 (indicated by dotted line 230) enters the half mirror 224. The half mirror 224 reflects a part of the laser beam(50% of the total intensity), while transmitting the other part of the laser beam(another 50% of the total intensity). Therefore, the single laser beam 230 entering the half mirror 224 splits into two beams (indicated by dotted lines 232a and 232b), and the two laser beams respectively pass through condenser lenses 229a and 229b and enter the entrance windows 220a and 220b, respectively.
The type of the laser beam system available to the present invention is not limited to the illustrated embodiment shown in FIG. 3. For example, two laser sources may be provided for the two targets. In this manner, deposition rates at the front and the back surfaces of the substrate can separately be controlled, by adjusting each of the laser beam energies of the two laser beam source, respectively.
During striking of the laser beam onto the target surfaces, atoms of metal oxide on the surfaces of targets 212a and 212b are activated and sublimed to form plumes (schematically depicted with dotted curves 234a and 234b), whereby the atoms of the target material are released and reach the substrate 208, thereby being deposited on the substrate surfaces. The plumes 234a and 234b are respectively formed with axes 234c and 234d.
Here, the arrangement of the substrate and the targets is the off-axis oriented arrangement. More specifically, the substrate 208 is disposed so as to substantially parallel to the axes 234c and 234d of plumes, or in other words, the surface of the substrate is oriented so as to form an angle of about -30° (deg.) to +30° (deg.) with respect to the axes 234c and 234d of the plumes. Since a plume is formed with an axis perpendicular to a target surface, the deposition surface of substrate is disposed so as to have an angle ranging from about 60° to about 120° with respect to the target surface.
Since the mirrors 228a and 228b for reflecting laser beams are fixed, the laser beam path are also affixed to reach onto predetermined locations of the targets 212a and 212b, thereby cause non-uniform consumption of the targets. In order to avoid the non-uniform consumption of the targets, the targets are rotated such that the laser can be incident on a certain range of area.
As shown in FIG. 3, the mechanism for rotating targets in the laser ablation apparatus 200 comprises motors 236a and 236b, shafts 238a and 238b, tubes 240a and 240b for holding the shafts, and coupling portions 242a and 242b are provided. An end portion of each of the shafts 238a and 238b on the chamber side and an end portion of each of the target holders 214a and 214b on the chamber wall side are respectively equipped with magnets (not depicted), whereby rotational movements of the shafts 238a and 238b provided by the motors 236a and 236b are transmitted to the target holders 214a and 214b by magnetic connection, respectively. By means of such terminals for introducing magnetic coupling rotation, the targets 212a and 212b are rotated.
Also, in order to uniformly deposit the target material such as metal oxide complex onto the substrate, the laser ablation apparatus includes a mechanism for rotating the substrate.
As shown in FIG. 3, a motor 256 for rotating the substrate holder 210 and a terminal 252 for introducing magnetic coupling are provided.
(Manufacture of Microwave Resonator by Laser Ablation Apparatus Shown in FIGS. 3) In the following Examples 1 to 6, members for a microwave resonator were manufactured while using various metal oxides as target materials and an single crystalline MgO plate as a substrate for depositing target materials. All the Examples 1 through 6 were carried out by using substantially same procedure and materials , except the metal oxides to be deposited.
FIG. 1 is a perspective view showing a member for the microwave resonator manufactured in this example. Here, in order to facilitate representation, FIG. 1 is depicted with exaggeration and, accordingly, does not always correspond to the numerical values in the following explanation. As shown in FIG. 1, a microwave resonator member 10 comprises, on an MgO single crystal plate 12, a circular film 14 and substantially rectangular films 16a and 16b which are made of metal oxide complex, and also comprises, under the MgO 12, a ground plane film 18 which is similarly made of metal oxide. The MgO plate 12, which is a dielectric, has a dimension of: a length of 20 mm, a width of 10 mm, and a thickness of 0.5 mm. The circular film 14 has a dimension of: a diameter of 5 mm and a thickness of 0.5 μm. Each of the substantially rectangular films 16a and 16b has a dimension of: a length of 7 mm, a width of 1 mm, and a thickness of 0.5 μm, while being separated from the circular film 14 by a distance (indicated by arrow 17a or 17b) of 0.5 mm. The ground plane film 18 is formed on the whole lower surface of the MgO single crystal plate 12 with a uniform thickness of 0.5 μm.
FIGS. 2A to 2F are cross-sectional views sequentially showing the steps for manufacturing the microwave resonator in this example. With reference to these drawings, the outline of the method for making the microwave resonator in this example will be explained. First, on the upper and lower surfaces of the dielectric 12 shown in FIG. 2A, oxide films 141 and 181 are simultaneously formed, respectively (FIG. 2B). Then, a photoresist is coated on the whole upper surface of the oxide film 141 so as to form a photoresist layer 20 (FIG. 2C). After being exposed to light by using a mask, the whole laminate is immersed in a developing liquid, whereby a photoresist pattern 201 is formed on the surface of the oxide film (FIG. 2D). Then, the oxide is removed by etching such that only a part of the oxide film that is protected by the pattern 201 is left (FIG. 2E; FIGS. 2E and 2F showing only the cross section of the circular film 14 shown in FIG. 1 without showing that of the rectangular films). Finally, the photoresist pattern 201 is removed so as to accomplish a desired microwave resonator.
