A Transmission Line Sensor With Sensitivity Improved for Detection of Ionic Concentration in Microfluidic Channel

This paper describes a design method for flip-chip monolithic millimeter-wave integrated circuits (MMICs) with a coplanar waveguide (CPW) transmission line for W-band applications. We proposed a test structure for obtaining accurate flip-chip CPW line models. We examined the transmission line characteristics of the CPW line using the test structure in the millimeter-wave range and modeled them. Using the CPW line models, we designed and fabricated both two- and three-stage amplifiers using 0.15-/spl mu/m InGaP/InGaAs high electron-mobility transistor technology. The maximum power gain of the two-stage amplifier is 12 dB at 79 GHz. The three-stage amplifier has a maximum power gain of 16 dB at 77 GHz. The agreement of measured S-parameters with calculated results demonstrates that the proposed test structure is suitable for characterizing flip-chip CPW lines and provides very accurate models.

This paper proposes a modified Co-Planar Waveguide (CPW) transmission line with Periodic Defected Ground Structures which can be used as a high-speed microwave channel for embedded antennas. CPW ground surface is modified by making slots of various shapes. The modified CPW channels are found suitable for Wi-MAX applications and a particular shape of DGS unit cell can be selected depending on the bandwidth requirement. The CPW transmission line with circular shaped DGS cells of two columns offer a remarkable value of the transmission coefficient of 0.89022 (− 1.01 dB) therefore it is fabricated and tested. It is observed that both the simulated and tested results agree with each other.

A non-integrated type noise filter on a Coplanar Waveguide (CPW) transmission line is demonstrated by using a highly resistive Co₄₁Fe₃?Al₁₃O? nanogranular thin film with the dimensions of 4 ㎜(l) × 4 ㎜(w) × 0.1㎛ (t). The noise suppression characteristics are evaluated without placing an insulating layer between the CPW line and the magnetic thin film. The insertion loss is very low being less than 0.3 ㏈ and this low value is maintained up to 2 ㎓. At a ferromagnetic resonance frequency of 3.3 ㎓, the power loss is very large and the degree of noise attenuation is measured to be 3 ㏈. This level of noise attenuation is still small for real applications; however, considering the small magnetic volume used in this work, further improvement is expected by simply increasing the magnetic volume and by integrating the magnetic thin film into the CPW transmission line.

We have developed a micro fluxgate magnetic sensor using new printed circuit board (PCB) technology. The fluxgate sensor consisted of five PCB stack layers including one layer of magnetic core and four layers of excitation and pick-up coils. The center layer as a magnetic core was made of micro patterned amorphous magnetic ribbon with an extremely high DC permeability of ~100,000, and the core had a rectangular ring shape. Four outer layers as an excitation and pickup coils had a planar solenoid structure. The amorphous magnetic core was easily saturated due to the high permeability, low coercive field, and closed magnetic path for the excitation field. The chip size of the fabricated sensing element was 7.3 × 5.7 mm2. Excellent linear response over the range of –100 μT to +100 μT was obtained with sensitivity of 780 V/T at excitation sine wave of 3 Vp-p and 360 kHz. A very low power consumption of ~8 mW was measured. This low power, small size, and high sensitive fluxgate sensor to measure a low magnetic field is very useful for various applications.

The use of Printed Circuit Board (PCB) technology for device packaging offers new opportunities to solve these challenges. During the past decade embedding of semiconductor chips into PCB structures evolved from a research topic to volume production. The paper will briefly describe this development and categorize today's embedding technologies. First modules with embedded chips are in production in Asia and Europe, mainly for mobile applications. In Europe embedding has gained a strong interest for power modules, especially in automotive applications. Main drivers are the capability for compact and thin packaging, the high reliability and cost saving potential. The automotive industry has a strong demand for highly reliable and cost-efficient electronics. Especially the upcoming generations of hybrid cars and fully electrical vehicles need compact and efficient 400 V power modules. Within the engine compartment installation space is of major concern. Therefore small size and high integration level of the modules are needed. Embedding of power switches, and controller into compact modules using PCB (Printed Circuit Board) technologies offers the potential to reduce the thickness and size of the module. In order to replace DCB ceramics, a structure of thermal laminate material between Cu layers has been developed and the capability for thermal conduction and electrical insulation has been evaluated. For the assembly of large power IGBTs with sizes of 100 mm² and larger, new silver sintering pastes have been evaluated. They enable a pressure-less sintering at 200 °C, compatible with PCB materials. To handle the high switching current of up to 200 A, suitable copper tracks in the PCB are required. The realization of such thick copper lines with thickness up to 1 mm requires advanced processing, compared to conventional multilayer PCB production. In order to form complex power systems out of modules with embedded chips interconnections by Ag sintering are under development.

