MEMS Product Design Platform

Historically, MEMS designers have had very few alternatives for simulating the complex, physical behavior of their entire devices. MEMS designers have either used highly simplified “lumped mass” models, implemented in SPICE, or chosen accurate, but very time-consuming, finite element analysis (FEA). Neither of these choices, used separately and/or in combination, has provided an adequate solution to the growing problem of optimizing MEMS performance while meeting ever-decreasing time to market windows.

MEMS+® provides the best of both worlds: the accuracy of FEA with the speed of SPICE. Simulations run in minutes rather than hours or days, while capturing complex effects like cross coupling between mechanical degrees of freedom, substrate deformation, electrostatic spring softening, and quadrature effects in gyros. Hence, MEMS+ is ideal for designing and optimizing MEMS devices such as accelerometers, gyroscopes, resonators, switches, and optical mirrors that depend on electrostatics for actuation or sensing.

The parametric nature and speed of MEMS+ enables designers to rapidly explore manufacturing issues. Shown above are Sensitivity change and cross-axis sensitivity as a function of sidewall angle.

MEMS+ IC Design

In addition, MEMS+ enables a true top-down design methodology. To collaborate with their colleagues in control system design and IC design, MEMS designers no longer need to devote weeks or months to create hand crafted, reduced-order models based on analytical expressions and/or FEA extractions. Instead, they can immediately provide MEMS+ models for simulations of the complete system, i.e. the MEMS device plus electronics. Not only does this save valuable engineering time, but it eliminates manual handoff as a potential source of design errors. More importantly, the MEMS+ models fully capture the complex physical behavior of MEMS-based inertial devices, resonators, microphones, optical MEMS and more so that the surrounding electronics do not have to be over designed to compensate for unknown variability. MEMS+ models can be used early on, for algorithmic and control system design in Simulink, and for circuit design in Cadence. MEMS+ models can also be used for final design verification in Cadence prior to tape out.

With MEMS+, you can…

• Rapidly evaluate design concepts versus performance specification such as sensitivity, linearity, quadrature, bandwidth, and response time,
• Perform MEMS + IC system and circuit simulations, enabling design teams to optimize the MEMS device and circuit simultaneously
• Optimize designs for performance, temperature sensitivity, manufacturability, and yield,
• Simulate sensitivity, noise, linearity, dynamic range, for Microphones,
• Evaluate Package deformation issues simultaneously with the MEMS device
• Adjust DC bias to Match Sense and Drive Frequencies for Inertial Sensors
• Perform transient simulations which are completely impractical with FEA
• View 3D animations of mode shapes, harmonic response, and transient behavior

Cadence example schematic showing Microphone and output stage with Cadence Spectre sensitivity and noise response.

Cadence schematic for co-simulating the MEMS accelerometer with IC, with performance outputs such as linearity, sensitivity and bandwidth.