In Example 1, the laser ablation apparatus shown in FIG. 3 was used to form thin films of a metal oxide on both front and the back surfaces of the MgO single crystal plate, i.e., dielectric, and then these layers were etched into predetermined patterns so as to manufacture a microwave resonator such as that shown in FIG. 1.
In Example 1, Y1 Ba2 Cu3 O7-X (hereinbelow referred "YBCO") was used as the metal oxide. As the dielectric substrate, a MgO single crystal plate which had a (100) plane and whose both surfaces had been subjected to mirror polishing was used. The single crystal MgO substrate had a dimension of 40 mm×40 mm×0.5 mm. The targets were made of Y1 Ba2 Cu3 O7-X.
(1: Forming of YBCO Thin Film on Both Sides of MgO Single Crystal Substrate (FIG. 2B))
In Examples 1 to 6, while using various metal oxides as target materials and an MgO single crystal plate as a substrate for members, films of the metal oxides were formed on the MgO single crystal plate in the off-axis oriented laser ablation apparatus shown in FIG. 3. Then, in the steps similar to those of Example 1, members for a microwave resonator such as that shown in FIG. 1 were manufactured. Examples 1 to 6 were identical to each other except for their kinds of metal oxides to be deposited.
In Example 1, YBa2 Cu3 O7-X was used as the metal oxide. As the dielectric substrate, a MgO single crystal plate which had a (100) plane and whose both surfaces had been subjected to mirror polishing was used. This MgO single crystal substrate had a size of 40 mm×40 mm×0.5 mm.
Conditions for laser ablation in this example were as follows. First, after the atmosphere within the chamber was reduced to 10-5 Torr, a flow of O2 gas was supplied into the chamber such that the pressure within the chamber was maintained at 400 mTorr. Then, electric power was supplied to the heater and this condition was maintained until the substrate temperature was stabilized at 650° to 700° C. In cases where a thermocouple has been placed near the substrate within the chamber beforehand to measure its temperature under various conditions of internal pressure and electric power, for example, thereby determining calibration curves concerning the electric power to the substrate temperature under the respective conditions, the temperature can be controlled, with a favorable reproducibility, solely based on manipulation of electric power. Then, the targets were rotated at 20 rpm, while the substrate was rotated. Electric power was supplied to the laser source (KrF laser having a wavelength of 248 nm) so as to make it generate a laser with a laser output of about 5 W. At this time, the frequency of the laser pulse was 5 Hz, while each pulse had a laser energy of 0.5 J/pulse.
Thus emitted laser impinged on the half mirror. The two lasers split within the half mirror impinged on the targets disposed within the chamber respectively through the entrance windows whose surfaces had been coated with non-reflective coatings. In this example, each target was formed as a disk having a diameter of 20 mm, while the laser irradiation area on the target surface was 10 mm2 (irradiation area of 2 mm×5 mm). The laser energy density of the split single laser was 1.5 to 2.0 J/cm2 after having been partially lost as the laser passed through the half mirror or the total reflection mirror. Accordingly, the laser energy was 150 to 200 mJ.
In this example, the respective targets were placed at off-axis positions, while separate lasers were incident thereon. In this example, the angle at which the respective lasers (depicted with dotted lines 232a and 232b) were incident on the surfaces of the targets 212a and 212b was 90° (deg). Also, in order to prevent the targets from being locally consumed due to the fact that the laser impinged on a single point of the target surface, the targets were rotated while the laser was made incident on a position dislocated from the rotational axis. As a result, the laser was incident on a wide area on the target surface.
Also, the substrate was rotated in order to uniformly form the YBCO film on the whole surface thereof. As shown in FIG. 3, on the surfaces of the targets 212a and 212b irradiated with the laser beams, YBCO constituting the target surface is sublimed so as to form plumes such as those depicted by dotted curves 234a and 234b. The amount of vapor deposition is the largest in the proximity of the axis or center of the plume and gradually decreases as the distance from the axis increases. Accordingly, if the substrate is fixed, there will be a certain distribution in the thickness of the thin film deposited on the surface. In order to avoid such problem, the substrate was rotated in this example so as to form thin layers without varying film thickness across the entire surface.
More specifically, the substrate in this example is arranged such that the substrate surface has an angle of about -30° (deg.) to about +30° (deg.) with respect to the axes 234c and 234d of the plumes.
The two lasers 232a and 232b shown in FIG. 3 in this example are derived from the single laser 230 which splits by the half mirror 224. Accordingly, these two laser beams can have the same laser energy. Accordingly, energies formed by the respective lasers input to the targets can be made identical to each other. When both front and the back surfaces of the substrate are equally heated by a heater and the distances between the substrate and the respective targets are set equally, an oxide high-temperature superconductor can be easily formed on both front and the back surfaces of the substrate with the same film quality and the same deposition rate. The distance between the surface of each of the target and the center of the substrate was 100 mm, respectively.
