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Optimal design of a CMOS opamp via geometric programming
 IEEE Transactions on ComputerAided Design
, 2001
"... We describe a new method for determining component values and transistor dimensions for CMOS operational ampli ers (opamps). We observe that a wide variety of design objectives and constraints have a special form, i.e., they are posynomial functions of the design variables. As a result the ampli er ..."
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Cited by 51 (10 self)
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We describe a new method for determining component values and transistor dimensions for CMOS operational ampli ers (opamps). We observe that a wide variety of design objectives and constraints have a special form, i.e., they are posynomial functions of the design variables. As a result the ampli er design problem can be expressed as a special form of optimization problem called geometric programming, for which very e cient global optimization methods have been developed. As a consequence we can e ciently determine globally optimal ampli er designs, or globally optimal tradeo s among competing performance measures such aspower, openloop gain, and bandwidth. Our method therefore yields completely automated synthesis of (globally) optimal CMOS ampli ers, directly from speci cations. In this paper we apply this method to a speci c, widely used operational ampli er architecture, showing in detail how to formulate the design problem as a geometric program. We compute globally optimal tradeo curves relating performance measures such as power dissipation, unitygain bandwidth, and openloop gain. We show how the method can be used to synthesize robust designs, i.e., designs guaranteed to meet the speci cations for a
MAELSTROM: Efficient simulationbased synthesis for custom analog cells
 Proc. of the 1999 ACM/IEEE Design Automation Conference
, 1999
"... Analog synthesis tools have failed to migrate into mainstream use primarily because of difficulties in reconciling the simplified models required for synthesis with the industrialstrength simulation environments required for validation. MAELSTROM is a new approach that synthesizes a circuit using t ..."
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Cited by 27 (6 self)
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Analog synthesis tools have failed to migrate into mainstream use primarily because of difficulties in reconciling the simplified models required for synthesis with the industrialstrength simulation environments required for validation. MAELSTROM is a new approach that synthesizes a circuit using the same simulation environment created to validate the circuit. We introduce a novel genetic/ annealing optimizer, and leverage network parallelism to achieve efficient simulatorintheloop analog synthesis. ___________________________ Permission to make digital/hardcopy of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage, the copyright notice, the title of the publication and its date appear, and notice is given that copying is by permission of ACM, Inc. To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee.
Fuzzy Finitestate Automata Can Be Deterministically Encoded into Recurrent Neural Networks
, 1996
"... There has been an increased interest in combining fuzzy systems with neural networks because fuzzy neural systems merge the advantages of both paradigms. On the one hand, parameters in fuzzy systems have clear physical meanings and rulebased and linguistic information can be incorporated into adapt ..."
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Cited by 13 (5 self)
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There has been an increased interest in combining fuzzy systems with neural networks because fuzzy neural systems merge the advantages of both paradigms. On the one hand, parameters in fuzzy systems have clear physical meanings and rulebased and linguistic information can be incorporated into adaptive fuzzy systems in a systematic way. On the other hand, there exist powerful algorithms for training various neural network models. However, most of the proposed combined architectures are only able to process static inputoutput relationships, i.e. they are not able to process temporal input sequences of arbitrary length. Fuzzy finitestate automata (FFAs) can model dynamical processes whose current state depends on the current input and previous states. Unlike in the case of deterministic finitestate automata (DFAs), FFAs are not in one particular state, rather each state is occupied to some degree defined by a membership function. Based on previous work on encoding DFAs in discretetim...
ASF: A practical simulationbased methodology for the synthesis of custom analog circuits
 IEEE/ACM Int. Conf. on Computer Aided Design
, 2001
"... Abstract: This paper describes ASF, a novel celllevel analog synthesis framework that can size and bias a given circuit topology subject to a set of performance objectives and a manufacturing process. To manage complexity and timetomarket, SoC designs require a high level of automation and reuse. ..."
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Cited by 9 (1 self)
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Abstract: This paper describes ASF, a novel celllevel analog synthesis framework that can size and bias a given circuit topology subject to a set of performance objectives and a manufacturing process. To manage complexity and timetomarket, SoC designs require a high level of automation and reuse. Digital methodologies are inapplicable to analog IP, which relies on tight control of lowlevel device and circuit properties that vary widely across manufacturing processes. This analog synthesis solution automates these tedious, technology specific aspects of analog design. Unlike previously proposed approaches, ASF extends the prevalent “schematic and SPICE ” methodology used to design analog and mixedsignal circuits. ASF is topology and technology independent and can be easily integrated into a commercial schematic capture design environment. Furthermore, ASF employs a novel numerical optimization formulation that incorporates classical downhill techniques into stochastic search. ASF consistently produces results comparable to expert manual design with 10x fewer candidate solution evaluations than previously published approaches that rely on traditional stochastic optimization methods. I.
Thornber, Equivalence in knowledge representation: automata, recurrent neural networks, and dynamical fuzzy systems
 in: Proceedings of the IEEE
, 1999
"... Neurofuzzy systems—the combination of artificial neural networks with fuzzy logic—have become useful in many application domains. However, conventional neurofuzzy models usually need enhanced representational power for applications that require context and state (e.g., speech, time series prediction ..."
