The performance of GaN power devices has been rapidly improving. Recently, the main approach is the use of AlGaN/GaN HEMT structures on Si substrates, for which the target breakdown voltage is initially 600V or less. Although issues still remain with regard to current collapse and the threshold voltage required for normally-off operation, many companies have announced their intention to commercialize such devices. In this report, recent developments concerning GaN power devices are reviewed, and unresolved issues and future expectations are discussed.

View full abstract

Four most basic topics to understand the “Magnetic resonance” wireless power transfer system are discussed, the naming, power transfer efficiency, transferred power and how to connect resonator and external circuit. Emphasis is on the use of 0 ohm power source instead of 50 ohm signal source that is popular among the communication engineers. The misleading name “magnetic resonance” is criticized to give more correct picture of the resonance.

View full abstract

Microwave power transmission (MPT) has had a long history before the more recent movement toward wireless power transmission (WPT). MPT can be applied not only to beam-type point-to-point WPT but also to an energy harvesting system fed from distributed or broadcasting radio waves. The key technology is the use of a rectenna, or rectifying antenna, to convert a microwave signal to a DC signal with high efficiency. In this paper, various rectennas suitable for MPT are discussed, including various rectifying circuits, frequency rectennas, and power rectennas.

View full abstract

Wireless power transmission is the new technology that transmits power without electrical connection. There are different approaches to wireless power transmission such as electromagnetic induction, electromagnetic resonance, and microwave power transmission. In this paper, we introduce a mobile phone power charger based on electromagnetic induction, and we built a wireless power charger (the primary side), and a mobile phone battery cover (the secondary side) equipped with built-in planar coils. In experiments, we evaluate the impact of the position and distance between the coils on the primary and secondary sides on performance and the power conversion efficiency of the wireless charger.

View full abstract

This paper presents a new high speed 5-2 compressor. It is designed based on a new truth table which leads to a simple structure. Also, the driving problems are reduced. Due to the similar paths from inputs to the outputs, there will be no need for extra buffers in low latency paths to equalize the delays and the power dissipation is decreased. Furthermore, by use of full swing logics, the speed of cascaded operations is enhanced. The latency of proposed design is 440ps.

View full abstract

Coherence is an important quality of radar signal. DDS + PLL Hybrid scheme becomes one of the most important and dynamic research in signal generating. In this paper, a novel DDS + PLL Hybrid scheme with the sweeping voltage circuitry is proposed to solve the problems in the classical scheme, such as poor stability, large design difficulty and long acquisition time. Meanwhile, pre-distortion is also proposed to compensate the static phase error, which improves the coherence and pulse compression performance. The measurements of the test system indicate the proposed scheme reduces the acquisition time and improves the coherence effectively.

View full abstract

In this paper, we propose a new memory efficient IFFT design method for OFDM-based applications, based on a signed integer mapping of three IFFT input signals which are composed of modulated data, pilot and null signals. The proposed method focuses on reducing the word size of memory in the first two stages of the single-path delay feedback (SDF) IFFT architectures since the first two stages require 75% of the overall memory. By Synopsys simulation of the first two stages of IFFT, it is shown that the proposed method achieves about 40% reduction in area and 44% reduction in power consumption compared with the previous work.

View full abstract

A highly linear, low voltage, low power, low noise amplifier (LNA) using a novel nonlinearity cancellation technique is presented in this paper. Parallel Inductor (PI) matching is used to increase LNA gain by 3dB at the desired frequency. The linear LNA was designed and simulated in a TSMC 0.18μm CMOS process at 5GHz frequency. By employing the proposed technique, the IIP₃ is improved by 12dB in contrast to the conventional folded cascode LNA, reaching −1dBm without having any significant effect on the other LNA parameters such as gain, NF and also power consumption. The proposed LNA also delivers a voltage gain (S₂₁) of 12.25dB with a noise figure of 3.5dB, while consuming only 1.28mW of DC power with a low supply voltage of 0.6V.