At the target surface on which the laser is incident, each atom of Y, Ba, Cu, and O is sublimed and, as an atom, reaches the substrate so as to be deposited thereon. In this manner, the depositing operation was performed about 17 minutes so as to deposit a thin layer of YBCO having a thickness of about 0.5 μm. In this example, based on the thickness of thus obtained YBCO film and the operation time, the average deposition rate was about 1 angstrom/pulse.
The conductivity of the thin film formed on the MgO substrate in this manner was measured as explained in the following. One of the substrates on which the thin films had been formed was taken out for measuring the conductivity of the thin film and then a bridge of 20 μm×20 μm was formed on the thin film on one surface thereof by photolithography and etching. Then, under various temperature conditions, a general four point probe method was used to measure the voltage generated at both sides of the bridge, thereby yielding a resistance value. Thus, the temperature at which the generated voltage becomes not higher than 1 μV was defined as critical temperature for superconductivity (Tc). In the thin film of this embodiment, Tc was 90 K. Then, at 77 K, the current supplied to the bridge was gradually increased. The current at which a resistance was generated was defined as critical current (Ic). This Ic was divided by the current-passing cross-sectional area of the bridge so as to yield critical current density (Jc). The critical current density of the YBCO thin film manufactured in this example was 3,000,000 A/cm2.
Also, a part of thus obtained YBCO thin film was removed and the resulting step formed at the boundary of the film and substrate was measured by a contact-type surface roughness tester. Similar measurement was performed on the whole surface of the film to determine the thickness distribution of the film. The fluctuation in thickness of the thin film formed in this example was within the range of +/-5% for each of the front and the back surfaces.
(2: Forming of Photoresist Pattern (FIGS. 2C and 2D))
On one surface of the YBCO film formed as mentioned above, a photoresist pattern was formed by a well-known photoresist.
As a photoresist material, without being restricted in particular, commercially available resist materials for silicon semiconductor can be used. For example, as a positive resist material, general positive resist materials such as OFPR-2 (manufactured by Tokyo Ohka Kogyo Co.) and AZ111 (manufactured by Hoechst AG) can be used. Also, as a negative resist material, JSR CIR-712 (manufactured by Japan Synthetic Rubber Co.) or the like can be used.
By a method widely used for the mass production step in the semiconductor manufacturing process, a positive photoresist material was coated and then exposed to light by using a mask, whereby the resist material having a pattern of the circular thin film 14 and substantially rectangular thin films 16a and 16b shown in FIG. 1 was formed on the YBCO thin film.
(3: Etching of YBCO (FIG. 2E))
The YBCO film was etched out leaving the portion protected by the photoresist formed as mentioned above. For the etching, ion milling widely used for the mass production step in the semiconductor manufacturing process was used.
(4: Removal of Resist Material (FIG. 2F))
Finally, the remaining resist material was removed by acetone, thereby accomplishing a microwave resonator member such as that shown in FIG. 1.
(5: Measurement of High-Frequency Characteristic of Microwave Resonator Member)
The high-frequency characteristic of thus formed microwave resonator member was evaluated. This microwave resonator member had a configuration in which an oxide high-temperature superconductor was formed on both front surface (where the circular thin film is formed) and the back surface of the dielectric. Accordingly, a microwave input into this resonator is guided in the horizontal direction, which is directed from one rectangular thin film to the other rectangular thin film through the circular thin film, while being resonated.
The high-frequency characteristic was evaluated as follows. Namely, after the resonator was equilibrated at a temperature of 77 K within a cryostat, a microwave of 5 GHz was input thereto and the resulting Q value was determined. For measuring the Q value, a network analyzer was used.
FIG. 4 is a system diagram of an apparatus used for evaluating the high-frequency characteristic of the microwave resonator manufactured in this example. As shown in FIG. 4, a high-frequency characteristic measuring apparatus 300 comprises a cryostat 304, which contains a sample (microwave resonator) 302 so as to equilibrate it at a predetermined temperature, and a network analyzer 306. The cryostat 304 is equipped with a cooler 308 and a temperature controller 310. The range of temperature which can be controlled by the temperature controller 310 is 30 to 300 K. The network analyzer 306 is connected to a signal source 312 so as to control the latter. The network analyzer 306 and the temperature controller 310 are collectively controlled by a system controller 314. The network analyzer 306 used in this example was the HP8515B (manufactured by Hewlett-Packard Co).
As shown in FIG. 4, the resonator 302 manufactured in this example was set within the cryostat 304 and cooled to a temperature of 77 K. Then, a high-frequency signal of 5 GHz was generated at the signal source 312 and introduced into the network analyzer 306. This 5-GHz high-frequency signal was input into the sample 302 within the cryostat 304 by the network analyzer 306, while the response therefrom was fed back to the network analyzer 306.
The Q value of the microwave resonator manufactured in this example was 50,000 at 77 K. Accordingly, it was confirmed that the microwave resonator using the oxide high-temperature superconductor manufactured in this example had a favorable frequency characteristic.
