In this paper, we try to establish a power law for contact resistance versus force R_c = K_cF_c^-n , and we determine via experimental measurements and theoretical calculations, the constants n and K_c in the force range (1 mN-4 N) for bulk metal (Ag, Au, Pd, Ni) used in various applications (microswitches, connectors). The main experimental results of contact resistance are the occurrence of two decrease domains versus progressive load indentation. The first regime corresponds to the earlier touch of the coupon by the probe at force < 0.1 N. This elastic regime evolves to a plastic regime for medium force > 0.1 N. At the transition the exponent value n changes from 0.33 to 0.5 and induce K_c value increasing. Theoretical and computational approaches applied to the elasto-plastic model, confirm the occurrence of these two regimes. Although the calculated values of n are in good agreement with experimental values, some discrepancy between measured and calculated K_c values take place.

In this paper, a Micro-Step-Separating System is realized for investigating phenomena of initial state of separating contacts. This system can control the contact separation in a discrete way with about 0.5 µm step. By using this system, we observed a relationship between contact voltage and contact separation gap. Ag contacts were observed. The observation showed that the contact voltage rose up and then fell down to the stable voltage at each step separation. From this observation, we expect to elucidate the contact bridge phenomena with more sophisticated way because we can approach them under the thermal equilibrium condition.

The effect of the silicone vapor on the reliability of the micro-motor was examined. Adsorbed silicone was decomposed to SiO₂ by heating due to the discharge between brush and commutator surface. It was found that the operation time until the failure was extremely shortened by the formation of SiO₂. The existence of the maximum operation time until the failure was found as depending on the number of revolution. For the higher revolution, many amounts of SiO₂ accumulated by the decomposition of the silicone shorten the operation time. For lower revolution, as the torque of the motor reduces, the operation time also shortens. Therefore, the maximum operation time exists for optimum revolution.

Sliding contact behavior is important in the mechanism of collecting current. In this study, the effect of ambient gas including an inert gas on surface film formation and on the contact voltage drop was examined, changing the atmosphere from low pressure to atmospheric pressure. Furthermore, the sliding surface state was observed using SEM, EDX and XPS analyzers after the test operation. As a result, at the sliding contact in an inert gaseous environment (nitrogen and argon), it was confirmed that the contact voltage drop tends to increase. However, it was clarified that any chemically generated surface film is difficult to detect in the inert gas environment by qualitative analysis. On the basis of these results, we suggest the existence of physically adsorbed surface film. The relationship between inert gases and sliding contact phenomena is discussed.

In recent years, sliding electric contacts came to be often used under very severe conditions such as high temperature, extremely low temperature, high vacuum, etc. Conventionally, solid lubricants having excellent properties in lubricating performance are generally used compositely with a metal of high electric conductivity, because of their high electrical resistivity. In the present study, we proved that more excellent sliding electrical contacts can be produced with a design made by controlling the distribution on contact surface of a solid lubricant having excellent lubricating performance and of a metal with high electric conductivity through expansion of Greenwood's theory.

A LiNbO₃ piezoelectric actuator controls the Au-Au contact gap. The control accuracy of the actuator is within the sub-micron range. Contact voltage, contact current, displacement of electrodes and driving voltage of the actuator were continuously and synchronously recorded by an A/D converter and send to a computer. The measured oscillograph data for 1500 contact operation were processed by the computer. Factors of discharge and bridge phenomena were derived at a contact operation. The delay time between displacement and driving signal of the actuator increased when one side of electric contact were vibrated. The resonance was seen in the actuator, and the dependency to the current and the amplitude was seen.

This paper presents a review of volumetric erosion studies applied to electrical contacts. The numerical methods presented are generic and could equally be applied to a number of areas where surfaces have been eroded or damaged. Equally there is no scale limitation of the surfaces to which the numerical methods can be applied. The paper starts with an introduction of the issues associated with the measurement of contact erosion, and then presents a summary of various hardware system for making 3D measurements of surfaces such as electrical contacts. This is followed by a review of the generic form fitting methods and also volume calculation methods. The paper concludes with a review of results taken from a test system for contact studies and from contact samples taken from commercial relays.

The interrupting characteristics of low voltage current limiting circuit breakers have directly relationship with the magnitude and distribution of magnetic field produced by contact system and splitter plates. In order to analyze the influence of configuration of contact system on current limiting characteristics, 3D magnetic field of arc chamber (including contact system, arc, splitter plates) is calculated. Furthermore, the electromagnetic repulsion force of movable contact is also calculated. The results can be used to improve configuration of arc quenching chamber. The cooperation between operating mechanism and electromagnetic repulsion force is also analyzed in this paper.

