MEMS+® for MEMS+IC Co-Simulation in Cadence Virtuoso

Most MEMS are comprised of a MEMS sensing or actuation element (the “MEMS device”), which is distinct from the accompanying electronics (the “IC”) that process the output signal from the device and/or control the device. MEMS product development within any organization divides the development similarly: the MEMS engineers who design the MEMS device, and IC engineers who design the surrounding sensing or control electronics.

IC engineers commonly use Cadence Virtuoso to design the analog/mixed-signal electronics that accompany a MEMS device. In order to succeed, IC engineers require fast and accurate models of the MEMS device in the Cadence model library. The MEMS model is then used as a component in the IC schematic to perform MEMS+IC cosimulation. The co-simulation is essential to verify the IC design and to predict yield sensitivity to manufacturing variations.

The Coventor MEMS+ tool suite’s integration with Cadence facilitates the required model exchange from the MEMS engineer to the IC designer in a far more seamless manner than previously available in the marketplace. The generation of a Cadence library cell with both a parametric simulation model and layout Pcell is almost instantaneous and doesn’t require any FEM analysis or time-consuming reduced-order modeling. Using the MEMS+ import GUI in the Cadence Library manager, a “symbol view”, a “model view” and a “layout view” can be created automatically from any given Innovator schematic. The pages that follow describe the details of how Coventor has made this seamless integration possible.

Description of MEMS+ for Cadence
MEMS+ for Cadence Virtuoso is a design solution for a coupled MEMS+IC design flow. With MEMS+ for Cadence, designs created in MEMS+ Innovator can be automatically converted into IC compatible models and parametric layout (PCells) for the Cadence Virtuoso design environment. MEMS+ for Cadence supports MEMS+IC co-simulation in Spectre and SpectreRF. Simulation results can be loaded into the MEMS+ Scene3D module for 3-D viewing.

Features of MEMS+ for Cadence

  • Easy-to-use MEMS+ GUI in the Cadence Virtuoso Library Manager for automatic model and Pcell generation
  • User-defined number of symbol pins and parameters
  • Fast MEMS+IC circuit simulations
  • Accurate multi-physics modeling in Cadence simulators

MEMS+ Cadence Design Flow

The MEMS+ for Cadence design flow includes the following steps:

  1. Create a MEMS design in MEMS+ Innovator by selecting MEMS building blocks from the parameterized 3-D MEMS component library and assembling them into a MEMS device. As part of this process, the MEMS designer can specify which parameters will be exposed in the IC design environment.
  2. When the design is complete, import the Innovator schematic into the Cadence Library manager, which will automatically create a Cadence netlist and symbol. The number and names of the symbol pins are controlled by the MEMS engineer and represent electrical connections to the MEMS device.
  3. Place the MEMS+ symbol in a schematic in the Virtuoso Schematic Editor. For the MEMS designer, there may be only a few other components in the schematic necessary to provide electrical excitation, or electrical sensing of the output signal. For the IC designer, however, the schematic will include the complete IC design.
  4. Run a simulation or co-simulation in the Spectre circuit simulator. The simulator will connect, via the Cadence C Model Interface (CMI), with the MEMS+ component library to evaluate the MEMS behavioral model at each simulation point, i.e. time step or frequency.
  5. On completion of a simulation, view the simulation results for the MEMS device in the MEMS+ user interface. Within MEMS+, the user has the ability to animate the motion of the MEMS device.
  6. At any time, create a parameterized layout cell (PCell) that can generate a layout of the MEMS device.

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