A Single-Platform Simulation and Design Technique for CMOS-MEMS Based on a Circuit Simulator with Hardware Description Language

1. A Single-Platform Simulation and Design Technique for
CMOS-MEMS Based on a Circuit Simulator with Hardware
Description Language
BITS Pilani
Hyderabad Campus
Mayank Garg
2013H140040H
ME Embedded System

2. Motivation
 MEMS and CMOS technology has transformed the world
in last 3 decades.
 Most Of the MEMS today fabricated in the same way as
the silicon integrated system.
 Silicon in good for Both MEMS and CMOS.
 It is motivated us to integrate both the technology.
 Use of MEMS as important components and subsystems
in RF circuits has led a new dimensions in CMOS-MEMS
integration.
 A number of CMOS-MEMS devices have been fabricated
and delivered.
 Challenge in this is, CAD tool for co-design with MEMS
and CMOS integrated system need to be developed.

3. *
Design Flow
Flowchart based on circuit simulator
Electrostatic parallel-plate actuator.
Sub-Circuits for simulator
Verilog-A expressions
Result analysis
Comparison
Simulation and experiment result
Conclusion

4. System
specification
System
description
Mems
Circuit
Electrical
device
MicroMechanical
Device
MEMS
Layout
Fabrication
and Test

5. MEMS design flowchart based on mechanoelectric cosolver

6. MEMS design flowchart based on
mechanoelectric cosolver
MEMS design flowchart based on
circuit simulator with HDL
behavioral model

7. Analytical model for electrostatic parallel-plate actuator.

10. MODULE I: Sub-circuit model for the parallel-plate electrostatic
actuator, and it has been designed to calculate the electrostatic force F1
as electrical current output as a function of drive voltage(s).
Module II: For the viscoelastic suspension to calculate the restoring force
F2 as current output.
Module III: which has been inserted between the viscoelastic suspension
and the electrostatic actuator, is the EOM cosolver to calculate the
velocity and the displacement x as a function of the electrostatic and
restoring forces.
Module IV: the mechanical anchor
Those sub-circuit symbols I–IV have been designed to visually represent
the elements.

11. Verilog-A expressions: We are using Verilog-A, which is an
HDL that can handle various mathematical
operations, including derivation and integration as well
as logical expressions such as an if–then–else clause. It
also has versatility of defining the input and output ports
in either the electrical current and voltage modes.
Verilog-A description can be placed in a more
straightforward manner by using mathematical
expressions

12. Electrostatic Actuator module:
HDL equivalent circuit description for electrostatic parallel-plate
actuator

13. Block1: defines the initial conditions
for the displacement
Block 2:the acceleration a is
calculated from the net electrostatic
attractive force and the restoring
force, divided by the lumped mass m.
Block 3: where a logical flag vi0integ
is set to be one when the
displacement x1 comes into contact
with the mechanical stoppers at limit
or limit on the positive and negative
directions, respectively. When vi0integ
is fulfilled to be one, the velocity is
forced to be null by the conditional
description in the idt function, and
accordingly, displacement x1 remains
at the stopper position.
In a similar manner, the displacement
is obtained by integrating the velocity;
the value of v1 is read as voltage, as
described in block.

14. Block 4: To avoid accumulative error in calculating the displacement
Block 5: Finally, in block
Block 6: the resultant displacement x1 is exported to the output ports
HDL equivalent circuit description for viscoelastic
suspension

15. Transient analysis result of
electrostatic parallel-plate actuator;
dis- placement as a function of
applied voltage.
Dashed Line: Triangular drive Voltage
Solid line: displacement of movable
plate
AC harmonic analysis result of
electrostatic parallel-plate
actuator; input reactance spectrum

16. Automatically synthesized mask layout for the electrostatic
silicon resonator. Dimensional parameters are used in the
corresponding PCell script code.
Part of PCell script codes to automatically
generate layout patterns for the viscoelastic
suspension module
COMSOL simulation results of modal analysis

17. Comparison of MEMS Equivalent circuit modeling
MEMS Simulation Platform

18. Simulation and experimental results
of the actual electrostatic parallelplate actuator.
(a) Capacitance-versus-drive-voltage
curve.
(b) Capacitance-versus-frequency
characteristics

19. Conclusion
We have studied a
novel multiphysics simulation and design
technique for CMOS-MEMS based on an electrical circuit simulator
with a Verilog-A-compatible HDL in the Cadence Virtuoso
environment.
The EOM for mechanical behavior can be implemented as an
equivalent circuit in an analog-computation style such that
electromechanical motion can be cosolved with electrical circuitry
on a single platform without transferring FEM-generated data set
between different simulation tools.
An electrostatic MEMS resonator can be modeled within the
developed simulation platform to show the multiphysics handling
capability for the microelectromechanical behavior and the
electrical transistor circuit.

20. *
Any Query