Arc duration of silver contacts was measured with fixed short gap under the condition of different constant gaps and different constant currents, which are close to the minimum arc current of the contact material. The results indicated that the arc occurred even at the current less than the minimum arc current. The arc duration varies in different operations at the same testing condition and it distributes exponentially in the time range up to 100 microseconds. The time constant τ and the extinction rate λ of the distribution were calculated, and related to the arc current. It was assured by silver electrode arc that, even below the so-called minimum arc current, arc ignition may occur but, in this case, the arc duration is momentary, and, as the arc current decreases, the arc extinction rate becomes large.

An experimental equation of V-I characteristics of breaking arc was investigated in the air at atmospheric pressure. Material of the contact pair is Ag, Au, Cu and Ni. Supply voltage is set to 42, 48 and 54 V. The electrical resistance of experimental circuit is 5 Ω. The time evolutions of arc voltage, arc current and gap length were measured, simultaneously. V-I characteristics were obtained from those measured values. The dependence of the arc voltage on the gap length was represented by an approximate formula as a straight line in order to obtain the experimental equation. And the dependence of the strength of electric field of arc column on the supply voltage was approximated to a straight line. Using these approximate formulae, the experimental equation of the dependence of the arc voltage on the arc current was obtained with the gap length as a parameter. It was shown that the experimental equation agreed with experimental data in the experimental conditions for each contact material.

The authors have been interested in a Scanning Laser Microscope (SLM) and applied it to studies of contact phenomena. In particular, a digital SLM is being currently used, and confirmed to be a successful tool for investigating the contact phenomena. In this paper, the theory and mechanism of a digital SLM are briefly explained, and some actual data obtained with the digital SLM are presented for demonstrating its usefulness for studies of contact phenomena.

AgCdO12wt% contacts mounted on electromagnetic relays are tested in a DC 42 V-8.4 A resistive circuit as make-only contacts and break-only contacts. In this experiment, the arc duration has been measured for each operation and the shape of the transferred pip on each contact has been observed using photograph records taken every 1000 operations. The transferred pip grows markedly at make-only contacts. Furthermore, as a few samples with the long arc duration have the flat hill transferred from the cathode on the anode surface of break-only contacts, we believe that the transferred direction reverses at a certain arc length.

Large number of electronic connectors are widely used in various electronic and telecommunication systems. No matter whether it is optical telecommunications or mobile phone systems, connectors are important links for electronics. Unfortunately connector contacts are exposed in air, they are different from any other electronic components, the contacts are greatly influenced by the environment where they operate. In China, dust and corrosion products are the main contaminants to cause contact failure. Evidently the failed contacts seriously deteriorate the reliability of electronic and telecommunication systems. This paper summarizes the recent achievements obtained by our Lab on the effect of dust and corrosion products to the connector contact failure. Since dust contamination is a very complex problem which is not only popular in China, but also happened in many countries. Continuous studies will be very useful to improve the contact reliability of connectors, setting up new and effective testing methods and standards, building up experimental and computer simulation systems.

Telecom- and Signal Relays with gastight plastic sealed housings enables the usage of inert and highly insulating gases. Although plastic sealed housings are used, optimized designs can keep the gas during the entire life of more than 25 years. The application of this technology allows the application of highly insulting gases like SF₆ and result in a significant reduction of the relay size as reduced physical dimensions can be applied. With unchanged distances a significantly better dielectric performance can be achieved, without a relevant cost increase. Furthermore the inert switching atmosphere increases the switching characteristics or reduces the consumption of precious metals for the contacts. Even the usage of less precious metals like tungsten or ruthenium might be possible for switching typical telecommunication signals.

Nowadays electronic devices and systems are widely used in various dynamic environments. However, they cause electrical contact instability that can easily be ignored. This phenomenon is considered as contact failure caused by a dynamic influence. In this paper, the investigation of contact failure caused by dynamic influences and analysis method for such contact failure are discussed. The results show that a dynamic influence could not be well covered in the experimental testing for a new product.

Various optical fiber connectors have been developed during the 20 years since optical fiber communications systems were first put into practical use. As the domain of optical fiber communication systems expanded from trunk lines to subscriber lines and customer premises the main focus changed from performance improvement to miniaturization and cost reduction. This paper describes the technical background, recent trends in standard optical connectors, and recent issues related to photonic connection technologies.

