Showing papers by "Lars Hedrich published in 2015"

FEATS: Framework for Explorative Analog Topology Synthesis

Abstract: This paper proposes a new methodology for automated analog circuit synthesis, aiming to address the challenges known from other analog synthesis approaches: unsatisfactory time predictability due to stochastic-driven circuit generation methods, the dereliction of the creative part during the design process, and the inflexibility leading to synthesis tools, which mostly only handle just one circuit class. This contribution presents the underlying concepts and ideas to provide the predictability, flexibility, and creative freedom in order to elevate analog circuit design to the next step. A circuit generation algorithm is presented, which allows a full design-space exploration. Furthermore, an isomorphism algorithm is developed, which reduces a given set of circuits to its unique being one of the first methodologies addressing this issue. Thus, the algorithm handles vast amounts of circuits in a very efficient manner. The results demonstrate the claimed feasibility and applicability of the synthesis framework in general and in the context of system design.

Ageing simulation of analogue circuits and systems using adaptive transient evaluation

Abstract: Simulating ageing effects in analogue circuits requires both ageing models and a circuit simulator which is capable of a stress dependent, ageing and recovery aware model evaluation during long term transient simulation. Common approaches on reliability simulation often involve aged models, age precomputation, or lookup tables instead of integrated ageing simulation using memory aware ageing models. Long term transient ageing simulation enhances reliability simulation. This paper presents a framework to model and simulate ageing effects using an adaptive two-times evaluation scheme. This integrates full ageing effect models into behavioural device models. In addition, we introduce semantics for modelling stress levels and ageing parameters in hardware description languages. Our approach is a fully integrated simulation solution, enabling correct and efficient simulation of ageing systems over their lifetimes. We demonstrate how transistor level ageing effects critically affect the operation of a circuit. Our examples incorporate ageing monitors, redundant parts, and self-repair functionality into analogue systems.

Method for system level vibro-acoustic gear modeling and simulation of electro-mechanical drive trains

Abstract: A generic simulation method within heterogeneous system modeling is proposed enabling multi-domain vibro-acoustic gear simulation of electro-mechanical drive trains. The modeling approach accounts for cross-domain system simulation and numerical vibro-acoustic analysis including vibration excitation, structure-borne noise transmission and airborne sound emission. Peripheral mechanisms allow conservative coupling between different physical domains e.g. mechanical, electrical and thermal domain using a generalized physical network. The simulation method fulfills typical system model requirements - modularity, reusability, extensibility, simplicity and efficiency - by choosing a specific simulation technique for each system part. With regard towards the vibro-acoustic analysis, efficient lumped parameter modeling of gear mesh, multi-body simulation of gear components and bidirectional coupling between modal modes of gear housing geometries and rigid-body motion, ensure rapid prototyping. For method verification a system level vibro-acoustic gear model of an electro-mechanical drive train is generated. The simulation model allows studying rotational oscillations of the output shaft as well as three-dimensional multi-body vibration of gear parts and peripheral components. Though no partial differential equations are solved during the system simulation, spatial distribution of housing deflection can be analyzed. Subsequently, experimental results of motor torque and motor speed as well as surface vibration measured by means of a laser vibrometer are used for model validation. It is shown that the proposed method enables the analysis of airborne sound emission within system simulation. Finally, limitations of the modeling approach are illustrated.

Semiautomatic implementation of a bioinspired reliable analog task distribution architecture for multiple analog cores

Abstract: In this paper we present a silicon implementation of a bioinspired analog task distribution system for enabling reliable analog multi-core systems. The increase in reliability is achieved by a dependable task distribution architecture using a hormone based mechanism. The specifications are generated by a feasibility analysis of the algebraic description of the architecture. Starting from the specifications, an automated analog synthesis framework is used to fasten the time-consuming design of the needed analog amplifiers. The complete system with the designed amplifiers has been layouted and fabricated. We present measurements of two different architectures of task distribution system on silicon showing the full functionality of the system and the design methodology.