Ship structures made of glass fiber-reinforced polymer (GFRP) composite laminates are considerably thicker than aircraft and automobile structures and more likely to contain voids. The production characteristics of such composite laminates were investigated in this study by ultrasonic nondestructive evaluation (NDE). The laminate samples were produced from E-glass chopped strand mat (CSM) and woven roving (WR) fabrics with different glass fiber contents of 30–70%. Approximately 300 pulse-echo ultrasonic A-scans were performed on each sample. The laminate samples produced from only CSM tended to contain more voids compared with those produced from a combination of CSM and WR, resulting in the relative density of the former being lower than the design value, particularly for high glass fiber contents of ≥50%. The velocity of the ultrasonic waves through the CSM-only laminates was also lower for higher glass fiber contents, whereas it steadily increased for combined CSM–WR laminates. Burn-off tests of the laminates further revealed that the fabric configuration of the combined CSM–WR laminates was of higher quality, prevented the formation of voids, and improved inter-layer bonding. These findings indicate that combined CSM–WR laminates should be used to achieve more accurate ultrasonic NDE of GFRP composite structures.

A wideband low‐noise amplifier (LNA) for long‐term evolution applications is presented. A capacitive cross‐coupled common‐gate in combination with current‐bleeding common‐source topologies is adopted for wideband input matching, high gain and low noise figure (NF). Inter‐cascade inductors are adopted to cancel the inter‐stage parasitics, which extend input matching and operational bandwidth to higher frequency with additional NF reduction. Implemented in a 0.18 µm CMOS technology, the proposed wideband LNA shows a voltage gain of 17 dB, a NF of < 2.5 dB, | S ₁₁ | of higher than 10 dB and a maximum IIP3 of + 1.52 dBm over the frequency range of 0.7–2.7 GHz while consuming 7.5 mA from a 1.8 V supply.

Glass fiber-reinforced polymer (GFRP) ship structures are generally fabricated by hand lay-up; thus, the environmental factors and worker proficiency influence the fabrication process and presence of error in the non-destructive evaluation results. In this study, the ultrasonic testing of GFRP hull plate prototypes was conducted to investigate the statistical significance of the influences of the design parameters, e.g., the glass fiber weight fraction (Gc) and thickness variations, on the measurement error. The GFRP hull plate prototypes were fitted with E-glass fiber chopped strand mats (40 wt % content) with different thicknesses (7.72 mm, 14.63 mm, and 18.24 mm). The errors in the thickness measurements were investigated by conducting pulse-echo ultrasonic A-scan. The thickness variation resulted in increased error. Furthermore, hull plate burn-off tests were conducted to investigate the fabrication qualities. Defects such as voids did not have a significant influence on the results. The statistical analysis of the measurement errors confirmed that the thickness variations resulted in a strong ultrasonic interference between the hull plates, although the hull plates had similar specific gravity values. Therefore, the ultrasonic interference of the layer group interface should be considered to decrease the GFRP hull NDE errors with respect to an increase in the thickness and Gc.

A full frequency band active RF tracking filter design for a digital TV tuner is implemented for the first time. By combined control of the G_m and C values in the biquad of the G_m-C filter, the proposed tracking bandpass filter satisfies full frequency band tuning while maintaining narrow bandwidth. The G_m cell of the tracking filter is based on a dynamic source degenerated differential pair with optimised transistor size ratio, which provides good linearity and high-frequency operation. The fabricated tracking filter based on a 0.13 µm CMOS process shows 48–780 MHz tracking range with 15–60 MHz bandwidth, more than 50 dB of third-order harmonic rejection, 14 dB unwanted signal rejection at N+6 channel offset, and a maximum IIP3 of 3.8 dBm at 4.7 dB gain while drawing 30 mA from a 1.2 V supply.