In a manner similar to Example 1, TlBa2 CaCu2 OX was used as a deposition material for a target so as to deposit TlBa2 CaCu2 OX on an MgO substrate, thereby forming a microwave resonator, whose high-frequency characteristic was then evaluated.
Thus obtained TlBa2 CaCu2 OX thin film exhibited a Tc of 95 K and a Jc of 1,000,000 A/cm2 at 77 K. Also, the Q value of thus manufactured resonator was 45,000.
Tl2 Ba2 CaCu2 OX was used as a deposition material for a target so as to deposit Tl2 Ba2 CaCu2 OX on an MgO substrate, thereby forming a microwave resonator, whose high-frequency characteristic was then evaluated.
Thus obtained Tl2 Ba2 CaCu2 OX thin film exhibited a Tc of 100 K and a Jc of 1,200,000 A/cm2 at 77 K. Also, the Q value of thus manufactured resonator was 55,000.
Tl2 Ba2 CaCu2 OX was used as a deposition material for a target so as to deposit Tl2 Ba2 Ca2 Cu3 OX on an MgO substrate, thereby forming a microwave resonator, whose high-frequency characteristic was then evaluated.
Thus obtained Tl2 Ba2 Ca2 Cu3 OX thin film exhibited a Tc of 115 K and a Jc of 3,000,000 A/cm2 at 77 K. Also, the Q value of thus manufactured resonator was 58,000.
Bi2 Sr2 CaCu2 OX was used as a deposition material for a target so as to deposit Bi2 Sr2 CaCu2 OX on an MgO substrate, thereby forming a microwave resonator, whose high-frequency characteristic was then evaluated.
Thus obtained Bi2 Sr2 CaCu2 OX thin film exhibited a Tc of 85 K and a Jc of 800,000 A/cm2 at 77 K. Also, the Q value of thus manufactured resonator was 37,000.
Bi2 Sr2 Ca2 Cu3 OX was used as a deposition material for a target so as to deposit Bi2 Sr2 Ca2 Cu3 OX on a MgO substrate, thereby forming a microwave resonator, whose high-frequency characteristic was then evaluated.
Thus obtained Bi2 Sr,Ca2 Cu3 OX thin film exhibited a Tc of 90 K and a Jc of 900,000 A/cm2 at 77 K. Also, the Q value of the thus manufactured resonator was 42,000.
It should be understood that the preferred embodiments of the invention are given by way of illustration only. From the invention thus described, it will be obvious that the invention may be varied in many ways. For example, as the dielectric substrate, other than MgO, such materials as LaAlO3 having (100) plane, sapphire having R plane (Al2 O3), and SrTiO3 may be used. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended for inclusion within the scope of the following claims.
The basic Japanese Application No. 074422/1995 (75-074422) filed on Mar. 7, 1995 is hereby incorporated by reference.
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|U.S. Classification||427/596, 427/597, 427/561, 219/121.76, 505/474, 219/121.85|
|International Classification||C01G3/00, H01P11/00, C30B25/10, H01P7/08, C01G1/00, C23C14/28, H01L39/24|
|Cooperative Classification||H01L39/2448, C23C14/28|
|European Classification||C23C14/28, H01L39/24J2H|
|Mar 1, 1996||AS||Assignment|
Owner name: SUMITOMO ELECTRIC INDUSTRIES, LTD., JAPAN
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:ITOZAKI, HIDEO;NAGAISHI, TATSUOKI;REEL/FRAME:007890/0523
Effective date: 19960221
|Apr 30, 2002||REMI||Maintenance fee reminder mailed|
|Oct 15, 2002||LAPS||Lapse for failure to pay maintenance fees|
|Dec 10, 2002||FP||Expired due to failure to pay maintenance fee|
Effective date: 20021013


The Department of Biology is equipped with several state-of-the-art imaging microscopes including the Carl Zeiss LSM 710 NLO Laser Scanning Confocal/Multiphoton Microscope. The confocal microscope was obtained through a CFI-LOF
(Canadian Foundation for Innovation –Leader’s Opportunity Fund) award to Drs. Craig Hawryshyn, Ian Chin-Sang and Paul Young. The LSM710 NLO confocal microscope is ideal for the most demanding microscopy applications and allows the simultaneous use of multiple fluorophores. Users can capture high-resolution images of fluorescent structures in living animals and thick tissue specimens. The high signal-to-noise ratio provided by the system ensures brilliant imaging of cellular and sub-cellular structures. The system includes a full suite of software to drive experiments in imaging, 3D reconstruction, timelapse, FRET and FRAP and will support a wide range of applications. Confocal/multi-photon microscopy is the gold standard for fluorescent imaging and the microscopy facility is available for departmental use.
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Independent assessment of Microwave Radiometer measurements in coastal zones using tropospheric delays from GNSS
Event: 2017 Ocean Surface Topography Science Team Meeting
Session: Advances in coastal altimetry: measurement techniques, science applications and synergy with in situ and models
Presentation type: Type Poster
Contribution: PDF file
Zenith tropospheric delays (ZTD) from Global Navigation Satellite Systems (GNSS) stations are used in order to assess the MWR measurements in coastal zones, where some of these observations become invalid due to land contamination. This coastal assessment is performed for eight altimetry missions: the so-called reference missions (TOPEX/Poseidon, Jason-1 and Jason-2), the three ESA missions (ERS-1, ERS-2 and ENVISAT), Geosat Follow-On and SARAL/AltiKa.