We developed a new MU-type fixed optical attenuator for 4.5 mm pitch packaging. We succeeded in miniaturizing the attenuator by adopting a design employing an MUJ plug. This fixed optical attenuator achieved a tensile strength of greater than 70 N, which is the same as that of a conventional fixed optical attenuator, and also exhibited good environmental and mechanical durability. The new fixed optical attenuator can be used in existing communication devices in which 4.5 mm pitch MU adaptors are already installed.

Some electromechanical devices and systems produced using MEMS fabrication processes are detailed. Two precision measurement metrologies for inspecting electromechanical products are also described. As the trend of electromechanical devices has been towards smaller and smaller sizes possessing robust mechanisms and powerful functions, micro-electric-mechanical system (MEMS) devices are becoming more the choice for meeting such requirements. Three MEMS examples are discussed in detail in this paper: CMOS compatible sensors, RF/microwave components, and packaged and integrated passive devices. The design thinking of a new free-fall sensor, which is an accelerometer and possesses a surprisingly low frequency response and broad bandwidth, is mentioned. In addition, an AVID (dvanced ibrometer/nterferometer evice) system for measuring tiny displacement as well as a Morphinscope system that has the advantage of a confocal microscope combined with a photon tunneling microscope and both developed by NTU's MEMS/NEMS group, are discussed. The excellent sensing ability of the free-fall sensor and the accuracy resolution of the two measurement systems are proved by experimental verification.

As a new material, silver (Ag) coated fabric has been developed, and its use for shielding electromagnetic radiation is expected. In this paper, seven kinds of Ag coated fabrics, woven, knitted and nonwoven by Ag coated fibers, are prepared, and placed over a PCB with a microstrip line, which is used as a noise source. By measuring the input impedance of the microstrip line, the distance between the PCB and the fabric is fixed to 8 mm to reduce the coupling paths. The shielding effect SE of those fabrics was compared by measuring the magnetic near-field with a small shielded-loop probe. In the results, the resonance frequency is dependent on the fabric's length, as well as the case of a copper sheet. Comparing the texture, the SE of woven and nonwoven fabrics is larger than the knitted fabric. Comparing with the copper sheet, the SE of the fabrics is smaller below 200 MHz, but elsewhere is almost the same.

To estimate the electromagnetic noise radiated from a printed circuit board (PCB) driven by a switching device, the finite difference time domain (FDTD) simulation method implementing the switching transistor is developed. The electric and magnetic field distributions on the signal line driven by a switching transistor are calculated or measured. These calculated and measured results show good agreement. The electric and magnetic field noises at typical impedance conditions modeled for the switching condition, i.e., the ON or OFF state of the transistor, are estimated by the FDTD calculation. The variation of the radiation noise when the switching transistor is turned ON or OFF is large at 216 MHz, whose input impedance of the signal line is small. It is speculated that the noise radiation at the 10 Ω signal source impedance condition that is modeled for the ON condition shows good agreement with the noise distributions at the driving condition.

Gallium nitride (GaN) is one of the wurtzite-type materials and has semiconducting properties. Crystallinities of GaN thin films are usually poor when they are directly grown on polycrystalline metal-foils which are expected as substrates for realizing novel giant microelectronic devices. Improvements of crystal orientations of GaN thin films grown on such polycrystalline metal-foils are tried by using several kinds of intermediate layers. Aluminum nitride (AlN), GaN, silicon dioxide (SiO₂) and Si are chosen as materials for the intermediate layers. The crystal orientations of GaN thin films grown by inserting the SiO₂ and Si intermediate layers with adequate thicknesses are markedly improved, while those grown on the AlN or GaN intermediate layers are not improved. These differences are not caused by the kinds of the materials used for the intermediate layers but by differences in their crystallinities.

The key elements of sub-100 nm MOSFET modeling for circuit simulation are accurate representation of new physical phenomena arising from advancing technologies and numerical efficacy. We summarize the history of MOSFET modeling, and address difficulties faced by conventional methods. The advantage of the surface-potential-based approach will be emphasized. Perspectives for next generations will be also discussed.

A review of the basic passive components available in mixed-signal silicon IC technologies for applications up to millimetre-wave frequencies is presented. These include: inductors, capacitors, resistors, and quasi-distributed devices such as transmission lines and transformers. Applications for these devices range from resonant tanks to impedance matching, phase shifting and feedback networks. Device physics and electrical models of these passives are reviewed along with their physical layout, verification data from computer simulation, and experimental characterization. The emphasis is on lumped-element equivalents for linear and non-linear circuit design of wireless and wireline circuits in silicon VLSI technologies.

