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Articles 31 - 42 of 42

Full-Text Articles in Engineering

Synthesis Of Mite Log-Domain Filters With Unique Operating Points, Shyam Subramanian, David Anderson, Paul Hasler, Bradley Minch Jul 2012

Synthesis Of Mite Log-Domain Filters With Unique Operating Points, Shyam Subramanian, David Anderson, Paul Hasler, Bradley Minch

Bradley Minch

Practical log-domain filter circuits might have multiple operating points in regions in which the translinear element does not obey the exponential law. In this paper, a method is proposed to implement any filter by a log-domain circuit that necessarily has a unique operating point. Any state-space description of the filter is shown to have an equivalent description that can be implemented by such a circuit. This methodology is applied to the synthesis of multiple-input translinear element (MITE) filters. As an example, shifted-companion-form (SCF) filters are synthesized. Further, it is proved that the resulting filters have a unique operating point.


A Physical Compact Model Of Dg Mosfet For Mixed-Signal Circuit Applications - Part I: Model Description, Gen Pei, Weiping Ni, Abhishek Kammula, Bradley Minch, Edwin Kan Jul 2012

A Physical Compact Model Of Dg Mosfet For Mixed-Signal Circuit Applications - Part I: Model Description, Gen Pei, Weiping Ni, Abhishek Kammula, Bradley Minch, Edwin Kan

Bradley Minch

To use double-gate (DG) MOSFET for mixed-signal circuit applications, especially for circuits in which the two gates are independently driven, such as in the case of dynamic-threshold and fixed-potential-plane operations, physical compact models that are valid for all modes of operations are necessary for accurate design and analysis. Employing physically rigorous current-voltage (I-V) relationship in subthreshold and above-threshold regions as asymptotic cases, we have constructed a model that joins the two operating regions by using carrier-screening functions. We have included consistently source/drain series resistance, low drain-field mobility, and small-geometry effects of drain-induced barrier lowering (DIBL), MOS interface mobility, velocity saturation …


Low-Voltage Wilson Current Mirrors In Cmos, Bradley Minch Jul 2012

Low-Voltage Wilson Current Mirrors In Cmos, Bradley Minch

Bradley Minch

In this paper, we describe three simple low-voltage CMOS analogs of the Wilson current mirror that function well at all current levels, ranging from weak inversion to strong inversion. Each of these current mirrors can operate on a low power-supply voltage of a diode drop plus two saturation voltages and features a wide output-voltage swing with a cascode-type incremental output impedance. Two of the circuits requires an input voltage of a diode drop plus a saturation voltage while the third one features a low input voltage of a saturation voltage. We present experimental results from versions of these three current …


Charge-Based Chemical Sensors: A Neuromorphic Approach With Chemoreceptive Neuron Mos (Cvmos) Transistors, Nick Shen, Zengtao Liu, Chungho Lee, Bradley Minch, Edwin Kan Jul 2012

Charge-Based Chemical Sensors: A Neuromorphic Approach With Chemoreceptive Neuron Mos (Cvmos) Transistors, Nick Shen, Zengtao Liu, Chungho Lee, Bradley Minch, Edwin Kan

Bradley Minch

A novel chemoreceptive neuron MOS (CνMOS) transistor with an extended floating-gate structure has been designed with several individual features that significantly facilitate system integration of chemical sensing. We have fabricated CνMOS transistors with generic molecular receptive areas and have characterized them with various fluids. We use an insulating polymer layer to provide physical and electrical isolation for sample fluid delivery. Experimental results from these devices have demonstrated both high sensitivity via current differentiation and large dynamic range from threshold voltage shifts in sensing both polar and electrolytic liquids. We have established electrochemical models for both steady-state and transient analyses. Our …


Silicon Synaptic Adaptation Mechanisms For Homeostasis And Contrast Gain Control, Shih-Chii Liu, Bradley Minch Jul 2012

Silicon Synaptic Adaptation Mechanisms For Homeostasis And Contrast Gain Control, Shih-Chii Liu, Bradley Minch

Bradley Minch

We explore homeostasis in a silicon integrate-and-fire neuron. The neuron adapts its firing rate over time periods on the order of seconds or minutes so that it returns to its spontaneous firing rate after a sustained perturbation. Homeostasis is implemented via two schemes. One scheme looks at the presynaptic activity and adapts the synaptic weight depending on the presynaptic spiking rate. The second scheme adapts the synaptic"threshold" depending on the neuron's activity. The threshold is lowered if the neuron's activity decreases over a long time and is increased for prolonged increase in postsynaptic activity. The presynaptic adaptation mechanism models the …


Low Voltage And Performance Tunable Cmos Circuit Design Using Independently Driven Double Gate Mosfets, Arvind Kumar, Bradley Minch, Sandip Tiwari Jul 2012