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Cited by 4 (1 self)
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Neurofuzzy systems—the combination of artificial neural networks with fuzzy logic—have become useful in many application domains. However, conventional neurofuzzy models usually need enhanced representational power for applications that require context and state (e.g., speech, time series prediction, control). Some of these applications can be readily modeled as finite state automata. Previously, it was proved that deterministic finite state automata (DFA) can be synthesized by or mapped into recurrent neural networks by directly programming the DFA structure into the weights of the neural network. Based on those results, a synthesis method is proposed for mapping fuzzy finite state automata (FFA) into recurrent neural networks. Furthermore, this mapping is suitable for direct implementation in very large scale integration (VLSI), i.e., the encoding of FFA as a generalization of the encoding of DFA in VLSI systems. The synthesis method requires FFA to undergo a transformation prior to being mapped into recurrent networks. The neurons are provided with an enriched functionality in order to accommodate a fuzzy representation of FFA states. This enriched neuron functionality also permits fuzzy parameters of FFA to be directly represented as parameters of the neural network. We also prove the stability of fuzzy finite state dynamics of the constructed neural networks for finite values of network weight and, through simulations, give empirical validation of the proofs. Hence, we prove various knowledge equivalence representations between neural and fuzzy systems and models of automata.
Equivalence in Knowledge Representation: Automata, Recurrent Neural Networks, and Dynamical Fuzzy Systems
 PROCEEDINGS OF THE IEEE
, 1999
"... Neurofuzzy systemsthe combination of artificial neural networks with fuzzy logichave become useful in many application domains. However, conventional neurofuzzy models usually need enhanced representation power for applications that require context and state (e.g., speech, time series prediction, ..."
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Cited by 1 (1 self)
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Neurofuzzy systemsthe combination of artificial neural networks with fuzzy logichave become useful in many application domains. However, conventional neurofuzzy models usually need enhanced representation power for applications that require context and state (e.g., speech, time series prediction, control). Some of these applications can be readily modeled as finite state automata. Previously, it was proved that deterministic finite state automata (DFA) can be synthesized by or mapped into recurrent neural networks by directly programming the DFA structure into the weights of the neural network. Based on those results, a synthesis method is proposed for mapping fuzzy finite state automata (FFA) into recurrent neural networks. Furthermore, this mapping is suitable for direct implementation in very large scale integration (VLSI), i.e., the encoding of FFA as a generalization of the encoding of DFA in VLSI systems. The synthesis method requires FFA to undergo a transformation prior to being mapped into recurrent networks. The neurons are provided with an enriched functionality in order to accommodate a fuzzy representation of FFA states. This enriched neuron functionality also permits fuzzy parameters of FFA to be directly represented as parameters of the neural network. We also prove the stability of fuzzy finite state dynamics of the constructed neural networks for finite values of network weight and, through simulations, give empirical validation of the proofs. Hence, we prove various knowledge equivalence representations between neural and fuzzy systems and models of automata.
PROTOTYPE IMPLEMENTATION OF A WWW BASED ANALOG CIRCUIT DESIGN TOOL
"... A new CAD tool used for the interactive exploration of a design space has been developed. The interactive nature of the tool facilitates the acquisition of designer knowledge which may accelerate the development of improved circuit topologies in the future. The tool's crossplatform compatibility an ..."
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A new CAD tool used for the interactive exploration of a design space has been developed. The interactive nature of the tool facilitates the acquisition of designer knowledge which may accelerate the development of improved circuit topologies in the future. The tool's crossplatform compatibility and network centric architecture prevents reinvention and facilitates organizationwide or worldwide communication via design knowledge repositories. To demonstrate its utility in the area of analog circuit design, the tool was used to model the design tradeoffs available during the design of a telescopic cascode amplifier. There was good agreement between the response predicted by the new tool and a full SPICE simulation. 1.
Recurrent Neural Networks Learn Deterministic Representations of Fuzzy FiniteState Automata
, 1998
"... The paradigm of deterministic finitestate automata (DFAs) and their corresponding regular languages have been shown to be very useful for addressing fundamental issues in recurrent neural networks. The issues that have been addressed include knowledge representation, extraction, and refinement as w ..."
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The paradigm of deterministic finitestate automata (DFAs) and their corresponding regular languages have been shown to be very useful for addressing fundamental issues in recurrent neural networks. The issues that have been addressed include knowledge representation, extraction, and refinement as well development of advanced learning algorithms. Recurrent neural networks are also very promising tool for modeling discrete dynamical systems through learning, particularly when partial prior knowledge is available. The drawback of the DFA paradigm is that it is inappropriate for modeling vague or uncertain dynamics; however, many realworld applications deal with vague or uncertain information. One way to model vague information in a dynamical system is to allow for vague state transitions, i.e. the system may be in several states at the same time with varying degree of certainty; fuzzy finitestate automata (FFAs) are a formal equivalent of such systems. It is therefore of interest to study how uncertainty in the form of FFAs can be modeled by deterministic recurrent neural networks. We have previously proven that secondorder recurrent neural networks are able to represent FFAs, i.e. recurrent networks can be constructed that assign fuzzy memberships to input strings with arbitrary accuracy. In such networks, the classification performance is independent of the string length. In this paper, we are concerned with recurrent neural networks that have been trained to behave like FFAs.In particular, we are interested in the internal representation of fuzzy states and state transitions and in the extraction of knowledge in symbolic form.