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47
Retinomorphic Vision Systems
 IEEE Micro
, 1996
"... The new generation of silicon retinae has two defining characteristics. First, these synthetic retinae are morphologically equivalent to their biological counterpartsat an appropriate level of abstraction. Second, they accomplish all four major operations performed by biological retinae using neu ..."
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Cited by 41 (10 self)
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The new generation of silicon retinae has two defining characteristics. First, these synthetic retinae are morphologically equivalent to their biological counterpartsat an appropriate level of abstraction. Second, they accomplish all four major operations performed by biological retinae using neurobiological principles: (1) continuous sensing for detection, (2) local automatic gain control for amplification, (3) spatiotemporal bandpass filtering for preprocessing, and (4) adaptive sampling for quantization. I introduce the term retinomorphic to refer to this subclass of the neuromorphic electronic systems [30]. I compare and contrast their design principles with the standard practice in imager design. I argue that neurobiological principles are best suited to perceptive systems [43] that go beyond reproducing the dynamic scene, like a conventional video camera does, to extracting salient information in real time [3]. I shall present results from a fully operational retinomorphic vis...
Translinear Circuits Using Subthreshold FloatingGate MOS Transistors
 Analog Integrated Circuits and Signal Processing
, 1996
"... . We describe a family of currentmode circuits with multiple inputs and multiple outputs whose output currents are products and/or quotients of powers of the input currents. These circuits are made up of multipleinput floatinggate MOS (FGMOS) transistors operating in the subthreshold regime. The ..."
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Cited by 38 (9 self)
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. We describe a family of currentmode circuits with multiple inputs and multiple outputs whose output currents are products and/or quotients of powers of the input currents. These circuits are made up of multipleinput floatinggate MOS (FGMOS) transistors operating in the subthreshold regime. The powers are set by capacitor ratios; hence, they can be quite accurate. We analyze the general family of such circuits and present experimental data from several members that we fabricated in a standard 2¯m doublepoly pwell process through MOSIS. 1. Introduction Information processing using analog VLSI systems has recently become the subject of much interest and active research [1], [2]. In particular, the currentmode approach is the focus of much attention [3]. In this paradigm, the quantities of interest are represented by currents, whereas the circuit voltages are thought of as playing only an incidental role. Among the vast array of nonlinear operations required to perform currentmod...
Analog VLSI signal processing: why, where, and how
 Analog Integrated Circuits and Signal Processing 6
, 1994
"... Analog VLSI signal processing is most effective when precision is not required, and is therefore an ideal solution for the implementation of perception systems. The possibility to choose the physical variable that represents each signal allows all the features of the transistor to be exploited oppor ..."
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Cited by 36 (1 self)
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Analog VLSI signal processing is most effective when precision is not required, and is therefore an ideal solution for the implementation of perception systems. The possibility to choose the physical variable that represents each signal allows all the features of the transistor to be exploited opportunistically to implement very dense time and amplitudecontinuous processing cells. This paper describes a simple model that captures all the essential features of the transistor. This symmetrical model also supports the concept of pseudoconductance which facilitates the implementation f linear networks of transistors. Basic combinations of transistors in the current mirror, the differential pair and the translinear loop are revisited as support material for the description of a variety of building blocks. These examples illustrate the rich catalogue of linear and nonlinear operators that are available for local and collective analog processing. The difficult problem of analog storage is addressed briefly, as well as various means for implementing the necessary intrachip and interchip communication.
CMOS LowPower Analog Circuit Design
"... This chapter covers device and circuit aspects of lowpower analog CMOS circuit design. The fundamental limits constraining the design of lowpower circuits are first recalled with an emphasis on the implications of supply voltage reduction. Biasing MOS transistors at very low current provides new f ..."
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Cited by 19 (0 self)
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This chapter covers device and circuit aspects of lowpower analog CMOS circuit design. The fundamental limits constraining the design of lowpower circuits are first recalled with an emphasis on the implications of supply voltage reduction. Biasing MOS transistors at very low current provides new features but requires dedicated models valid in all regions of operation including weak, moderate and strong inversion. Lowcurrent biasing also has a strong influence on noise and matching properties. All these issues are discussed, together with the particular aspects related to passive devices and parasitic effects. The design process has to be supported by efficient and accurate circuit simulation. To this end, the EKV compact MOST model for circuit simulation is shortly presented. The use of the basic concepts such as pinchoff voltage, inversion factor and specific current are highlighted thanks to some very simple but fundamental circuits and to an effective use of the model. New design techniques that are appropriate for lowpower and/or lowvoltage circuits are presented with an emphasis on the analog floating point technique, the instantaneous companding principle, and their application to filters.