Low Voltage And Performance Tunable Cmos Circuit Design Using Independently Driven Double Gate Mosfets, Arvind Kumar, Bradley Minch, Sandip Tiwari

Bradley Minch

Independently driven double-gate MOSFETs (DGFETs) facilitate design of analog circuits under digital logic constraints and provide in-circuit parameter adaptability through threshold voltage control. Threshold voltagetuning is achieved by biasing one of the two gates where as strong coupling of surface potentials at the two interfaces provides a low resistance feedback path. The geometry also allows a back-floating gate NVRAM structure with superior scalability and floating gate related analog applications without any read disturbance. This paper gives examples across breadth of circuits where this tunability is exploited.


Floating-Gate Techniques For Assessing Mismatch, Bradley Minch Jul 2012

Floating-Gate Techniques For Assessing Mismatch, Bradley Minch

Bradley Minch

I discuss the importance of capacitor matching in the context of using charge stored on floating-gate MOS (FGMOS) transistors to compensate for transistor mismatch in analog circuits. I describe a simple technique that only involves static measurements for assessing the relative mismatch between capacitors. I also show experimental measurements of capacitor mismatch for small capacitors fabricated in 1.2-μm and 0.35-μm double-poly it n-well CMOS process that are commonly available.


A Simple Class-Ab Transconductor In Cmos, Bradley Minch Jul 2012

A Simple Class-Ab Transconductor In Cmos, Bradley Minch

Bradley Minch

In this paper, we present a simple class-AB CMOS transconductor, which is based on Delbriick's bump/antibump circuit, whose differential output current is an expansive nonlinear function of its differential-mode input voltage. We describe the operation of the new transconductor qualitatively and derive an analytical model of its output currents from the Enz-Krummenacher-Vittoz (EKV) model of the MOS transistor. We also provide experimental measurements of the DC transfer characteristics of a version of the circuit that was fabricated in a 0.5-mumCMOS process through MOSIS.


Evolution Of A Folded Floating-Gate Differential Pair, Bradley Minch Jul 2012

Evolution Of A Folded Floating-Gate Differential Pair, Bradley Minch

Bradley Minch

The author presents a folded floating-gate MOS (FGMOS) differential pair circuit that is capable of simultaneously providing a rail-to-rail common-mode input voltage range and a rail-to-rail output voltage swing with a low power-supply voltage. In this configuration, the voltage drop across the bias current source is folded up into the same range over which the output voltages swing, facilitating low-voltage operation. The floating-gate charge can be used to trim out the offset voltage of the differential pair and to reduce the required power-supply voltage for a given bias current level. The author provides both a qualitative description of how the …


A Programmable Floating-Gate Bump Circuit With Variable Width, Sheng-Yu Peng, Bradley Minch, Paul Hasler Jul 2012

A Programmable Floating-Gate Bump Circuit With Variable Width, Sheng-Yu Peng, Bradley Minch, Paul Hasler

Bradley Minch

We propose a new programmable bump circuit using floating-gate transistors with a simple topology. The center and the width of this bump circuit are orthogonally tunable and programmable. The input signal range is rail to rail and the power consumption does not change dramatically while varying the width. Therefore, this circuit is suitable for low power applications. We use a vector-quantizer as an example to illustrate how this circuit fits into a large scale network.


Construction And Transformation Of Multiple-Input Translinear Element Networks, Bradley Minch Jul 2012

Construction And Transformation Of Multiple-Input Translinear Element Networks, Bradley Minch

Bradley Minch

We present a simple algorithmic procedure for constructing a multiple-input translinear element (MITE) network from a translinear-loop equation. We also give a number of MITE-network transformations that alter the structure of the MITE network without altering the translinear-loop equation that it embodies. The results that we establish in this paper serve as foundations for the synthesis of both static and dynamic MITE networks from high-level specifications.


Implementing The Lorenz Oscillator With Translinear Elements, Kofi Odame, Bradley Minch Mar 2012

Implementing The Lorenz Oscillator With Translinear Elements, Kofi Odame, Bradley Minch

Bradley Minch

Nonlinear processing is often more suitable than the traditional linear approach is for analyzing biological signals. Unfortunately, digital nonlinear operations are computationaly expensive. In contrast, a large variety of nonlinear operations can efficiently be implemented in analog electronics, operating at real-time speeds. The low level of accuracy generally associated with analog processing is not a concern in this scenario, as biological signals themselves typically have low signal-to-noise ratios. One challenge of analog processing is in its apparently- ad hoc design, and the fact that there is very little wide-spread knowledge of systematically implementing analog electronics to perform arbitrary nonlinear computations. …