Applied Mechanics and Materials Vols. 130-134

Abstract: This paper improves the broadband equivalent circuit model (ECM) modeling method of Electro-absorption Modulator. According to the principle of Circuit Partitioning Simplified, the series form of the original increased frequency impedance model is transformed into the parallel form. The result shows that the new method eliminates the process of the impedance type verification, will not introduce new nodes, and reduces the computation. After testing, the maximum relative error of this model to fit measurement data is only 0.693%. This method’s simulation results are consistent with the test data of ECM better in 0-8GHz frequency range.

Abstract: In TD-SCDMA trunking system, imperfect power control and user mobility are disadvantages for the capacity and performance of the system. In order to meet the requested Quality of Service (QoS) of group users, in this paper, we introduce a congestion control mechanism in downlink for TD-SCDMA trunking system. The mechanism is based on Adaptive Multi-Rate (AMR) mode selection and interrupt connections of users, analyzed in detail and verified by using MATLAB to structure a dynamic system level simulation platform. The simulation results reveal that system performance can be significantly improved.

Abstract: A 3.1 ~ 10.6 GHz Ultra-Wideband SiGe Low Noise Amplifier (LNA) is proposed. This low noise amplifier utilizes a current-reused technique to increase the gain and extend the bandwidth. We have a detailed analysis for the input matching, noise figure, gain and other features. The LNA was designed with the TSMC 0.35µm bipolar silicon-germanium (SiGe) processes. Simulation results show that the input reflection coefficient is less than-9dB, the output reflection coefficient is less than-10dB, the maximum power gain of 17 dB and the minimum noise factor (NF) of 2.35dB. The total power consumption is 6.2 mW with 2.5V power supply.

Abstract: A novel dual-mode bandpass filter using defected microstrip structure with distributed capacitance loading inside the free area of a defected microstrip dual-mode loop resonator is proposed in this paper. The filter has the advantages of compact size together with sharp rejection of out-bands and a wide stop-band. The measured results show that better than 20dB rejection levels in the stop-band up to 4.25 GHz have been obtained. It has been validated by simulation and experiment. The simulated results are compared with measured data and a good agreement is achieved.

Abstract: In the framework of regularization process for quantization, the mesoscopic open electron resonator is quantized using Feynman’s path integral method. With a Gaussian type propagator, the energy spectrum and wave functions are calculated. As an application of the results, the quantum fluctuations and uncertainty relation are discussed. The detailed formulation of energy spectrum and wave functions would be benefit to the further research work of the system.

Abstract: This paper presents the design and fabrication of a compact 4-8GHz sweep frequency source at C-band with a hybrid frequency synthesizer technology. With DDS used as PLL’s reference, the frequency step size is as small as 3×10^-4 Hz and the measured 1 kHz offset phase noise is-91.79dBc/Hz at 4GHz. This frequency sweep source has advantages of wide bandwidth, low phase noise, small frequency step size, low spurious, fast tuning speed, small size and low power consumption. So it is suitable for wireless hand-held test equipment and communication equipment.

Abstract: A 2.4GHz high linearity downconversion mixer is designed with MOSFET transconductance linearization technique. Multiple gated transistors (MGTR) (or derivative superposition) method is adopted in the structure to increase IIP3 of the mixer as well as its convertion gain isn’t degraded. In order to improve the performance of the mixer further, a LC tank is used in the LO stage and two current steering PMOS transistors in load stage. The Mixer is design in TSMC 0.35um SiGe BiCMOS technology. Simulation results show that the mixer achieves 2.88dBm input 1dB compress point, 16.18dBm third-order input intercept point (IIP3) and the conversion gain is 12.97dB.

Abstract: This paper presents the design and implementation of a C-band 6-8 GHz wideband low noise amplifier (LNA). The design is based on balanced structure. The compensated matching networks are designed to obtain gain flatness, two Wilkinson couplers are used to obtain good input and output VSWR, a section of microstrip line is introduced between the source and ground to improve the stability. The measured gain is 12±0.5 dB and noise figure is less than 1.5 dB, the input and output VSWR are better than 1.7. The LNA with broad bandwidth, flat gain, low noise figure and high stability can be used in wideband RF receivers.

Abstract: With the accelerating construction of strong smart grid, and the grid voltage level rising, performance requirements for the electrical insulation of electrical equipment also continue to increase. In terms of the advantages of RTV on antifouling, RTV-based paints coated insulator coating capacity of its flash tolerance can significantly increase, mainly due to RTV coating hydrophobic hydrophobicity and migration. But when the hydrophobic surface is in the fully wet, many small drops of water in the surface will be gathered into big drops of water, and these large droplets will distort the surface electric field of the medium. So the flashover voltage of the hydrophobic surface’s separated water droplets under DC electric field are analyzed comparatively in this paper, while some influencing factors such as different medias and volume of water drops, are introduced in specific experiments, and their effects on the flashover voltage are analyzed; under DC electric field experiment on the surface of hydrophobic and hydrophilic surface flashover voltage drops separation characteristics were studied.

Abstract: A mathematical model for the output waveform of SPWM VSI (voltage source inverter) is created specific to the harmonic problem of SPWM voltage source inverter. Through theoretical analysis and calculation, we can get the distribution regularity of the output harmonic wave in the process of frequency conversion and voltage transformation. Utilizing the matlab to verify the simulation, we can get such results like “frequency conversion will lead to the shift of the harmonic wave’s distribution center”, “voltage transformation will cause the valuable change of the harmonic wave and the valuable change direction of harmonic wave is opposite to that of the fundamental wave”. All of these will have significant guide meaning to the application of SPWM.