Firstly, ZTD are computed for a set of 60 GNSS stations with a good spatial and temporal distribution (ZTD UPorto) using the GAMIT software and state-of-the-art methodologies. These ZTD are further converted into zenith wet delays (WTC equivalent) by subtracting the zenith hydrostatic delay estimated from sea level pressure from the ERA Interim model. ZTD provided by international networks, such as the International GNSS Service (IGS) and EUREF Permanent Network (EPN) are compared with ZTD UPorto, showing that ZTD can be determined with an accuracy of a few millimeters, at the station location. However, jumps are detected in ZTD from a few IGS stations. The influence of network geometry on tropospheric parameters estimation is demonstrated.
Secondly, the analysis of the root mean square of the differences between MWR measurements and ZWD UPorto, function of distance from coast, shows the effect of land contamination and the distance from coast where this contamination is minimum. This distance from coast is different for the several altimetric missions, due to their different footprint size and algorithms used to retrieve the WTC from MWR measurements.
The coastal assessment shows also the ability of the GNSS-derived Path Delay Plus (GPD+) algorithm from University of Porto to remove this contamination and to improve the WTC retrieval all over and in particular in the coastal zones.
Aiming at inspecting the stability of the MWR measurements, the time evolution of the same WTC differences is analyzed. In spite of the fact that GNSS-derived and MWR-derived WTC are not collocated measurements, these results show that the former are a useful independent source to inspect the land effects on MWR observations and to monitor the stability of these instruments, thus contributing to the retrieval of precise water surface heights from satellite altimetry.


By using High-Voltage Ion Implantation, PREMA can offer several types of photodiodes with different spectral sensitivities. Unless stated otherwise, photodiodes are type I.
Because all in semiconductor industry common fabrication techniques are available, photodiodes can be closely packed next to each other. (Arrays of photodiodes)
For applications using higher frequencies, a special type of photodiodes with reduced capacitances (< 25 pF/mm²) is available. Very low dark current with less than 100 pA at reverse voltages of 10 V can be achieved.


Monitoring Volcano Ground Deformation with Electronic Distance Meters
Measuring the distance between benchmarks placed on a volcano tens to thousands of meters apart can sometimes pinpoint where and when magma is rising toward the surface. Rising magma will sometimes push overlying rocks upward or shove them aside. In either case, one part of the volcano may actually move horizontally relative to another part from as little as a few millimeters to as much as several tens of meters. The challenge in measuring such changes with an electronic distance meter is putting benchmarks in the right places and making frequent measurements between pairs of benchmarks.
What is an electronic distance meter?
An electronic distance meter is an instrument that both sends and receives an electromagnetic signal. Depending on the distance between the EDM and reflector, the wavelength of the returned signal will be out of phase with the transmitted signal. The instrument compares the phase of the transmitted and received signals and measures the phase difference electronically. There is a wide range of EDM capabilities in range and precision, but for volcano monitoring purposes, short-range (less than 10 km) to medium-range (less than 50 km) EDM's are typically used. Short-range EDM's transmit and receive the near visible infrared part of the electromagnetic spectrum for measuring distances with an accuracy of about 5 mm.


Participants: Esteban Maestre, Hossein Mansour, Vincent Fréour and Gary Scavone
Period: 2011 - ongoing
Despite having existed in their present form (for the most part) for over 400 years, bowed-string instruments remain the subject of active research in the musical acoustics community. While their general behaviour is reasonably well understood, measurable properties that can be used to distinguish instruments of very different perceived qualities have remained illusive. The goal of this research is to build numerical models of increasing refinement, parameterized by measurements when possible, to explore and test which physical characteristics play a significant role in defining an instrument’s “playability” and sound.
In collaboration with Dr. James Woodhouse at Cambridge University, Ph.D. student Hossein Mansour developed a variety of new model features, including the frequency-dependent behavior of the strings, modal properties of an actual body as determined from measurements, dual-polarization of the strings, longitudinal vibrations of the bow-hair, bow-stick properties, and sympathetic vibrations of the freely vibrating strings. He also derived a more robust version of a famous predictive equation for violin playability. The model was then used as a quasi-experimental tool to systematically investigate the effect of each detail on the timbre and playability of the instrument. This research represents important contributions to our understanding of bowed-string instruments, with potential applications for luthiers, string manufacturers, players, and researchers working to synthesize the sound of bowed strings.
Since 2012, we have engaged in a research collaboration with Dr. Esteban Maestre and Dr. Julius Smith (Stanford University) to investigate the design of violin and guitar body filters, parameterized from measurements, for sound synthesis models. This research has included: modal decomposition of measured driving-point admittances obtained by means of a novel frequency-domain algorithm for optimization of digital filters in parallel form; passive modeling of radiativity and admittance by projection of measurements over a common modal basis, and an efficient implementation of bridge reflectance and sound radiativity filters from a single bank of shared resonant filters. The results make it possible to synthesize in real time the sound of a specific violin or guitar, with many possible commercial applications. For example, this technology could be used to virtually audition, via an online interface, a set of instruments for sale in a shop.
