Showing papers by "Jingfu Bao published in 2010"
08 May 2010
TL;DR: In this paper, a nonlinear model of LC oscillator is presented which is based on electrical parameters of circuit and the physical process that transforms device noise in transistors or resistors into phase noise by nonlinear spectrum conversion and linear spectrum shaping.
Abstract: A novel nonlinear model of LC oscillator is presented which is based on electrical parameters of circuit. In view of the operation condition of device in steady-state oscillation, we discuss the physical process that transforms device noise in transistors or resistors into phase noise by nonlinear spectrum conversion and linear spectrum shaping. A closed-form expression is derived for the output phase noise spectrum. This model is validated by simulation of a 2.9GHz Colpitts oscillator using ADS. Theoretical analysis and simulation shows that phase noise performance in LC oscillator can be improved by diminishing the feedback factor.
6 citations
08 May 2010
TL;DR: In this article, an equivalent circuit model for the unit cell of RF MEMS distributed phase shifter with MAM (Metal-Air-Metal) capacitor was proposed, which could predict the performance accurately.
Abstract: This paper advances the equivalent-circuit model for the unit cell of RF MEMS distributed phase shifter with MAM (Metal-Air-Metal) capacitor, which could predict the performance of the unit cell accurately. Based on the equivalent-circuit model, the dependence on fabrication process of the designed unit cell of RF MEMS distributed phase shifter is reduced very much. The maximum phase deviation of the unit cell is smaller than 0.829°even when fabrication errors reached 13%. The return loss of the unit cell is below −20dB and the worst insertion loss is −0.08dB at 10GHz. The MEMS bridge with elastic bending beam is actuated with actuation voltage 20 V. By adopting a novel topology to diminish coupling of different bits, 5-bit RF MEMS distributed phase shifter results in an average return loss of 13.56 dB, an average insertion loss of 1.49 dB, an average phase deviation of 3.17° and an average relative phase error of 2.24% at 10GHz.
5 citations
28 Jul 2010
TL;DR: In this paper, a 5-bit distributed MEMS phase shifter using meander structure is presented, making full use of common ground plane, the area is reduced to 5.36 mm*4.72 mm.
Abstract: Based on analysis of coupling between two adjacent lines with common ground plane, a novel 5-bit distributed MEMS phase shifter using meander structure is presented. Making full use of common ground plane, the area is reduced to 5.36 mm*4.72 mm. Compared to 5-bit distributed phase shifter using conventional structure, the length of advanced phase shifter is decreased by 70%. The phase shifter is formed by two kinds of unit cells which are respectively linear unit cell and unit cell with right angle bend. The return loss of the linear unit cell which achieves phase shift of 11.25° is below −20dB and the worst insertion loss is −0.083dB at 10GHz. At the same time, the designed unit cell with right angle bend which obtains phase shift of 22.5° shows return loss of −17.11 dB, insertion loss of −0.27 dB and in the worst case at 10GHz.
2 citations
08 May 2010
TL;DR: In this article, a low loss 8-10 GHz tunable filter using high-Q RF MEMS capacitance networks is proposed and discussed, which utilizes admittance matrix of the filter network.
Abstract: This paper presents a low loss 8–10GHz tunable filter using high-Q RF MEMS capacitance networks. An improved design method, which utilizes admittance matrix of the filter network, is proposed and discussed. Detail design equations for the tuning elements and coupled microstrip λ/2 resonators are given. Compared to previous method, this method is improved since it is applicable to not only symmetric filter network but also asymmetric ones. To verify this method, an 8–10GHz tunable filter is designed and simulated. The simulation results obtained by 3D electromagnetic simulation tool are in good agreement with the results calculated by the proposed method.
1 citations
28 Jul 2010
TL;DR: In this article, an equivalent circuit model of MAM (metal-air-metal) capacitor applied in RF MEMS devices is proposed and the parametric analysis of the proposed models and the designing method are also presented.
Abstract: In this paper, an equivalent- circuit model of MAM (metal-air-metal) capacitor applied in RF MEMS devices is proposed. Also, equivalent-circuit model of distributed MEMS phase shifter with MAM capacitor are presented. The parametric analysis of the proposed models and the designing method are also presented. By adopting the unit cell (0/11.25°) of 5-bit X-band distributed phase shifter, the paper discusses the model error and the efficiency of the proposed equivalent-circuit model. Compared with existing equivalent-circuit model, as for S 11 , the model error of the proposed equivalent-circuit model could be less than 1dB, decreased by about ten times, and the model error for phase shift per unit cell could be less than 0.5°, decreased by about thirteen times.
1 citations