View full abstract

We propose a new method for the antenna phase center determination based on measurement. The phase center position and the delay of wave propagation through a Vivaldi antenna are estimated from the measured arrival-time of a multi-offset transmission signal. The estimated phase center position agrees well with that determined by a numerical simulation. The estimated delay has also been validated to have a good accuracy by a laboratory experiment. Then we demonstrate that the accuracy of the range distance estimation by a radar system using a Vivaldi antenna can greatly be improved by considering the phase center position.

View full abstract

{2ⁿ, 2ⁿ-1, 2ⁿ+1} is one of the most commonly used moduli in residue number systems. In this express, we propose a novel comparator for the moduli {2ⁿ, 2ⁿ-1, 2ⁿ+1}. Based on the proposed architecture, we can design high speed comparator for the moduli {2ⁿ, 2ⁿ-1, 2ⁿ+1}, which is the fastest among all known comparators for the moduli {2ⁿ, 2ⁿ-1, 2ⁿ+1}. The performance of the proposed comparator is evaluated and compared with the earlier fast comparators for the moduli {2ⁿ, 2ⁿ-1, 2ⁿ+1}, based on a simple gate-count and gate-delay model. The proposed comparator can improve the state-of-art by 8% on the average in terms of area and 6% on the average in terms of performance delay.

View full abstract

In this paper, an input inductive network for the wideband LNA is proposed. The two input inductors located in and out of the feedback loop are set respectively to combine with the conventional resistive feedback structure. Input matching and NF of the LNA can be optimized separately by varying the value of the two input inductors without significant influence from one to the other. The proposed cascode LNA was analyzed, designed, and fabricated in the IBM 0.13μm CMOS technology to verify the concept. A −10dB S11 is achieved in a wide range of frequency from 1GHz to 3GHz. Within this bandwidth, the LNA has a gain of 7.5dB and a minimum noise figure of 2.5dB while consumes a 7mW of power. The results indicate that the proposed input-network effectively alleviates the tradeoff between noise figure and bandwidth without requiring extra power consumption.

View full abstract

A compact path-loss measurement system for design of in-vehicle short range communication is proposed. The system is composed of sensor network modules for data transmission and a transceiver for the sounding signal. The channel is measured in an engine compartment of a hybrid vehicle using the developed system. As a result, it is clarified that the engine compartment has a severe fading channel.

View full abstract

In optical Network-on-Chip (NoC), packet switching remains popular owing to its scalability and reliability. Considering no mature optical buffering technology, deflection routing is preferable to resolve the output port contention. Reduction of deflection probability is essential to bufferless deflection optical NoC. This letter proposes a new 5*5 router architecture, and especially a deflection-supported switching fabric. Moreover, an ejection unit and an injection unit are designed to reduce the deflection. Additionally, priority-based routing computation and port allocation algorithms are designed based on the new switching fabric. The simulation results show that our proposal can improve performance at acceptable insertion loss.

View full abstract

The memory polynomial (MP) model is a frequently used structure for digital predistortion (DPD) of power amplifiers (PAs) in wireless communication systems, but it has limited performance. In this paper, we propose a compound memory polynomial (CMP) model to enhance the accuracy. The CMP model is constructed by adding the terms concerning the difference of the input to the MP model. The effectiveness of the CMP model is demonstrated experimentally.

View full abstract

Low side lobe level (SLL) and forming nulls can help to realize high-frequency (HF) superdirective receive arrays. In this letter, we reformulate the problem of designing an HF superdirective receive array as a problem of pattern synthesis. Based on the adaptive array theory, we present a numerical pattern synthesis algorithm combined with the design of HF superdirective receive array. Compared with the existing methods for superdirective array design, new method has more advantages in suppressing interferences and clutter. To confirm the effectiveness of novel method, numerical simulations are conducted.