A three-mode switched-LNA has been developed using a 0.25 µm SiGe BiCMOS technology. The LNA features low noise figure (NF) performance, while achieving both low dissipation power and low distortion characteristics. The proposed MOSFET switch incorporating a newly developed switch circuit with a triple-well structure, which changes the LNA's mode, provides a parasitic capacitance of just 0.52 times that of a conventional MOSFET switch. This results in a significant NF improvement, by 0.16-0.33 dB, for the three-mode switched-LNA compared to a conventional LNA. Extensive studies of the MOSFET switch with regard to the structural parameters and the doping profiles are reported. Experimental results and the overall performance of a trial IC incorporating the three-mode switched-LNA are also given.

The performance of radio frequency integrated circuits (RFICs) in silicon-on-insulator (SOI) technology can be improved by using a high-resistivity SOI substrate. We investigated the correlation between substrate resistivity and the performance of a low noise amplifier (LNA) on ELTRAN(R) SOI-Epi wafers^TM, whose resistivity can be controlled precisely. The use of high-resistivity ELTRAN wafers improves the Q-factor of spiral inductors, and thereby increases the gain and narrows the bandwidth of the LNA. Using the high-resistivity ELTRAN wafers, we have successfully fabricated a 2.4-GHz and 5-GHz CMOS LNA in 0.35-µm SOI CMOS technology, whose process cost is lower than the latest CMOS technologies.

A fully integrated 2 V 2.4 GHz CMOS low-noise amplifier (LNA) is presented in this paper. A negative resistance circuit is used to reduce the parasitic resistors of the on-chip spiral inductor and increase the quality factor (Q). An inductor is added to the common-source and common-gate transistors of the cascode circuit to improve matching and increase power gain. The LNA is designed according to the tsmc 1P4M 0.35 µm process. The parasitic effect of the on-chip spiral inductor was considered. With a 2 V supply, the power gain of the LNA is 19.5 dB, the noise figure is 2.7 dB, and the power dissipation is 15.2 mW. The input third-order intercept point (IIP3) is 0 dBm. The input -1 dB compression point (P_-1dB) is -13.9 dBm. The reverse isolation S12 is -44.1 dB.

The paper presents a dual-band switchable low noise amplifier implemented in 0.25-µm CMOS technology for 5-GHz wireless multimedia applications. The high-speed wireless multimedia applications call for broadband design techniques for RF circuits. Instead of using conventional broadband techniques not well suitable for CMOS implementation, a dual-band switchable load is proposed for broadband LNA design. The dual-band switchable load enables the LNA operate at the lower or the upper band at 5-GHz band by a 1-bit control signal. The LNA exhibits over 17 dB power gain, 3.5 dB noise figure and input 1-dB compression point -23 dBm in both frequency bands. It draws 9.5 mA from 2.5 V supply. The power gain remains larger than 16 dB as temperature varies from -5 to 65.

The low phase noise, low supply voltage 1.3 GHz CMOS VCO has been realized by 0.25 µm standard CMOS technology without any trimming and any tuning. The phase noise characteristics of -109 dBc/Hz and -123 dBc/Hz at 100 kHz offset and 500 kHz offset were achieved from carrier, respectively, with 1.3 GHz oscillation frequency at 1.4 V supply voltage. The performance of 1.4 V supply voltage phase noise was superior to that of 2.0 V supply voltage phase noise due to low output impedance current source. The tuning ranges of 13.3%, 16.6%, and 20.1% for 1.4 V, 1.8 V, and 2.0 V supply voltage were achieved, respectively. The amplifier consisted of one pair of PMOS differential stage with large gate length NMOS current source to realize low supply voltage operation and to avoid flicker noise contribution for phase noise. The on-chip spiral inductor consisted of three terminals arranged in a special shape to obtain high Q and small chip area. The power dissipation of this VCO was 22.4 mW without buffer amplifier.

A linear-in-dB VGA of the current-divider type is fabricated in 0.25 µm CMOS technology. Two gain compensation techniques are proposed in order to compensate the gain deviations due to a MOSFET which has a square-law characteristic or an exponential-law characteristic determined by its current density. Temperature compensation techniques are also proposed. Measure results obtained at 380 MHz are a gain range of 80 dB, a gain error of 3 dB, and an NF of 11 dB.