A recent collaboration with several researchers at Stanford and the Politecnico di Milano is focusing on the virtual restoration and resynthesis of a historically important violin, the 1716 “Messiah” by Stradivarius, which has never been played because of a crack in its top plate.
We began a six-month research project in 2013 with Godin Guitars, a Quebec company that manufactures approximately 50,000 acoustic and 20,000 electric guitars each year. The project, funded by an NSERC Engage grant, investigated the use of measurements to allow the manufacturer to better categorize subsets of instruments according to sounding characteristics. The study benefitted from the availability of a large set (over 30) of nominally identical steel-string guitars, a truly unique asset among studies of this kind. One goal of the work was to find features of guitar admittances that could be used to automatically distinguish them according to three classifications (bassy, mid-even and treble) suggested by the manufacturer. A second goal was to investigate whether experienced guitarists agree with those classifications.
Results of this work, which was conducted by a team of three Ph.D. candidates (Hossein Mansour, Vincent Fréour and Charalampos Saitis), showed very low agreement across guitarists with the manufacturer-provided classifications. However, analysis of the measurements indicated that the guitars categorized as bassy had a lower breathing mode frequency (which can be related to the stiffness-to-weight ratio of the bodies). We also found that averaged mobilities in the 600–2000 Hz range could distinguish the mid-even and treble instruments, though results with new instruments outside the original analysis pool did not confirm this finding. The results are significant because they represent one of the few examples in string instrument research of a clear correspondence between a physical property derived from a measured body response and a perceptual characteristic (bassy-ness) of the resulting sound.


|SNR||SNR or S/N (Signal-to-Noise Ratio)
In communications, signal-to-noise ratio is a measure of signal strength relative to background noise (measured as signal level divided by noise). The ratio is usually measured in decibels (dB).
Higher SNR numbers repesent cleaner signals, with less noise. Decreasing noise, and/or increasing signal increases/improves the SNR value.


The video is recorded from an actual AF ablation procedure using the CARTO-3 mapping system. We use the 3D mapping system to move our catheters without the use of X-rays. We can see exactly how much force is generated with at the tip of our ablation catheter and which direction we are moving (arrow).
1) An ablation catheter is used to cauterise the tissue around the pulmonary veins (PV). Ablation lesions (red dots) are delivered to electrically isolate the PVs from the rest of the LA.
2) A circular mapping catheter is used to map the electrical activity inside the pulmonary veins.
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Self-adaptive dual-metal-site pairs in metal-organic frameworks for selective CO2 photoreduction to CH4
Release time：2021-09-09 Views：101
Jian Li1,3, Hongliang Huang 1,3, Wenjuan Xue1,3, Kang Sun2,3, Xiaohui Song1 , Chunrui Wu1 , Lei Nie 1 , Yang Li1 , Chengyuan Liu2 , Yang Pan2 , Hai-Long Jiang 2 ✉, Donghai Mei 1 ✉ and Chongli Zhong 1 ✉
Solar-light-driven reduction of CO2-to-CH4 is a complex process involving multiple elementary reactions and various by-products. Achieving high CH4 activity and selectivity therefore remain a significant challenge. Here we show a bioinspired photocatalyst with flexible dual-metal-site pairs (DMSPs), which exhibit dynamic self-adaptive behaviour to fit mutative C1 intermediates, achieving CO2-to-CH4 photoreduction. The Cu and Ni DMSPs in their respective single-site forms under flexible microenvironment are incorporated into a metal-organic framework (MOF) to afford MOF-808-CuNi. This dramatically boosts CH4 selectivity up to 99.4% (electron basis) and 97.5% (product basis), and results in a high production rate of 158.7 μmol g−1 h−1 with a sacrificial reagent. Density functional theory calculations reveal that the flexible self-adaptive DMSPs can stabilize various C1 intermediates in multistep elementary reactions, leading to highly selective CO2-to-CH4 process. This work demonstrates that efficient and selective heterogeneous catalytic processes can be achieved by stabilizing reaction intermediates via the self-adaptive DMSP mechanism.