The MultipleInput Translinear Element: A Versatile Circuit Element
 PROCEEDINGS OF THE 1998 IEEE ISCAS
, 1998
"... We define the multipleinput translinear element (MITE), a versatile circuit primitive from which we can construct lowvoltage translinear circuits and logdomain filters. A Kinput MITE produces an output current that is exponential in a weighted sum of its K input voltages. We briefly discuss s ..."
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Cited by 12 (5 self)
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We define the multipleinput translinear element (MITE), a versatile circuit primitive from which we can construct lowvoltage translinear circuits and logdomain filters. A Kinput MITE produces an output current that is exponential in a weighted sum of its K input voltages. We briefly discuss six MITE implementations and show experimental data from two of these six that we have fabricated in a 2µm doublepoly CMOS process available through MOSIS.
A General Translinear Principle for Subthreshold MOS Transistors
 IEEE Transactions on Circuits and Systems
, 1999
"... This paper revises the conditions under which the translinear principle can be fully exploited for MOS transistors operating in subthreshold. Due to the exponential nature of subthreshold MOS transistors, the translinear principle applies immediately as long as the sourcetobulk voltages are made e ..."
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Cited by 9 (0 self)
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This paper revises the conditions under which the translinear principle can be fully exploited for MOS transistors operating in subthreshold. Due to the exponential nature of subthreshold MOS transistors, the translinear principle applies immediately as long as the sourcetobulk voltages are made equal to zero (or constant). This paper addresses the conditions under which subthreshold MOS transistors still satisfy a translinear principle, but without imposing this constraint on all VBS voltages. It is found that the translinear principle results in a more general formulation than the originally found for BJT's since now multiple translinear loops can be involved. The constraint of an even number of transistors is no longer necessary. Some corollaries are stated as well and, finally, it is shown how to use the theorem for subthreshold MOS transistors operated in the ohmic regime. Index TermsCMOS analog integrated circuits, current mode circuits, lowpower circuits, nonlinear circui...
An onoff logdomain circuit that recreates adaptive filtering in the retina
 IEEE Trans. Circuits Syst. I, Reg. Papers
, 2005
"... Abstract—We introduce a new approach to synthesizing Class AB logdomain filters that satisfy dynamic differentialmode and commonmode constraints simultaneously. Whereas the dynamic differentialmode constraint imposes the desired filtering behavior, the dynamic commonmode constraint solves the z ..."
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Cited by 8 (7 self)
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Abstract—We introduce a new approach to synthesizing Class AB logdomain filters that satisfy dynamic differentialmode and commonmode constraints simultaneously. Whereas the dynamic differentialmode constraint imposes the desired filtering behavior, the dynamic commonmode constraint solves the zerodcgain problem, a shortcoming of previous approaches. Also, we introduce a novel push–pull circuit that serves as a currentsplitter; it rectifies a differential signal into the ON and OFF paths in our logdomain filter. As an example, we synthesize a firstorder lowpass filter, and, to demonstrate the rejection of dc signals, we implement an adaptive filter by placing this lowpass circuit in a variablegain negativefeedback path. Feedback gain is controlled by signal energy, which is extracted simply by summing complementary ON and OFF signals—dc signals do not contribute to the signal energy nor are they amplified by the feedback. We implement this adaptive filter design in a silicon chip that draws biological inspiration from visual processing in the mammalian retina. It may also be useful in other applications that require dynamic timeconstant adaptation. Index Terms—Adaptive filtering, artificial vision, class AB circuits, neuromorphic engineering.
An RMSDC converter based on the dynamical translinear principle
 in Proc. ESSCIRC
, 1996
"... Translinear or logdomain #lters are theoretically exact realisations of linear di#erential equations. However, the dynamical translinear principle can also be applied to the implementation of nonlinear di#erential equations. In this paper, an RMSDC converter is proposed, comprising a direct imp ..."
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Cited by 7 (3 self)
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Translinear or logdomain #lters are theoretically exact realisations of linear di#erential equations. However, the dynamical translinear principle can also be applied to the implementation of nonlinear di#erential equations. In this paper, an RMSDC converter is proposed, comprising a direct implementation of the corresponding nonlinear di#erential equation by means of the dynamical translinear principle. Correct operation of the circuit was veri#ed through measurements. 1 Introduction The translinear principle #1# plays a key role in conventional implementations of RMStoDC conversion #2#. A wellknown RMSDC converter is shown in Fig. 1. The squarerdivider basically comprises a fourtransistor, i.e. secondorder #3#, translinear loop. As the squarerdivider facilitates onequadrant operation, its input signal is fullwave recti#ed. It calculates the current I 2 in =I out , where I out is the output current of the RMSDC converter and is equal to the mean value of I 2 in ...