Page 57 - MEMS Mechanical Sensors

46 MEMS Simulation and Design Tools

Modal Analysis
Mode = 1
Frequency 318.5Hz

Z
Y

X

Figure 3.5 Modal analysis of a micromachined accelerometer using MemMech.

SimMan is a simulation manager that allows the users to set up a batch of solver
runs to view trends or the sensitivity to various design or manufacturing parameters.
Rather than manually adjust parameters and start individual solver runs, the Sim-
Man provides a variety of ways to set parameter variations automatically and iterate
solver results.
MemHenry is the inductance solver that computes the frequency-dependent
resistance and inductance matrices for a set of conductors. This tool is aimed at mag-
netic sensor design, on-chip passive inductor analysis, and parasitic extraction for
packaging analysis.
MemPackage is the package effects analyzer that computes the effects of pack-
age induced stresses and strains on a micromachined device mounted in a standard
or user-defined package.
MemPZR analyses piezoelectric effects created by electric polarization due to
mechanical stress and also addresses the converse, where strain in a piezoelectric
material develops due to the application of an electric field. It can handle large dis-
placements and other nonlinear effects introduced by electrical, mechanical, and
thermal loading. Also, it includes transient analysis and voltage-driven harmonic
analysis. Analyses necessary for obtaining S-parameters can be carried out, which
are especially relevant for RF devices such as bulk acoustic resonators.
MemETherm is an electrothermal solver that computes the potential drop
through a resistor resulting from a voltage and/or current flow and the resulting tem-
perature distribution from joule heating.
AutoSpring is a spring constant extractor that allows the extraction of multidi-
mensional, nonlinear spring behavior from complex tether designs. These values can
then be used for system level models.
MemDamping is the damping solver that computes the squeeze-film damping
and spring coefficients of a MEMS device using a hybrid Navier-Stokes-Reynolds
approach. Many physical MEMS sensors are sensitive to squeeze-film damping
effects—for example, this is one of most important features of the accelerometer
illustrated above. Figure 3.6 shows a typical output graph plotting the damping
coefficient of the accelerometer as a function of frequency.