A Mixed-Signal/MEMS CMOS Co-Design Flow with MEMS-IP Publishing / Integration Che-Sheng Chen 1 Louis Thiam 2, Ahmed Hussein Osman 2, Kuei-Ann Wen 1, Long-Sheng Fan 3 1 Inst. Of Electronics, National Chiao Tung University, Taiwan 2 VCAD, Cadence Design System, Ltd, USA 3 Inst. Of NanoEngineering and MicroSystems, National Tsing Hua Unversity, Taiwan

Motivation Analog+Mixed-Signal + Digital Components Signal Proc Clock Tree & Divider C-to-V ADC MEMS IP Glue Logic MEMS Inter-digitized Sensor FEM Simulation Cross-domain Verification Design Team Fragmentation Cross-discipline Verification MEMS + Mixed-Signal + Digital concurrent design Integration Methods for efficient use of EDA + FEM Single monolithic CMOS-MEMS C-to-V Inter-digitized Sensor IP

Outlines MS/MEMS Co-Design Flow Overview MEMS Design Sub-flow  MEMS HDL Behavioral Modeling  DRC-aware Layout Generation MEMS-IP Publishing/Integration Interface (SIMPLI)  Overview  Layout Black-boxing  HDL Code Encryption  Electrical Parasitic Extraction Mixed-Signal Design Sub-flow  Correlated Double Sampling Capacitive Readout Summary

MS/MEMS Co-design Flow IP Integration Approach MEMS design flow is traditionally top- down starting from mechanical characteristics with FEM iterations SIPP-SIMPLI interface is providing the bridge between MEMS and IC designers IC design flow integrate MEMS components as IP

Outlines MS/MEMS Co-Design Flow Overview MEMS Design Sub-flow  MEMS HDL Behavioral Modeling  Specification-Driven Verification  DRC-aware Layout Generation MEMS-IP Publishing/Integration Interface (SIMPLI)  Overview  Database Structure  Code/Layout Encryption  Electrical Parasitic Extraction Mixed-Signal Design Sub-flow  Correlated Double Sampling Capacitive Readout Summary

MEMS Design Sub-flow Top-down approach

MEMS Design Sub-flow Details Interleaved Interaction

MEMS HDL Macro-Modeling (1) Interfacing multi-physics, electrical and MEMS geometries Advantages of HDL behavioral modelling for MEMS:  Multi-disciplinary language combining physics and electrical quantities  Open standard to enable re-use and flexible mixed- signal simulation environment  Ability to create highly parameterizable component libraries  MEMS geometrical structure description can be part of the macro-model  Natural convergence toward mixed-signal and digital verification

MEMS HDL Macro-Modeling (2) Describing multi-physics equivalence with electrical Each physical equations can be stated independently and HDL concurrent process statement enables system solution convergence No limit to describe 2 nd, 3 rd order effects but at expense of development time Models can be further enhanced based on results extracted from FEM simulation

MEMS Functional Verification cockpit Specification-driven verification

MEMS Functional Validation Re-usable and scalable verification environment Single specification- driven environment for:  Re-use and automation of verification tasks  Synthetic view of design status versus specification target  Testing environment can be hierarchical  Use model similar to digital functional verification

MEMS Physical Design DRC aware parameterizable layout generator Finger Width Spring Beams Width Finger Length Eatch Hole Separation Length Eatch Hole Width Length Initial Displacement Electrode-to-Mass Separation Length SKILL based PCell enables parameterization over geometrical parameters with DRC awareness Parameterization linked directly to HDL macro-modelling in order to enabled schematic-driven layout

Outlines MS/MEMS Co-Design Flow Overview MEMS Design Sub-flow  MEMS HDL Behavioral Modeling  Specification-Driven Verification  DRC-aware Layout Generation MEMS-IP Publishing/Integration Interface (SIMPLI)  Overview  Database Structure  Code/Layout Encryption  Electrical Parasitic Extraction Mixed-Signal Design Sub-flow  Correlated Double Sampling Capacitive Readout Summary

