Although many modeling approaches exist for analyzing the behavior of capacitive micro-machined ultrasonic transducers （CMUTs）, the relation equation between the design pa- rameters with input and output is still la...Although many modeling approaches exist for analyzing the behavior of capacitive micro-machined ultrasonic transducers （CMUTs）, the relation equation between the design pa- rameters with input and output is still lacking. What there is can only be used to analyze the dynamic performance of CMUT indirectly and qualitatively, such as stiffness and sound pressure. A lumped-parameter theoretical model based on the dynamic theory is proposed in this paper. The relation equations between the design parameters with inputs and outputs are given. The results obtained by the proposed model agree well with those by finite element method （FEM） simulation. The dynamic and static behavior of CMUT can be clearly depicted, which is helpful for design and optimization iterations. This shows that the proposed model makes it easier to optimize the parameters of a CMUT with respect to output and bandwidth directly and to better understand the influence of each parameter.展开更多
This paper presents the design and implementation of a current self-adjusted VCO with low power consumption. In the proposed VCO, a bottom PMOS current source instead of a top one is adopted to decrease the tail noise...This paper presents the design and implementation of a current self-adjusted VCO with low power consumption. In the proposed VCO, a bottom PMOS current source instead of a top one is adopted to decrease the tail noise. A current self-adjusted technique without additional external control signals is taken to ensure the VCO starts up in the whole band while keeping the power consumption relatively low. Meanwhile, the phase noise of the VCO at the low frequency （high Cvar） can be reduced by the technique. The circuit is implemented in 0.18 μm CMOS technology. The proposed VCO exhibits low power consumption of 〈1.6 mW at a 1.5 V supply voltage and a tuning range from 11.79 to 12.53 GHz. The measured phase noise at 1 MHz offset from the frequency 11.79 GHz is-104.7 dBc/Hz, and the corresponding FOM is -184.2 dBc/Hz.展开更多
基金Project partially supported by the following foundations:the National S&T Key Project in China (No. 2009ZX03006-001-01)the Fundamental Research Program of Shenzhen (No. JC201005270363A)the Key Project of Fundamental Research Program of Shenzhen (No. JC201104220265A)
文摘Although many modeling approaches exist for analyzing the behavior of capacitive micro-machined ultrasonic transducers （CMUTs）, the relation equation between the design pa- rameters with input and output is still lacking. What there is can only be used to analyze the dynamic performance of CMUT indirectly and qualitatively, such as stiffness and sound pressure. A lumped-parameter theoretical model based on the dynamic theory is proposed in this paper. The relation equations between the design parameters with inputs and outputs are given. The results obtained by the proposed model agree well with those by finite element method （FEM） simulation. The dynamic and static behavior of CMUT can be clearly depicted, which is helpful for design and optimization iterations. This shows that the proposed model makes it easier to optimize the parameters of a CMUT with respect to output and bandwidth directly and to better understand the influence of each parameter.
基金Project supported by the Project on the Integration of Industry,Education and Research of Guangdong Province,China(No.2012B090600035)
文摘This paper presents the design and implementation of a current self-adjusted VCO with low power consumption. In the proposed VCO, a bottom PMOS current source instead of a top one is adopted to decrease the tail noise. A current self-adjusted technique without additional external control signals is taken to ensure the VCO starts up in the whole band while keeping the power consumption relatively low. Meanwhile, the phase noise of the VCO at the low frequency （high Cvar） can be reduced by the technique. The circuit is implemented in 0.18 μm CMOS technology. The proposed VCO exhibits low power consumption of 〈1.6 mW at a 1.5 V supply voltage and a tuning range from 11.79 to 12.53 GHz. The measured phase noise at 1 MHz offset from the frequency 11.79 GHz is-104.7 dBc/Hz, and the corresponding FOM is -184.2 dBc/Hz.