This paper introduces the design of an air-filled substrate integrated waveguide (AFSIW), and a transition design from microstrip line (ML) to AFSIW at 60 GHz. The proposed structure is realized by printed circuit board (PCB) technology so that the fabrication cost is low and the whole structure is easy to be integrated with other planar components. An equivalent circuit model of the proposed ML-AFSIW transition is proposed and verified by full-wave simulation. To verify the proposed idea, a back-to-back transition is designed, fabricated and measured. The measured return loss is higher than 15 dB from 60.6 to 64.5 GHz. The minimum of measured insertion loss is 0.2 dB at 61 GHz. The measured results show that the proposed ML-AFSIW transition is suitable for millimeter-wave (mm-Wave) application.

A planar transmission-line configuration for rapid, nondestructive, wideband permittivity measurements of liquid and semisolid materials at microwave frequencies is described. The transmission-line propagation constant of the proposed configuration is determined with the multiline technique from scattering parameter measurements of two lines with a known length difference. Guidelines for the appropriate selection of the line dimensions and a technique for resolving the phase ambiguity associated with the multiline technique are presented. The material permittivity is related to the propagation constant by closed-form expressions that allow the permittivity to be determined by a relatively simple numerical inversion procedure. The proposed sensor has the advantage of not requiring the sample to have uniform edges, nor that they are perpendicular to the planar line. The technique used for determining the line propagation constant has the advantage of not requiring any transmission-line discontinuities to be explicitly modeled. To illustrate the technique, a coplanar waveguide transmission-line sensor was fabricated and used to measure the permittivity of six liquids and four gelatin samples from 1 to 5 GHz. These measurements agree very well with coaxial-line probe measurements, demonstrating the accuracy of the proposed configuration. The sensitivity of the results to dimensional tolerances is demonstrated.

Printed circuit boards (PCBs) are designed for packing two or more semiconductor chips. On these PCBs, there are various types of faults in the wiring. We must therefore test the PCBs to detect these faults, and it is essential to establish an efficient testing method. One type of test method uses two probes. Two probes, each touching one edge (end) of an inter-chip wiring, are used to check for the presence of faults. Testing is complete when we have confirmed that no faults exist on the PCB. The objective is to minimize the completion time for the testing, that is, our aim is to design efficient routes for the two probes; this is a two-probe routing problem. Several previous studies have proposed an approach involving a two-phase method. Although the two-phase method quickly finds a feasible solution, there is no guarantee that the solution is good. Besides, in recent years, PCB technology provides dense assembly capability and increased chip packaging; this implies that the scale of the two-probe routing problem becomes larger and the problem is difficult to be solved. We therefore propose a new approach, where we formulate a two-probe routing problem as a combinatorial optimization problem and then, we solve the combinatorial optimization problem by using genetic algorithm.We expect that our approach is useful for solving the large-scale problems. In computational experiments, we compare the results of our approach with those obtained using the two-phase method, and we show that our approach outperforms the two-phase method.

A compact planar dual band-notched ultrawideband (UWB) MIMO antenna array is presented. The proposed antenna array consists of two same elements which act as 3.4/5.5GHz dual band-notched UWB antennas on a printed circuit board. The antenna array is fed by using two 50Ω coplanar waveguide (CPW) transmission lines with two feeding ports. By placing a central metal strip between two radiating elements, the mutual coupling can be reduced. The proposed antenna array is successfully simulated, designed, and measured showing broadband matched impedance, stable radiation patterns and constant gain in terms of isolation of |S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> |<;-30dB. The calculated envelope correlation coefficient between two elements shows consistent diversity performance across the UWB bandwidth.