SIPP-SIMPLI Subflow concept IP publishing and integration

SIPP-SIMPLI MEMS IP Publishing Subflow Automated approach SIPP-SIMPLI operated on standard inputs and generates views required for Mixed- Signal design within Cadence environment SIPP-SIMPLI requires following Cadence tools:  AMS Incisive for processing HDL models  Abstract Generator for black-box layout generation  Assura for MEMS DRC compliance  QRC for MEMS parasitics extraction

SIPP-SIMPLI MEMS IP Integration Subflow Automated approach Only Virtuoso views have to be re-created in target PDK which might be packaged differently between MEMS IP provider and end-user If PDK package identical between MEMS IP provider and IC designer then MEMS IP published by SIPP-SIMPLI can be re-used as-is

SIPP-SIMPLI Virtuoso Custom Interface Single interface for publishing and integration Single interface and options for both publishing and integration Interface integrated directly with Virtuoso platform and compatible with both IC and IC Support batch processing through SKILL APIs for entire library management and maintenance

SIPP-SIMPLI Layout Processing Layout black-boxing while enabling accurate integration

SIPP-SIMPLI Functional Processing HDL description encrypted while enabling accurate simulation

SIPP-SIMPLI Extraction Processing Layout extraction while enabling accurate parasitics

Outlines MS/MEMS Co-Design Flow Overview MEMS Design Sub-flow  Overview  MEMS HDL Behavioral Modeling  Specification-Driven Verification  DRC-aware Layout Generation MEMS-IP Publishing/Integration Interface (SIMPLI)  Overview  Database Structure  Code/Layout Encryption  Electrical Parasitic Extraction Mixed-Signal Design Sub-flow  Overview  Correlated Double Sampling Capacitive Readout  Design Summary Conclusion

CMOS Mixed-Signal MEMS Subflow concept Meet-in-the-middle approach

CMOS Mixed-Signal MEMS Subflow details Meet-in-the-middle approach

Correlated Double Sampling Readout CDS circuit is suitable for capacitive sensor readout  Offset cancellation & Low frequency noise reduction  Suitable for following Analog to Digital conversion  Following another S/H amplifier for proper sensitivity Process: UMC CMOS-RF 180nm

Schematic Capture of Monolithic Integration

Schematic-Driven Layout Assembly Hierarchical layout while reducing LVS errors Schematic-driven layout enables to track connectivity between schematic and layout view SIPP-SIMPLI creates a connectivity aware view for safe layout integration Custom router could be leveraged since MEMS black-box as connectivity and antenna information SIPP-SIMPLI has also LEF file for digital P&R integration

Design Summary SpecificationsConditionsValueUnit Sensor Input Range±2g Sampling Freq.<100kHz SensitivityVsupply = 3.3v218mv/g SFDRVsupply = 3.3v58.5dB Resonate Freq.6.3kHz Output RMS Noise< 4kHz Vsupply = 3.3v141uV Current ConsumedVsupply = 3.3v Clock Freq. = 100KHz 360uA

[2] Movement of the fingers triggered by external voltage source [1] SEM of the ACC The first result of accelerometer (ACC) fabricated with.18  m 8” CMOS foundry under the constrain of standard CMOS process. [3] Capacitance variation under the excitation of shaker with 20~8kHz shaking. ( The green one is the "PZT reference accelerometer“ provided as the reference and the blue one is the performance of DUT.)

Outlines MS/MEMS Co-Design Flow Overview MEMS Design Sub-flow  Overview  MEMS HDL Behavioral Modeling  Specification-Driven Verification  DRC-aware Layout Generation MEMS-IP Publishing/Integration Interface (SIMPLI)  Overview  Data Structure  Code/Layout Encryption  Electrical Parasitic Extraction Mixed-Signal Design Sub-flow  Overview  Correlated Double Sampling Capacitive Readout  Design Summary Conclusion

A Mixed Signal-MEMS co-design flow is proposed for CMOS/MEMS monolithic integration. A MEMS IP Publishing/Integration interface is developed to enable handshaking between MEMS & Mixed signal circuits. With parametric layout & HDL, MEMS/CMOS co- optimization can be achieved. A fully integrated CMOS monolithic accelerometer has been implemented to demonstrate the proposed design flow.

Q & A