Chenxu Zhao

An efficient and accurate MEMS accelerometer model with sense finger dynamics for applications in mixed-technology control loops

This contribution presents a novel MEMS accelerometer model implemented in VHDL-AMS. The model includes sense finger dynamics, which allow accurate performance prediction of a MEMS accelerometer in a mixed-technology control loop. A distributed mechanical sensing element model is developed and the effect of the sense finger dynamics is analyzed. The sense finger dynamics might cause a failure of the Sigma-Delta control loop which is captured by the proposed model but cannot be correctly modeled using the conventional approach.

An Extension to VHDL-AMS for AMS Systems with Partial Differential Equations

This paper proposes VHDL-AMS syntax extensions that enable descriptions of AMS systems with partial differential equations. We named the extended language VHDL-AMSP. An important specific need for such extensions arises from the well known MEMS modelling difficulties where complex digital and analogue electronics interfaces with distributed mechanical systems. The new syntax allows descriptions of new VHDL-AMS objects, such as partial quantities, spatial coordinates and boundary conditions. Pending the development of a new standard, a suitable pre-processor has been developed to convert VHDL-AMSP into the existing VHDL-AMS 1076.1 standard automatically. The pre-processor allows development of models with partial differential equations using currently available simulators. As an example, a VHDL-AMSP description for the sensing element of a MEMS accelerometer is presented, converted to VHDL-AMS 1076.1 and simulated in SystemVision.

Genetic-based automated synthesis and optimization of MEMS accelerometers with sigma-delta control

This contribution presents a novel methodology for automated optimal layout synthesis of MEMS systems embedded in electronic control circuitry from user defined high-level performance specifications and design constraints. The proposed approach is based on simulation-based optimization where automated configuration selection for electronic blocks and synthesis of mechanical layouts are coupled with calculations of optimal design parameters. The underlying dedicated MEMS simulator supports distributed mechanical dynamics to enable accurate performance prediction of critical mechanical components, such as acceleration sensing elements which form an essential part of the mixed-technology control loop.

An automated design flow for MEMS accelerometers with Sigma-Delta control

This contribution presents a novel methodology for automated optimal design of MEMS accelerometers embedded in electronic control circuitry from user defined high-level performance specifications and design constraints. The proposed approach is based on simulation-based optimisation where automated configuration selection for electronic blocks and synthesis of mechanical layouts are coupled with calculations of optimal design parameters. The underlying dedicated MEMS simulator supports distributed mechanical dynamics to enable accurate performance prediction of critical mechanical components, such as acceleration sensing elements which form an essential part of the mixed-technology control loop.

Automated Performance Optimisation and Layout Synthesis of MEMS Accelerometer with Sigma-Delta Force-Feedback Control Loop

This contribution presents a novel methodology for automated optimal design of a MEMS accelerometer with Sigma-Delta force-feedback control loop from user defined high-level performance specifications and design constraints. The proposed approach is based on a simulation-based optimization technology using a genetic algorithm. The layout of the mechanical sensing element is generated simultaneously with the optimal design parameters of the Sigma-Delta control loop. As currently available implementations of AMS HDL languages are not suitable for complex mixed-technology system optimisation, the algorithm as well as aa fast dedicated sigma-delta accelerometer simulator have been implemented in C++. The underlying accelerometer model includes the sense finger dynamics described by a partial differential equation, which enables accurate performance prediction of the sensing element embedded in a in mixed-technology control loop.

An extension to SystemC-A to support mixed-technology systems with distributed components

This contribution proposes syntax extensions to SystemC-A that support mixed-technology system modelling where components might exhibit distributed behaviour modelled by partial differential equations. The important need for such extensions arises from the well known modelling difficulties in hardware description languages where complex electronics in a mixed-technology system interfaces with distributed components from different physical domains, e.g. mechanical, magnetic or thermal. A digital MEMS accelerometer with distributed mechanical sensing element is used as a case study to illustrate modelling capabilities offered by the proposed extended syntax of SystemC-A.