A novel compact multiband microstrip EMI filter based on metamaterials is presented. The filter is implemented by means of split-rings resonators and complementary spiral sub-wavelength resonators, conveniently coupled to the victim transmission line. The suitable combination of these resonators allows us to design several stop-band frequency responses located at 900MHz (RFID UHF), 1.8GHz (GSM) and 2.4GHz (ISM) with a significant rejection level. A 3-stages/5-stages rejection band filter has been designed and fabricated in a PCB. The experimental results show a significant rejection level in agreement with the electromagnetic simulations.
This work describes a novel transparent micro-needle array for photodynamic therapy (PDT) applications. This micro-needle array, with 250um in height and 35um in diameter, was placed onto skin and penetrated the cuticle yet not reaching the corium layer, so as to avoid pain and bleeding but achieve superior light transmission efficiency. For PDT applications, this design can significantly reduce the required incident power and therefore avoid additional damage to surrounding healthy tissue. Practical in-vivo test on human skin demonstrates the improved power transmission efficiency (PTE) of two types of needle arrays is 1.41 and 1.71 times better than the condition without using micro-needle array.
Image moments that are invariants to distortions such as translation, scale and rotation are an important tool in pattern recognition. In this paper, derivation of invariants for Tchebichef moments with respect to rotation will be presented. The rotational invariants are achieved neither by tempering with the image nor transforming the coordinates from rectangular to polar. They are derived using moment normalization method, which attempts to map the distorted moments with the undistorted ones. Experimental results show that the derivation is correct and it poses as a viable solution to test whether one image is a rotationally distorted version of another.
In the present paper, we propose a method of reference signal extraction for a semi-adaptive sound reproduction system based on semi-blind source separation under a noisy environment. Since the fluctuation of room transfer functions degrades the reproduced sound, we have proposed a semi-adaptive sound reproduction system that updates the inverse filters. However, in a noisy environment, it is difficult to observe only the reference signal. Therefore, we use semi-blind source separation to obtain a clean reference signal from a noisy observed signal. The simulation results reveal that the proposed method can obtain the reference signal with high accuracy.
This paper presents a new bilateral filter (BF)using the adaptive standard deviation based on the target similarity index (TSI) for small target detection. At first, the threshold value of pixel's TSI in window decides whether any pixel is a potential small target or not. The TSIs of the potential small target pixels are mapped to standard deviations of domain and range filters of the BF by linear mapping and the two standard deviations increase in proportion to the TSI for blurring the small targets. For the more blurred small targets, the filter size according to the TSI is increased. Experimental results demonstrate that the proposed method is more robust and efficient than the conventional methods.
In this paper, a mathematical design for dual-band matching of arbitrary impedances is presented based on Composite Right/Left Handedness (CRLH) and conventional transmission line theories. This design process of transforming arbitrary impedances to 50 ohms at two frequencies suggests an analytic approach to dual-band matching for multi-band devices. As well, bandwidth analysis of the proposed method is presented for wideband applications. For the verification, CRLH transmission lines were built successfully to match the output impedances of a commercial transistor at 824MHz and 2.5GHz. This work is expected to be useful for the extraction of general solutions for the dual-band matching network of arbitrary impedances.
A left-handed transmission line with regularly spaced Schottky varactors is experimentally characterized. Due to dispersion, an envelop pulse on the line experiences a great distortion. By measuring the test line, we successfully observed that this distortion is compensated for by the nonlinear effects of Schottky varactors. This article describes the experimental observations, together with fundamental properties and numerical performance prospects of the line.
A new technique to adjust the duty cycle of the output clock by adopting a pulsewidth control loop (PWCL) in dual-slope combination is presented. Correcting both rising and falling slopes simultaneously in their combination leads to a simple way for a wide correction range. Furthermore, the duty cycle can be easily adjusted to a desired value by setting up the programmable current sources in the charge pump. A generic circuit is suggested, and its validity is verified in a 0.13-µm CMOS technology under 1.2V supply. The simulated results with Spectre exhibit the integral nonlinearity (INL) of less than 2% for the output duty-cycle range from 6.25% to 93.75% with the consideration of process, voltage, and temperature (PVT) variation.
