Ralf Sommer

Automated behavioral modeling and analytical model-order reduction by application of symbolic circuit analysis for multi-physical systems

Abstract The aim of symbolic analysis that has its origin in the design of analog circuits is the extraction of dominant system behavior by automated derivation of approximated symbolic formulas. Since exact symbolic analysis will yield exceptionally complex expressions even for rather small systems a class of symbolic approximation techniques have been developed that allow a reduction of the complexity of symbolic equations and their later solution by means of mixed symbolic and numerical strategies. Hence, it becomes possible to reduce the underlying nonlinear differential-algebraic systems of equations (DAE systems) of component-based networks and systems to a behavioral description of a predefined accuracy. It is a major advantage of the approach that the model simplification is performed by an automatic error control and that the simplified model is physically interpretable again. The contribution will give an overview of the symbolic tool Analog Insydes algorithms for extraction of dominant behavior of linear systems, e.g. formulas for poles and zeros as well as algorithms for generating behavioral models from nonlinear DAEs. Moreover, the underlying methodology has been extended to the application of analysis and modeling of gas-pipeline nets and mixed electrical and mechanical systems. For the latter a library was developed in cooperation with the Fraunhofer IIS/EAS for symbolic models of micro-mechanical elements that can be connected to networks, even together with electrical components.

Schematic driven MEMS design

Microelectromechanical systems are important components for so-called cyber-physical systems. If a seamless MEMS design methodology for monolithic and hybrid systems overcomes current tool and workflow discrepancies in MEMS and IC design flows, further capabilities can be made available. This paper gives an overview of requirements on and solution approaches for an integrated MEMS/ASIC design flow.

UVM-based verification of smart-sensor systems

In this contribution, we present a UVM-based methodology for mixed-signal smart-sensor systems. Our approach permits the validation of system functionality before implementation and to verify implementations on various levels of abstraction. The model-based verification approach also helps to build a scalable and re-usable framework, in which assertions and constrained random-stimuli are used to monitor and verify mixed-signal system behavior automatically. Along with the designed UVM -testbench architecture, we describe a novel solution for estimating the power consumption of digital block using application-specific random activity patterns generated during testbench runs.

Systematic MEMS ASIC design flow using the example of an acceleration sensor

With the help of MEMS-ASIC-development methodology the gap between a seamless design of multiphysical systems can be overcome. This contribution gives insight to MEMS2015 results of methodology for synthesis of MEMS. As an example of heterogeneous design an acceleration sensor is presented.

Multi-technology design of an integrated MEMS-based RF oscillator using a novel silicon-ceramic compound substrate

In this paper, an approach towards the realization of a hybrid MEMS-CMOS RF oscillator module using the novel silicon-ceramic (SiCer) compound substrate technology is described. Piezoelectric aluminium-nitride MEMS resonators with quality factors Q up to 2,200 and resonant frequencies of 240, 400 and 600 MHz have been investigated as frequency-selective elements. For RF-compatible hybrid-integrated assembly and packaging, the SiCer compound substrate has been adapted, promising an efficient integration of both, microelectronic and micromechanical devices, on a single carrier substrate. Multiphysical circuit design and simulations using parametrized behavioural MEMS models have been carried out, indicating stable oscillator operation at the design frequency. As one prospective application, such an oscillator module could form part of a compact and power-efficient reconfigurable RF transceiver frontend in SiCer technology, e.g., for mobile communications.

RF-MEMS-platform based on silicon-ceramic-composite-substrates

In the last few years, several Low Temperature Co-fired Ceramics (LTCC) materials with a silicon adapted Coefficient of Thermal Expansion (CTE) have been developed for direct wafer bonding to silicon. BGK (special type designation of Fraunhofer IKTS), a sodium containing LTCC was originally developed for anodic bonding of the sintered LTCC whereas BCT (Bondable Ceramic Tape) tailored for direct silicon bonding of green LTCC tapes to fabricate a quasi-monolithic silicon ceramic compound substrate. This so-called SiCer technique is based on homogeneous nano-structuring of a silicon substrate, a lamination step of BCT and silicon and a subsequent pressure assisted sintering. We present a new approach for an integrated RF-platform-setup combining passive, active and mechanical elements on one SiCer substrate. In this context RF parameters of the silicon adapted LTCC tapes are investigated. We show first technological results of creating cavities at the silicon ceramic interface for SiCer-specific contacting options as well as windows in the ceramic layer of the SiCer substrate for additional silicon processing. A further investigated platform technology is deep reactive ion etching of the silicon-ceramic-composite-substrate. The etching behavior of silicon on BCT will be demonstrated and discussed. With the SiCer technique it is possible to reduce the silicon content at the setup of RF MEMS to a minimum (low signal damping).

A contribution towards model-based design of application-specific MEMS

Abstract The design process of heterogeneous systems containing electro-mechanical components and electronic circuits involves expert knowledge, methods, and tools from different engineering domains. Cost-efficient research and development of such heterogeneous systems requires a systematic design flow without gaps. A contribution towards this global goal is presented in this article. A development and synthesis tool for one-dimensional accelerometer MEMS has been implemented, calculating sensor solutions and generating the models and layouts required for a hierarchical design flow in an automatic, module-based approach. Utilizing this flow, different accelerometers have been designed, manufactured, and characterized. A dedicated readout ASIC was developed to validate their dynamic behaviour.

Frequency compensation of closed-loop feedback amplifier systems

In this paper we consider application-specific frequency compensation of integrated circuit feedback amplifiers through computer-aided analysis and design of closed-loop systems. We employ our symbolic circuit analysis program Analog Insydes to derive transfer functions or poles and zeros of uncompensated amplifiers in closed-loop configuration in analytic form. Then, it will be shown how systematic examination of the resulting symbolic expressions can help to find and evaluate alternative circuit parameter modifications by way of which frequency compensation can be achieved.

Design of a LTE-receiver using a design methodology for multiphysical RF systems

This paper deals with the design of a receiver for LTE band 20 consisting of microelectronic and MEMS-containing function blocks. It shows how multiphysical RF circuits can be considered in one design environment like Cadence Virtuoso. Finally, the simulation tool was extended by suitable models for used MEMS containing design parameters that are important for an electronics engineer. This unifies the design task and facilitates the evaluation of an implementation with and without MEMS by considering the entire receiver chain.

Systematic design strategies for multi-physical RF systems using the example of MEMS oscillator

Latest trends in nearly all domains of daily life require “smart” systems, meaning the combination of sensors and actuators in different physical domains with an intelligent signal processing. As market trends tend to more diversity as well as cheaper and smaller devices, i.e. integrated, heterogeneous systems, shorter design cycles and more flexibility hold the key for the development of such smart sensor/actuator systems. Currently, the design flows for heterogeneous systems are separated. If seamless RF-MEMS design methodology for monolithic and hybrid systems overcomes current methodology and tool discrepancies in electronic and mechanical-design flows, further capabilities can be made available. This paper gives an overview of requirements on and solution approaches for an integrated design flow for RF-MEMS.