This paper describes the design of a 2.7 V operational, 200 MS/s, 14-bit CMOS D/A converter (DAC). The DAC consists of 63 current cells in matrix form for an upper 6-bit sub-DAC, and 8 current cells and R-2R ladder resistors for a lower 8-bit sub-DAC. A source degeneration resistor, for which a transistor in the triode operational region is used, is connected to the source of a MOS current source transistor in a current cell in order to reduce the influence of threshold voltage (Vth) variation and to satisfy the differential nonlinearity error specification as a 14-bit DAC. In conventional high-speed and high-resolution DACs that have the same design specifications described here, spurious-free dynamic range (SFDR) characteristics commonly deteriorate drastically as the frequency of the reconstructed waveform increases. The causes of this deterioration were carefully examined in the present study, finding that the deterioration is caused in part by the input-data-dependent time-constant change at the output terminal. Unexpected current flow in parasitic capacitors associated with current sources causes the change in the output current depending on the input data, resulting in time-constant change. In order to solve this problem, we propose a new output circuit to fix the voltage at the node where the outputs of the current sources are combined. SPICE circuit simulation demonstrates that 63 dB of SFDR characteristics for the 90 MHz reconstructed waveform at the output can be realizable when the supply voltage is 2.7 V, the clock rate is 200 MS/s, and the power dissipation is estimated to be 300 mW.

A voltage-controlled ring oscillator with an RC delay as an additional delay to vary the oscillation frequency is proposed. The use of MOS resistors provides a wide range tuning ability from 40 Hz to 366 MHz. The proposed circuit also enables implementation of a low frequency voltage-controlled ring oscillator with relatively smaller devices than the conventional one.

Fully embedded spiral inductors in a low loss dielectric multi-layer were designed and fabricated using a low temperature co-fired ceramics (LTCC) technology for RF SIP (system in package) integrations. The line width/space and the number of spiral layers were optimized within five layers of LTCC dielectric for high Q-factor, high self-resonant frequency (SRF), process easiness, and compact size. The embedded multi-layer spiral inductors reveal better performance in terms of Q-factor, SRF and the effective inductance L_eff than planar spiral inductors of the same dimension and number of turns. The optimized multi-layer spiral inductor shows maximum Q of 56, L_eff of 6.6 nH at Q_max and SRF of 3.6 GHz while planar spiral inductors have maximum Q of 49, L_eff of 5.8 nH at Q_max and SRF of 3.0 GHz.

A simple modeling technique for symmetric inductors is proposed. Using the proposed technique, all model parameters for an equivalent circuit of symmetric inductors are easily calculated from geometric, process and substrate resistance parameters without using electromagnetic (EM) simulators. Comparison of simulated results with measured results verifies the effectiveness of the proposed modeling technique up to 5 GHz with center-tapped or non-center-tapped configurations.

This paper deals with the wave scattering from a periodic surface with finite extent. Modifying a spectral formalism, we find that the spectral amplitude of the scattered wave can be determined by the surface field on only the corrugated part of the surface. The surface field on such a corrugated part is then expanded into Fourier series with unknown Fourier coefficients. A matrix equation for the Fourier coefficients is obtained and is solved numerically for a sinusoidally corrugated surface. Then, the angular distribution of the scattering, the relative power of each diffraction beam and the optical theorem are calculated and illustrated in figures. Also, the relative powers of diffraction are calculated against the angle of incidence for a periodic surface with infinite extent. By comparing a finite periodic case with an infinite periodic case, it is pointed out that relative powers of diffraction beam are much similar in these of diffraction for the infinite periodic case.

The energy conservation law and the optical theorem in the grating theory are discussed: the energy conservation law states that the incident energy is equal to the sum of diffracted energies and the optical theorem means that the diffraction takes place at the loss of the specularly reflection amplitude. A mathematical relation between the optical theorem and the energy conservation law is given. Some numerical examples are given for a TM plane wave diffraction by a sinusoidal surface.

We propose a new detection method of a 2-dimensional pH image to measure the pH distribution of test materials by illuminating a frequency modulated light to LAPS using a chopping wheel. It could simultaneously measure signals in one line by applying a modulated light with a different frequency for each pixel, using a chopping wheel for modulating the frequency, and calculating an amplitude with respect to a frequency component by the light source. To test the proposed method, we implement a chopping wheel in consideration of a LAPS's characteristic, and reconstructed an image by frequency analysis using the implemented chopping wheel and 4 mm test pattern image. As a result, we verified that the proposed method using the chopping wheel was able to detect 30 times faster a 3030 pixels pH image having a PSNR more than 22 dB above the conventional method.

Utilizing a macromodel which calculates the floating gate potential by combining resistances and dependent voltage and current sources, DC transfer characteristics for multi-input neuron MOS inverters and for those in the neuron MOS full adder circuit are simulated both at room temperature and at 77 K. Based on the simulated results, low temperature circuit failures are discussed. Furthermore, circuit design parameter optimization both for low and room temperature operations is described.