This paper proposes implementation of digital signal processor (DSP) to perform flexible-band digital hysteresis current control in a switched capacitor active power filter (SCAPF). By integrating hysteresis current control with digital-based neural network harmonic detection, the proposed SCAPF forces the supply current to be sinusoidal, to have low current harmonics, and to be in phase with the line voltage. Simulation on MATLAB Simulink verified the controller's algorithm design, and a purpose-built laboratory SCAPF system tested its feasibility.
A hardware architecture that implements an adaptive filter based on energy analysis of radar echoes to improve the detection of the Constant False Alarm Rate (CFAR) algorithm is presented. Signal processing based on energy analysis emphasizes the edge of the echoes improving the performance of the detection process. The energy filter coefficients and CFAR parameters are calculated adaptively by the architecture, reconfiguring the block of coefficient weights according to environment conditions. The architecture accelerates the data processing by a pipeline structure and sliding window for the coefficients convolution with data, resulting in high performance operation. Results of implementing the architecture in a FPGA device are presented and discussed.
A fast-lock and portable all-digital delay-locked loop (ADDLL) with 90° phase shift and tunable digitally-controlled phase shifter (DCPS) for DDR controller applications are presented. The ADDLL can achieve small phase-shift error in 1.3° at 400MHz and locking time of less than 13 clock cycles, making it very suitable for low-power DDR controller with power-down mode. The proposed DCPS provides the suitable phase shift of control signals for DDR interface where precise control is the key to reliable high-performance operation. Besides, the cell-based implementation makes it easy to target a variety of technologies as a soft silicon intellectual property (IP).
We discuss the stability of an adiabatic stepwise-charging circuit with advanced series capacitors, which is effective for the reduction of the applied voltage to each capacitor. SPICE simulation shows that this circuit is stable even if the initial voltages are lower than zero. For the analytical discussion, we derive a matrix that connects charge and voltage in the circuit and show that the matrix is a positive-definite symmetric one. Therefore, the step voltage is generated spontaneously. We also derive energy dissipation analytically using tank capacitor voltage. Using this formula and SPICE simulation, we clarify that energy dissipation decreases monotonically as a function of time and finally reaches the minimum value.
In mobile communications in urban area, it is a significant problem that blind spots of in the narrow street are caused by high buildings. In this research, a new dual-antenna system is proposed, including a receiving and a reradiating antenna and feeding networks to realize a broad-angle beam control. An equivalent bistatic radar cross section (BRCS) is deduced to evaluate the antenna performance. The main advantage of this design over ordinary reflectarray antenna as a passive RF booster is its flexible beam control capabilities.
In power-efficient WLAN/cellular dual mode mobile station (MS), WLAN interface is basically turned off when it is not actively transmitting or receiving data because idle state power consumption of WLAN interface is significant and it is much higher than that of cellular interface. Since only cellular interface is turned on to maintain reachability, if a VoIP call is arrived at WLAN it is notified through less power-consuming cellular interface. The paging via cellular interface for VoIP call, however, generates significant signaling load at radio interface because paging has to be performed to all cells within a registered cellular registration area (RA). In this paper, we reduce signaling load of power-efficient WLAN/cellular networks by paging cells only containing WLAN using the network coverage information between WLAN and cellular network, without degrading the performance of power consumption. Numerical results show that the signaling load of power-efficient integrated WLAN/cellular networks is significantly reduced.
We demonstrate an 850-nm high-speed photoreceiver with a monolithically integrated silicon avalanche photodetector for optical interconnect applications. The photoreceiver is fabricated with standard 0.25-µm SiGe bipolar complementary metal-oxide-semiconductor technology without any process modification. The photoreceiver achieves 7-Gb/s optical data transmission with the bit-error rate less than 10-10 at -1dBm incident optical power.