Photocatalytic CO2 reduction measurements. Here, 25mg of photocatalyst powder and 50mg (molar concentration 1.3mM) of [Ru(bpy)3]Cl2•6H2O were mixed in a 50-ml solution containing 30ml of acetonitrile, 10ml of TEOA and 10ml of H2O in a 250-ml quartz reaction cell. The CO2 (purity >99.999%) was purged into this reaction cell for 0.5h to eliminate the dissolved oxygen. Before illumination, the reactor was installed to CEL-SPH2N system (Beijing China Education Au-light Co., Ltd) equipped with a 300-W Xe lamp with the 420-nm cutoff filter (420nm<λ<760nm). On degassing,the system was filled with CO2 (purity >99.999%) to 1 atm. For photocatalytic CO and HCOOH reduction measurements, 10ml of CO (99.999%) or 1ml of liquid HCOOH was injected into photocatalytic system. Subsequently, the Ar as the packed gas was purged into the system to reach atmospheric pressure. Gas chromatography (Agilent 7890B) was applied to analysed gaseous products by the detectors of a thermal conductivity detector and a flame ionization detector using Ar as the carrier gas. The HCOOH in the liquid phase was analysed using ion chromatography (Thermo ICS-5000). The possible alcohol products were detected by a liquid chromatogram (Waterse 2695), and no related signals could be observed. The catalytic results were repeated three times with three batches of catalysts to give more reliable data. Gas chromatography– mass spectrometry (Bruker solanX 70 FT-MS) was applied to analyse the isotope labelled products using 13CO2 as the feed gas. The light intensity data were measured using a PM100D optical power meter (Thorlabs) equipped with a S425C detector (Supplementary Table 9). The heterogeneity test was performed by removing the catalyst from the reaction medium at 6h by centrifugation49.
Download:Nature Catalysis 2021, 4, 719–729 MOF-808-CuNi CO2RR.pdf


PAH, BTEX, Mineral oil
Location: Ghent, Belgium
The Interreg’s RESANAT project promotes nature-based remediation techniques for residual soil contamination. The project concerns a full scale field test of a reactive mat (natural catch) in an urban canal threatened by groundwater contamination. The contamination originates from former industrial activities on the bank. The contamination migrates with the groundwater into the surface water, posing spreading and ecological risks. Measurement of groundwater and mass flux allows to identify flow patterns and determine mass discharge to the surface water. Based on the results the most appropriate remediation technique and materials are selected. The results helped our partner to dimension a barrier, both the needed hydraulic conductivity and its capacity to filter contaminant influx.
In 2019, restoration of the drainage capacity of the canal was needed, and the sediment was dredged. By dredging the canal the drainage capacity increased and adsorption of contamination decreased. It led to an increase of contamination in the surface water. The horizontal flux of groundwater and contamination was measured before and after dredging. Horizontal flux samplers were installed on 2 depths, in existing wells in the bank of the canal. Additional vertical flux, upwards and downwards were measured after dredging in the sediment of the canal. In a first stage digital flux measurements of groundwater were performed in 30 locations. The results are available in real time. Based on these measurements 10 locations were selected to install samplers to measure vertical flux over a longer period. The flux measurements provided useful information about the distribution of the inflow over the length of the canal and the effect of dilution and degradation downstream and allowed to refine the conceptual site model.
"Flux measurements created new insights of the distribution inflow of the contamination to the canal, the presence of hot spots, the degradation and dilution occuring downstream." - Tobias Praamstra (TAUW)
How to measure the inflow of contamination to the canal and nearby urban area:
Groundwater flow increased due to dredging of the canal. By traditional sampling only concentration in the groundwater is measured.
The groundwater and mass flux before dredging was rather low. Flux measurements showed an significant increase of the groundwater flux after dredging. The BTEXN flux measured in the wells in the banks increased till 15 times in comparison with the flux before dredging. The PAH flux increased till 3times. After dredging an additional flux of mineral oil is measured. The mineral oil compounds were mobilised after the dredging.
In the sediment of the canal the flux was dominantly upward, from groundwater to surface water. The flux varied strongly because of the heterogeneity of the sediment and characteristics of the canal. The use of passive mass flux sampling in combination with real time continuous flow velocity and direction measurement with digital sensors allowed to characterize exchanges at the interface between groundwater and surface water and to create illuminating insights in the dynamics influencing the water quality. The data led to an effective remediation concept.
Based on the groundwater and mass flux data it became clear where targeted action was needed. With the data it was possible to divide the trajectory into three segments, with each its own dimensions for developing a remediation concept based on the natural characteristics, i.e. drainage capacity, a green adsorbent and biological activity to cope with the inflow of contamination and improve water quality.
In addition, a monitoring plan has been developed including assessments of the effectiveness and progress with flux measurements.


Thermal power plants
Turbo-charged with sCO2 turbines
In the Carbosola research project, teams of scientists develop turbines that run on supercritical carbon dioxide.
Carbon dioxide (CO2) is known as a harmful greenhouse gas. Supercritical carbon dioxide (sCO2), on the other hand, can actually do the environment good - by being used as a heat transfer medium in power plant processes instead of steam. There, it could produce more power in a closed circuit under certain conditions in much smaller turbines than before. This saves costs and space, as the researchers in the Carbosola project were able to demonstrate. In concrete terms, the technology could be used on site at industrial companies such as steelworks or glass foundries, for example. The companies could channel their exhaust heat with high process-related temperatures from manufacturing directly on their factory premises into a small power plant with sCO2 turbines and produce electricity there.
