Partner und Internationale Organisationen
(Englisch)
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Siemens Aktiengesellschaft, Munich (D), Siemens Entwicklungszentrum f. Mikroelektronik, Villach (A), University of Hanover, Inst. of Microelectronic Syst. (D)
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Abstract
(Englisch)
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For reducing the cost, size, and weight of hand-held electronic equipment as well as for improving the autonomy of its batteries, the power dissipation of the electronics is of major concern. In particular, modern communications systems require extensive digital signal processing and consequently the supply voltage of the entire system is chosen mainly to optimise the efficiency of the digital gates. Over the years, this led to a steady decrease of the supply voltages of mixed analogue/digital systems, where the analogue building blocks have to follow this trend. This situation complicates the design of analogue circuits considerably, since in many cases it is not sufficient to optimise traditional circuits, but it is required to apply completely new circuit concepts. In particular under such difficult conditions, more reliable methods for design verification are required, for shortening the total product development time.
One of the objectives of this project is the development of fully integrated filters, A/D-converters, and D/A-converters in CMOS and BiCMOS technologies for cordless and mobile telephone applications (according to the DECT and the GSM standard, respectively). For the next generation of these devices, rather traditional filter concepts will be utilised, but they have to be optimised aggressively to be capable of a supply voltage as low as 2.5 V. This is already a difficult task, but for future generations of DECT and GSM phones even lower supply voltages are predicted. Therefore, in parallel to this work, filters are developed which use compressed voltages for internal signal representation, and consequently they allow lower supply voltages without affecting their principal signal processing function. As measurements of test structures demonstrate, these so called 'log-domain filters' allow supply voltages less than 1.2 V.
Besides this circuit design work, there is also a software tool for Formal Verification of analogue circuits developed within the ALPINS project. Traditionally, design verification is based on circuit simulation, where the circuit's response to a representative set of input signals is simulated and assessed. Since the completeness of this input vector can never be proved, the reliability of this method is limited. In contrast to that, the Formal Verification method can evaluate the circuit's behaviour by means of symbolic analysis. Since it does not consider the circuit's response to particular stimuli, the result is a generally valid proof of the correctness of the design.
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