Since the 1960s, interconnection technology has been dominated by implementations of printed circuit board (PCB) technology. However, in response to the ever increasing demand for higher routing densities and improved electrical performance, this technology has been increasingly challenged by multichip module (MCM) technology and in particular the MCM‐L type. MCM‐L technology is a laminate construction and is basically a further development of PCB technology with two or more bare chips and fine line interconnects. Consequently, it is perceived that the current PCB fabricators are ideally positioned to take the initiative with MCM‐L technology. Reviews the current state of PCB industry and MCM‐L technological (process and material) requirements, within the UK, such that a comparison can be made between the two technologies. Planning, training and investment requirements for new technology implementation are then identified and compared with PCB fabricators’ technological, training, planning and investment capabilities. The shortfalls between MCM‐L fabrication requirements and PCB fabricators capability are identified and discussed.

One of the beneficial methods being widely used to preserve genetic resources of imperiled animals or improved agricultural animals is cryopreservation of germplasm. During this process, the biological structure of the cells remains relatively intact by freezing and storing them at very low temperatures. Freezing condition plays an essential role in cryopreservation procedure since the exposure of the cells to low temperature can cause damage to the cells [1]. Therefore, accurate monitoring of the freezing process can improve the recovery rate of the cells after thawing. During the phase change phenomena, the dielectric and conduction properties of ice changes [2]. Herein we present, a portable platform for monitoring of the freezing and thawing processes based on the electrical impedance of the samples during cryopreservation. The system is composed of a portable temperature and impedance measurement system in conjunction with an impedance sensing probe fabricated with printed circuit board (PCB) technology. The impedance measurement circuit, temperature measurement circuit, control unit for data acquisition and wireless communication and touch screen LCD with a graphical user interface are the building blocks of the measurement system that enables users to perform impedance measurement at single or multiple frequencies with various excitation signals (Figure 1A). Utilizing impedance measurement instead of DC resistance measurement enable us to monitor both dielectric properties and resistance changes during phase change and avoids the polarization of the electrodes. In addition, an impedance sensing probe was developed by using PCB technology, which provides accurate electrodes fabrication at low cost. The probe has been designed to be used within 0.5 ml French straw which is a conventional container in cryopreservation application. Pair of parallel electrodes were fabricated on the probe at three detection zones (Figure 1B). The system was evaluated at different cryopreservation conditions including various sample solutions and cooling rates. Hank's Balanced Salt Solution (HBSS) is being widely used in cryopreservation to maintain cells in a viable state. The system was characterized by measuring the impedance in HBSS and DI water solutions solution. The 0.5 ml French straws were filled sample solution along with the probe and a T-type thermocouple. Next, the samples were placed on top of the liquid nitrogen with a 2 cm gap to freeze, and after the sample temperature reached lower than -40 oC, the samples were left at room temperature to thaw. During this process, the impedance and temperature were measured inside the samples. Figures 1C and 1D show the magnitude and phase of the measured impedance for HBSS and DI water sample respectively. When the HBSS sample starts to freeze, the impedance magnitude does not change before the latent heat removal stage. However, the impedance phase starts to increase after the sample cools down. It reaches a minimum value during nucleation and increases during latent heat removal. Therefore, the phase change phenomena can be detected with the imaginary part of the impedance. In the DI water case, the impedance starts to increase by cooling down the solution when the nucleation happens there it remains relatively constant, and it keeps increasing after that. This shows that the solution containing various ions has different impedance characteristics, which can be used as a parameter to monitor the cryopreservation phenomena. The system was also characterized by different solutions containing salts and cryoprotectants, frozen at various cooling rates, to further investigate the potential of impedimetric sensors in quality control for cell freezing protocols. Figure 1

The design and development of novel microelectromechanical systems’ (MEMS) coplanar waveguide (CPW) transmission lines, using microshield and groove, are presented in the paper to operate between 5–60 GHz. The quasi-static capacitances of CPW are calculated using the conformal mapping technique to express the propagation properties, i.e., the characteristic impedance and effective permittivity. Simulation results have shown a considerable loss reduction to levels that compare favorably with the conventional CPW. These transmission lines can be widely used in the development of phase shifters, filters, and antennas, because of their advantages in loss reduction and improvement in the performance.

