With the development of semiconductor process technology and IC design technology, silicon-based filter technology continuously improved. The filter’s transmission characteristics depend on the dielectric constant, dielectric loss and substrate thickness. This paper studies the frequency response characteristics of transmission coefficient and reflection coefficient of the parallel coupled microstrip bandpass filter, in the condition of silicon-based with different thickness, loss and doped concentration, when the center frequency is 5.75 GHz.

Abstract. Liquid-metal direct writing is a cost-effective and green technology, which is very promising for the customized fabrication of flexible circuits and functional devices. However, owing to the high surface tension of metal ink, the printed circuits are prone to intermittent outflow, large forming size error, and unstable forming. The smooth flowing and conveying of liquid-metal ink are still huge challenges that need significant attention. Herein, the force mechanism of liquid-metal ink transported by ball rotation and translation of the printing head was analysed, and the wetting characteristics of liquid metal on the surface of different substrates and its influence on forming morphology were investigated. The stable output printing of gallium indium alloy (GaIn24.5) liquid metal was realized. The changing characteristics of the shape and size of the liquid-metal circuits formed under different printing speeds and writing pressures were experimentally studied. The effective process window for obtaining the best circuit quality was established. Based on this, a flexible printed circuit board and functional electronic pattern were successfully printed under the writing pressure W=1 N and printing speed F800 mm min−1. The printed lines of GaIn24.5 exhibited a smooth surface, uniform width, small size error, and ability to connect electronic components and conduct electricity. This research proposes a new technical approach for customized printing of personalized electronic circuits and has important application prospects in the future.

Information processing module, which includes fuel cell sensor circuit, pressure sensor circuit, heating and temperature sensor circuit and signal filtering amplifier, is the core of Intelligent Alcohol Tester. Its main task is to complete the collection and pretreatment of alcohol gas signal. In this paper, the hardware module is first simply introduced. And next, test method and the relevant criteria are done to prove that the modules have good accuracy and stability and achieve the requirements of alcohol tester.

We propose a DCT domain watermarking algorithm, this algorithm transforms the watermark image before the watermark embedding and embeds watermark images by key vector, which improves the robustness and security greatly. The experiments indicate that the program has a better robustness on Gaussian filtering, white noise, image shearing, so digital watermark technology is useful.

This paper introduces a kind of alcohol test system composed of hardware based on alcohol instrument, and software based on data management, which is the foundation of internet wireless technology transmission platform based on embedded web server. It can provide reliable wireless sensor networks and complete information integration and conformity through sites control platform, present wireless data transmission technology and data management system in order to achieve unified management of information and law enforcement. Practice shows the alcohol test system has obvious advantages with stability, high accuracy, and strong anti-interference.