The Equivalent Circuit Modeling Of Fluid Field

With the development of MEMS design technology, the finite element analysis is less able to satisfy the integral CMOS-MEMS design. It is necessary to realize system level simulation and analysis for the design and optimization of the device. Establishing the equivalent is one of the most important methods of system level simulation. In this paper, based on the physical characteristics of device working in fluid field, research a new method to build equivalent circuit, establish the equivalent circuit model of squeeze film damping effect and wind speed sensor temperature field innovatively.Different from the traditional electromechanical analogy, this paper proposes a new structure of coupling inductance matrix unit to establish the equivalent circuit, which is suitable for the distributed parameters. The circuit includes the primary inductance loop and the secondary loop unit matrix based on the theory of transformer principle. The voltage ratio distribution on both ends of the inductance in the secondary loop matrix and primary loop is compared to the distribution of distributed parameters in fluid field by analogy, thus fluid domain problem can be converted to electricity domain problem.Squeeze film damping effect influences the dynamic characteristics of the MEMS device. Structure under vertical movement makes the pressure distribution of the air under the thin film, which will be replaced directly by the voltage distribution in the matrix form. For square film and double-clamped beam, the pressure distribution of the air layer has different representation form and calculation method. Modeling the equivalent circuit of these structures' squeeze film damping effect, therefore, the fluid field behavior is characterized by the model, can be seamlessly connected to the external circuit and realize system level simulation. Different from traditional finite element analysis or the equivalent damping coefficient analysis, the method used in this paper of fluid field on damping analysis, is close to the finite element analysis in precision, close to the equivalent damping coefficient analysis in efficiency.Compared with symmetrical temperature distribution in no wind condition, the anemometer reaches a new heat balance with the uneven temperature gradient caused by the wind blowing over the surface. Analyze the surface temperature distribution of one dimensional sensor working in constant temperature difference control mode, and derive the two-dimensional sensor surface temperature. Using coupling inductance matrix circuit method to model the temperature field, compared with the experimental results, we found a good match; hence verify the feasibility of equivalent circuit modeling method.The fluid field modeling of MEMS devices is simulated under the SPICE software, which can be input by netlist file. Combined with MATLAB programming, the circuit parameters change and the simulation results extract can be automatic and simple. The new method to model the equivalent circuit of fluid field provides a new technical route on system level simulation problem solving.