Applied Mechanics and Materials Vols. 303-306

Abstract: At present, cable transmission is used mostly in the coal mine safety production monitoring. Cable transmission mode has many shortcomings, for example: wiring complex, line dependence of strong, installation and maintenance cost more. Badly working conditions of coal mine underground increase the difficulty of the wiring. In order to solve the cable transmission mode existing problems and the insufficiency, this paper analysis wireless sensor node which use in the coal mine underground and the functions of its modules characteristics and performance requirements deeply .And design wireless sensor node of coal mine based on STM32W108 chip, research emphatically each function module of the working principle. It also presents the hardware platform of the overall design scheme and hardware circuit diagram and software flow chart.

Abstract: A Novel CMOS reconfigurable mixer for dual-mode GNSS receiver is proposed in this paper, this mixer consists of a Gilbert mixer with a reconfigurable matching network, it can be used for both USA GPS and China Beidou receiver systems, simulation results shown the configurable mixer has a voltage conversion gain 20.5dB in the interested frequency bands, the S11 parameter is around -18dB at both GPS and Beidou frequency bands, the circuit draws 7.3mA current from 1.8V power supply.

Abstract: This paper presents a modified preamplifier-latch comparator for minimum latch delay and minimum input referred noise. The ratio of PMOS/NMOS in cross-coupled inverter is verified theoretically and optimized for minimum comparator delay. The cross-coupled load, the cascaded structure and the capacitor neutralization techniques are adopted to reduce the kickback noise and the input referred offset voltage. The comparator circuit is designed in a TSMC 0.35 um/3.3 V 2P4M CMOS process. Simulations show that the delay time of latch is declined by 18 percent after optimization and the maximum transfer delay time is only 384.5 ps. The peak to peak value of kickback noise is only 0.831uV in case of Vin,max=1.25 V, and the Monte Carlo simulation results show that equivalent input referred offset voltage is 4.56mV.

Abstract: An improved phase comparator solution for the fast-locking all digital SARDLL, which can deal with the irregular clock signal and give the signal Comp reflecting the phase relations between input clock and output clock, and the signal LD indicating whether the DLL is locked or not, is presented. The improved solution is justified by the transistor- level post-layout SPICE simulation results.

Abstract: This paper introduces an improved SPICE model of memristor using dependent sources and switches. The proposed SPICE model with two parameters in dependent current source has ideal frequency and amplitude characteristics. We simulate two circuits with memristor. The results demonstrate that the memristor can “remember” last resistance value when no current passes through it, the Amplitude Modulation (AM) circuit with memristor and op-amp is simulated under the condition of high frequency. Since the memristor has great performance in frequency there might be a possible application of the memristor to be used as modulator or demodulator in wireless communication.

Abstract: By combining the method of moment (MoM) and the method of network analysis, we analyze the microstrip filter circuits. First, we deduce and calculate the closed form multilayered Green’s function by using the discrete complex image method. Then, we apply the multilayered Green’s function into the method of moment (MoM) and by using the multi-port network theory, we get the networks parameters. At last, the numerical result proves the method’s accuracy and validity.

Abstract: This paper first reviews the polyphase filter in the decimation and interpolation application, and simply introduces the multi-rate system. And then through the simulation experiments, the characteristics of the sub-filter of the polyphase filter were analyzed. Finally, according to the characteristics of the sub-filter, this paper presents an application in multipath delay.

Abstract: A design method of the digital signal generator, based on LPC2132 as the master control chip, is introduced in this paper. The system has used of a chip of the direct digital frequency synthesizer (DDS) and a complex programmable logic device(CPLD) to produce the sine wave, square wave and triangle wave, and has designed circuits of analog signal amplification and gain control. Realized the switch of different signal through the keyboard, it is a new kind of the digital signal source, which has performances including stabilizing waveform, higher precision, adjustable amplitude and frequency on the permitted scope.

Abstract: Abstract: In this paper, the working principle of the Direct Digital frequency Synthesis (DDS) technique is briefly introduced. The main source of the spurious output is analyzed. After derived how to reduce the spurious signals, an improved DDS based on Amplitude to Phase sampling is proposed. It can decrease the phase truncation error to improve the frequency stability, reduce the phase quantization error, and save storage space. In the end, the simulation results display the performance of this DDS system.

Abstract: To achieve fast charging of lithium battery, based on MSP430 microcontroller, an intelligent Li-ion battery charging system was designed with voltage and current detection function. By collecting voltage and current values and making judgment on charging states of batteries, Pulse Width Modulation signal (PWM) was adjusted to realize high-precision charging control. The unit modules and their driving software flow chart were presented. The experiment results show that the charging system takes only 1 hour for a lithium battery to be charged. The system is faster than ordinary chargers which need 2-3 hours to finish charging. So the charging system shortens the charging time effectively.