The rapid development of information and communication technologies has driven the rapid growth of data traffic and the large requirement of high-speed optical transceiver modules. Usually, optical subassemblies through flexible printed circuit boards (PCBs) connect with the hard PCBs to compose as optical transceiver modules. Because of the impedance mismatch of connection between flexible PCB and hard PCB, the operation bandwidth of the module can be limited. In this paper, the design of connection between flexible PCB and hard PCB in optical subassembly modules will be investigated for increasing the operation speed of the module. First, the transmission bandwidth of flexible PCB is analyzed. High-frequency performances of three transmission line structures, micro-strip line, grounded coplanar waveguide, and top ground micro-strip line, are investigated in flexible PCB. High-frequency performances of flexible PCB with different bending types are also investigated. The flexible PCB has been verified to be suitable to use in 25 Gb/s applications. Next, the high-speed transmission performance is analyzed through the connection between flexible PCB and hard PCB, because the impedance mismatch usually occurs at the connection. The ground pads are added near the signal line of flexible PCB, and the ground pads are connected to the ground layer in PCB through ground vias. The anti-pad in hard PCB is added under the signal solder pad. The dip of S21 response can be eliminated by the optimized ground pad. The impedance mismatch can be reduced by the optimized anti-pad, the impedance increases from 40-Ω to 49-Ω at the connection between flexible PCB and hard PCB, and the transmission bandwidth can increase from 16.5 GHz to 23.5 GHz. TO-46 header is a common and low-cost packaging solution for DFB laser and photodiodes. The connection between flexible PCB and TO-46 header is also investigated. While the connection has a gap, the dip of frequency response will occur at lower frequency. While the connection is very close, the bandwidth can be larger than 25 GHz. The flexible PCB, hard PCB, and TO-46 header are combined together, and the 23 GHz transmission bandwidth can be obtained. The 25 Gb/s transmission eye diagram is also measured, and the eye height, rise time, fall time, and Q-factor are 268.14 mV, 13.78 ps, 13.56 ps, and 8.76, respectively. The combined flexible PCB, hard PCB, and TO-46 header are verified to be suitable to apply in 25 Gb/s optical subassembly modules, and will be able to be used in 100G Ethernet.

High density interconnect printed circuit board technology enables significant board size and layer count reduction. Thinner inner layer dielectric materials, reduced line widths, and closer spaced components inherent in high density board technology require a change in electrical design methodology. Most notably, the thinner dielectric thickness significantly impacts the electrical performance of the circuit board with respect to crosstalk, board capacitance, via inductance, and controlled impedance. Via inductance is significantly reduced as mechanically drilled through hole vias are replaced with microvias. Distributed capacitance will tend to increase because of the thinner dielectric layer and crosstalk between signal traces run on adjacent layers may also increase. Using either FR-4 type epoxy (diel, cnst.=4.0) or higher performance materials (diel, cnst.=2.8) conventional controlled impedance structures such as a stripline, microstrip, and coplanar waveguide are possible to design using current manufacturing capabilities. A 50 /spl Omega/ impedance can be achieved by a microstrip or a coplanar waveguide using either dielectric material. The stripline can only achieve approximately 35 /spl Omega/ with the higher performance material and 25 /spl Omega/ with the FR-4 type epoxy material. A 500 mW radio frequency receiver and transmitter module operating at 467 MHz was successfully fabricated using a three layer build-up high density circuit board. The circuit board construction had one build-up layer fabricated with a liquid epoxy material. The circuit board electrical design incorporated microstrip, stripline, and coplanar waveguide controlled impedance structures. The results of the electrical performance measurements indicated that transmitted power, receiver sensitivity, and frequency specification performance were similar to a six layer board manufactured with conventional technology.

We demonstrate a new method for determining the frequency-dependent dielectric properties of thin-film materials at microwave frequencies using coplanar waveguide (CPW) transmission line measurements. The technique makes use of the complex propagation constant determined from multiline thru-reflect-line (TRL) calibrations for CPW transmission lines to determine the distributed capacitance and conductance per unit length. By analyzing data from CPW transmission lines of different geometries, we are able to determine the complex permittivity of the dielectric thin film under study as a function of frequency from 1 to 40 GHz. By performing these measurements under an applied bias voltage, we are able in addition to determine the tuning and figure of merit that are of interest for voltage-tunable dielectric materials over the frequency range 1 to 26.5 GHz. We demonstrate this technique with measurements of the permittivity, loss tangent, tuning, and figure of merit for a 0.4 µm film of Ba0.5Sr0.5TiO3at room temperature.