Producing electricity 25 per cent cheaper with sCO2 turbines than with conventional turbines
This technology is still a vision of the future. However, the Carbosola research project and the resulting findings should enable the entry into this innovative technology in Germany. The German Federal Ministry for Economic Affairs and Energy is therefore funding the research project with 2.2 million euros. Initial results from the Carbosola research project show the huge potential for financial savings: "Our numerical investigations have shown that power generation costs with supercritical CO2 can be up to 25 per cent cheaper compared to production from a steam-driven power plant process", reports Carbosola project manager Dr Stefan Glos from Siemens Energy Global. Together with scientists from the Technical University of Dresden, the German Aerospace Center (DLR) and the Helmholz Center Dresden Rossendorf, Siemens is currently working on further optimising the turbine components and operating processes in digital models and laboratory experiments.
Supercritical CO2: not critical, but super
What makes supercritical CO2 so attractive for a power plant process? At 31 degrees Celsius and 74 bar, the carbon dioxide enters a state in which its weight corresponds to that of a liquid, but it can flow as easily as a gas. In this supercritical state, CO2 is extremely powerful: Its physical density is higher than steam while having good flow properties, similar to those of steam. This means that more power can be generated in turbines that are up to five times smaller. As this method is a closed cycle process, no carbon dioxide is released into the environment. In addition, exhaust heat from industrial processes is put to good use.
Further research is needed to ensure that the advantages shown can also be realised in practice. For example, supercritical carbon dioxide behaves differently in the turbine than steam. The special physical properties of the fluid mean that the turbines are sometimes subjected to greater stress than conventional turbines operated with steam. The components therefore have to be further developed and their materials adapted.
The technology is being tested in a test system that is unique in Europe
In addition to the design of a potential large-scale application, in recent months the individual components of a test system were configured and their interaction optimised by means of simulation. This test system will now be built over the next few weeks on the premises of the Helmholz Centre Dresden-Rossendorf, where the components and processes will be tested on a larger scale for their practicability. This will create an infrastructure that achieves process parameters that are unparalleled in Europe and enables investigations, for example on flow behaviour and heat exchange, but also on open material questions and effective operating strategies.


Appsfactory and Kuntze Instruments GmbH implement an Internet of Things App for more efficient control and measurement of water values
Kuntze Instruments GmbH has been producing high-quality water analysis technologies for 75 years. The company is mainly specialized in the measurement of disinfectants, pH values, redox potentials and other parameters and, in addition to sensors, also produces measuring instruments and complete measuring systems. In recent months, the frontend of the Kuntze Sensor Monitoring App for iOS and Android has been created in collaboration with Appsfactory. Using the application, logging and analysis of water are largely automated.
The app is connected to CloudConnect, Kuntze’s software-as-a-service platform. A highlight of the Internet of Things (IoT) solution is the control of the workflow with the possibility to automatically send a notification to the operator of, for example, swimming pools when certain measured values are exceeded.It is also possible to receive operational optimization recommendations directly from Kuntze Instruments GmbH. Special measured values such as chlorine, the pH value and the temperature can be read live in the “My Facilities” function area. This keeps the relevant employees and users of the app informed in real time so they can exert corrections if necessary. With a comprehensive and clear presentation of all relevant values and their permanent availability to those in charge, the Kuntze IoT app makes a crucial contribution to improving the environment.


Pot Top Sensor (NTC) Sensor Probe
|FOB Price:||US $0.65 / Piece|
|Min. Order:||5,000 Pieces|
|Min. Order||FOB Price|
|5,000 Pieces||US $0.65/ Piece|
- Model NO.: NTC sensor: 14000040
- Transport Package: Carton
- Trademark: CDM
- Origin: China
|Conventional resistance value||R25=100KΩR100=6.7KΩB25/50=3950K||The resistance value could be changed as required by customer.|
|Applicable temperature scope;||-30ºC-105ºC/-30ºC-125ºC/-30ºC-250ºC|
|Insulation and voltage resistance||AC1500V/5mA/60Sec/AC2000V/5mA/3Sec|
AC1500V/5mA/60Sec or AC2000V/5mA/3Sec
|Thermal response time||τ(63.2%)≤25SecMIN≤15Sec||Conventional structure: 25Sec; special structure: 8Sec|
|Reliability requirements||See product specification|
A. Stable performance and long-term operation.
B. High accuracy of resistance and B values, good consistency and interchangeability
C. High sensitivity and fast response speed.
D Able to be packed as per installation conditions so as to easy for users to install.
E High accuracy of temperature measurement.
Be applied to temperature measurement and control for electric cooker, pressure cooker and others.
Products RoHS compliant materials meet REACH regulations


In hard waters, high cycle operation risks mineral scale formation. Operating a cooling system at lower cycles reduces the risk of scale formation, but increases operating costs. Basing the concentration ratio set-point on average or bulk water conditions risks missing localized high stress conditions. The result: scaling and loss of heat exchange capacity in critical processes. Recent advances in quartz crystal microbalance technology provide valuable insight into the effects of temperature, water chemistry and operational changes. By measuring the formation of scale, in situ, at various, pre-selected temperatures, the actual scale forming tendencies of a water can be quantified in terms of deposit weight. This paper discusses quartz crystal microbalance technology and its use. Data from field evaluations will be presented.
10-20: A Novel Deposit Monitoring Technique for Industrial Cooling Water And
Daniel M. Cicero, Nalco Company