In this paper, we present a selective scan slice encoding technique for power-aware test data compression. The proposed scheme dramatically reduces test data volume via scan slice repetition, and generates an adjacent-filled test pattern known as the favorable low-power pattern mapping method. Experiments were performed on the large ITC'99 benchmark circuits, and results show the effectiveness of the proposed method.
This paper investigates the use of ultrasonic second harmonic components in the quality control of bolt fastened structures. The second harmonic components from a fastened bolt were detected using a double-layered piezoelectric ultrasonic transducer (DLPT). The fundamental ultrasonic pulse waves (1MHz) are transmitted when the DLPT is electrically connected in parallel, while the second harmonic ultrasonic components (2MHz) are detected when the DLPT is connected in series. A hexagon head bolt (the diameter and length of the screw are 12mm and 100mm) was used in the experiments. The bolt was fastened by a torque of 40N-m. The second harmonic component increased by approximately 10dB before and after the bolt was fastened.
A fast delay search algorithm for time-domain equalizers (TEQs) in multicarrier communication systems is proposed. The algorithm simplifies the delay optimization process required in computing the TEQ tap weights, thus enabling TEQs to adapt quickly to channel variations. Simulation results show that the proposed delay search algorithm can reduce the TEQ's computational time significantly while maintaining comparable performances.
Some new realizations of third order lowpass (LP) Butterworth filters using the current differencing buffered amplifier (CDBA) and current feedback amplifier (CFA) type unity gain cells are presented. The circuits are practically active insensitive to the decvice port tracking errors (ε). Effects of the device parasitic capacitances on the nominal design are insignificant which can be conveniently compensated. With suitable design alternate bandpass (BP) Butterworth characteristics may also be obtained.
Single-channel speech dereverberation has been a challenging problem. In this letter, we describe a frequency-domain algorithm which efficiently estimates an acoustic reverberation filter to dereverberate speech by using its inverse filter. Since a reverberation filter is generally much shorter than the corresponding dereverberation filter, the algorithm may converge into a more exact filter and remove reverberant components better than the conventional methods. Simulation on noisy reverberant speech illustrates that the described method can improve speech dereverberation performance in comparison with the method which estimates a dereverberation filter.
A linear endfire wideband series fed double-dipole antenna array with low sidelobe level, SLL, and high front to back ratio, F/B, is proposed. The array can provide -27dB SLL at centre frequency of 16.26GHz, 20dB SLL bandwidth of 9.2%, 22dB F/B and 14.6% impedance bandwidth. By extending, in between the array elements, comb like linear tapered narrow strips from the finite ground plane of the structure, SLL of the basic array improves to -32dB, the 20dB SLL bandwidth become 12.1% while the F/B and impedance bandwidth remains the same as before. To verify the accuracy of the simulation results, both of the arrays are fabricated and tested.
Calibration of electric field probes in a GTEM cell is carried out using the reference antenna method. To determine the effectiveness of the calibration, we compared our results with those of calibration in an anechoic chamber from 1 to 6GHz. Each electric field probe had three elements, one of which was used to calibrate the other two. The calibration factors in the GTEM cell agree well with those in the anechoic chamber. Therefore, the GTEM cell is as effective as the anechoic chamber for calibrating electric field probes with the same type of probe and helps save more measurement time and effort.
The electronically tunable oscillator with a single-output and a multiple-output transconductor and with three passive grounded elements is presented and verified in this paper. The active elements are modeled on the transistor level for the possibility to implement the whole oscillator on chip. The characteristic equation and condition for oscillation are discussed together with the major influence of the parasitic properties of the active devices. Using the proposed concept an experimental verification employing two commercially available transconductance amplifiers is given via associated time-domain and frequency-domain results.
A wide band low actuation capacitive coupling electrostatic RF MEMS switching device is presented in this paper. The device includes a pi-shaped matching architecture containing two switches connected by a high impedance short transmission line. The device can act as a switch for any desired frequency whilst requiring only 12volts for actuation. By optimizing the length and the characteristic impedance of the transmission line, the switch can be tailored for desired frequency bands. The switch is calculated and simulated for Ka to V frequency bands demonstrating excellent improvements of RF characteristics.