View full abstract

A novel high-voltage trench gate insulated gate bipolar transistor with diffusion remnant (DR) layer (DR-IGBT) is proposed in this letter. The DR layer in the emitter side which is formed by grinding after ultra-deep N⁺ diffusion helps to stored the carrier and improves the on-state voltage drop (V_ce(SAT)). The DR-IGBT has a better trade-off between the breakdown voltage (BV) and V_ce(SAT) than the carrier stored trench bipolar transistor (CSTBT). The doping profile of diffusion remnant layer makes the junction of the p-base/DR layer nearly linearly graded junction, which does not decline the BV too much. The depth of the diffusion remnant layer and N⁺ diffusion layer less impacts BV and V_ce(SAT) unless the diffusion depth is reduced.

View full abstract

We propose a simple method for measuring the mode power of two-mode fiber based on the bending method. The mode power ratio is determined with better than 1dB accuracy by undertaking three power measurements with different numbers of fiber bends. We also evaluate the estimation error of the proposed method and the required resolution of the measurement.

View full abstract

High dv/dt caused by the fast switching of high voltage induces misfiring of adjacent power MOSFETs by a fluctuating gate voltage. This is known as the self turn-on phenomenon. The gate voltage of vulnerable power MOSFETs is increased by charging the Miller capacitance with the abrupt application of a drain voltage, even though the gate drive circuit maintains the off condition. This study analytically derives the model equation of gate voltage behavior and experimentally compares the difference in the phenomena between high-voltage Si super-junction MOSFETs and SiC MOSFETs on the basis of static C-V and dynamic characteristics. The results show that the gate voltage of SiC MOSFETs is insusceptible to a high-voltage fast switching operation.

View full abstract

This paper presents the electric shielding effectiveness (SE) of a dual metallic wall with narrow slots when the plane wave is incident. In the analysis, integral equations for aperture electric fields on slots are derived and solved by applying Galerkin’s method of moments (MoM). The numerical results show that plane-wave SE depends on both slot lengths and plate spacing for a given frequency. Plane wave SE fluctuates with the spacing of the plate, and the fluctuation period is about 0.5λ. A high level of electric SE can be obtained for small slots and low frequencies. Also obtained is the electric SE below 0dB when the plate spacings are smaller than 0.1λ. Experimental measurements are also presented to validate the theory.

View full abstract

In this letter, we calculated the propagation path loss because of the vertical electric dipole on perfect electric conductor ground in time domain. We derived the electric field in time domain and calculated the transient response and the received signal strength. The results show that the changes in the height of the base station caused the changes in the transient response in time domain and that such changes also affect the changes in received signal strength and the location of the near field because of the effects of ground surface. It is expected that such results can be applied in mobile communication network design and in military communication such as ground surface radars.

View full abstract

The shift register comprised of metal-oxide thin-film transistors (TFTs) is apt to exhibit anomalously high power consumption because the oxide TFT often has depletion-mode characteristic. We have developed a new shift register circuit in which one of the pull-down TFTs is controlled by capacitive coupling with the clock signal and the input carry signal. Employing this structure, the TFTs with non-zero V_DS are always turned off with negative V_GS. As a result, unnecessary current through the TFTs is eliminated and the power consumption of the new circuit decreases to the half of our previous one when the threshold voltage of the TFT is −5V.

View full abstract

Wide Single Instruction Multiple Data (SIMD) architectures are very important in the compute-intensive applications, but less efficient for applications with cross-iteration dependency loops which are difficult to parallelize and vectorize. This paper introduces Decoupled Iteration Mapping (DIM), a technique that dynamically maps a cross-iteration dependency loop onto the improved SIMD architecture which achieved multicore-like thread-parallel performance. The minor modification on the baseline architecture is composed of a Prefetch Unit & Instruction Buffer Array (PU&IBA), a Loop Control Unit & Instruction Dispatch Unit (LCU&IDU), and a Data Buffer Chain (DBC). Experimental results show that, the proposed DIM scheme can achieve average 3.04x performance speedup with a cost of only 6.44% area overhead.

View full abstract