J.P.A. van der Wagt

Rockwell Automation (United States)

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Alan Seabaugh

University of Notre Dame

Edward Beam

Qorvo (United States)

T.P.E. Broekaert

Aptiv (United States)

Gary Frazier

The University of Texas at Dallas

Frank Morris

Citadel

B. Brar

Johns Hopkins Medicine

T. S. Moise

Texas Instruments (United States)

James S. Harris

Kennesaw State University

James S. Harris

New York University

Timothy B. Boykin

University of Alabama in Huntsville

Cooperative Institutions

Texas Instruments (United States)

Stanford University

University of Alabama in Huntsville

RTX (United States)

Naval Information Warfare Center Pacific

Rockwell Automation (United States)

The University of Texas at Dallas

Applied Research Laboratory at the University of Hawai‘i

University of Maryland, College Park

Georgia Institute of Technology

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Tunneling-based SRAM

Proceedings of the IEEE (1999)

J.P.A. van der Wagt

This paper describes a new high-density low-power circuit approach for implementing static random access memory (SRAM) using low current density resonant tunneling diodes (RTDs). After an overview of semiconductor random access memory architecture and technology, the concept of tunneling-based SRAM (TSRAM) is introduced. Experimental results for a compound semiconductor 1-bit 50-nW TSRAM gain cell using low current density (/spl sim/1 A/cm/sup 2/) RTDs and low-leakage heterostructure field effect transistors are presented. We describe a one-transistor TSRAM cell which could convert silicon dynamic RAM (DRAM) to ultradense SRAM if an ultralow current density (/spl sim/1 /spl mu/A/cm/sup 2/) silicon bistable device is developed. Finally, we present experimental and simulation results for a TSRAM cell using multipeaked I-V curve devices and a multivalued word line. This approach aims at increasing storage density through vertical integration of bistable devices such as RTD's.

Bistability

Dram

Dynamic random-access memory

Memory cell

10.1109/5.752516

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Citations (130)

Observation of resonant tunneling through localized continuum states in electron wave interference diodes

Applied Physics Letters (1994)

R. E. Carnahan M. A. Maldonado K. P. Martin R. J. Higgins J.P.A. van der Wagt

A 13 layer aperiodic semiconductor superlattice electron wave interference filter, designed with thin-film optical interference filter techniques by using the analogies between electromagnetic wave propagation in dielectrics and ballistic electron wave propagation in semiconductors, was realized in the GaAs/AlGaAs material system. Current-voltage measurements at 300 and 77 K show negative differential resistance peaks (with peak-to-valley current ratios of 1.25 and 3.9, respectively) that represent observation of tunneling through an above barrier localized quasibound state. We show that electron wave interference devices could compete with resonant tunneling diodes as high frequency oscillators based on dc device characteristics and theoretical subpicosecond tunneling traversal times.

Tunnel diode

10.1063/1.111604

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Citations (1)

Multibit resonant tunneling diode SRAM cell based on slew-rate addressing

IEEE Transactions on Electron Devices (1999)

J.P.A. van der Wagt Hao Tang T.P.E. Broekaert Alan Seabaugh Yung-Chung Kao

We propose and demonstrate a resonant-tunneling diode (RTD) based memory cell in which N bits are stored in a series combination of N RTDs without internal node contacts. The slew rate of an applied voltage signal determines the circuit switching dynamics and allows addressing of the bits. We verify slew rate dependent switching order of up to four series RTDs experimentally and through SPICE simulation incorporating a physics-based RTD model. The new addressing scheme allows N bits to be stored in a stack of N vertically integrated RTDs compared to log/sub 2/ (N) bits in previous demonstrations. We demonstrate a two-bit two-RTD static memory cell based on the new method.

Slew rate

Spice

Resonant-tunneling diode

10.1109/16.737441

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Citations (26)

Optically clocked track-and-hold for high-speed high-resolution analog-to-digital conversion

E. W. Jacobs J.B. Sobti V.F. Vella R. L. Nguyen D. J. Albares

An optically clocked track-and-hold (TH) circuit for improved TH linearity and noise performance is presented. Results with f/sub in/=1.0073 GHz and sample rate f/sub s/=1.003 GS/s show 11.8 SFDR bits and 9.6 SNR bits.

Spurious-free dynamic range

Linearity

Data conversion

10.1109/mwp.2004.1396871

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Citations (11)

Tight-binding model for GaAs/AlAs resonant-tunneling diodes

Physical review. B, Condensed matter (1991)

Timothy B. Boykin J.P.A. van der Wagt James S. Harris

Models of resonant-tunneling diodes based on the envelope-function approximation often give unsatisfactory results. In order to address some of the shortcomings of these models, we employ a tight-binding model that allows more careful treatment of heterointerfaces than is possible in the envelope-function approach. We use transfer matrices to carry out the calculation and present an improved method that allows us to transfer across larger device dimensions (>1000 \AA{}), thereby permitting us to include space-charge regions in the model. We compare results obtained with the tight-binding and envelope-function approximations.

Tight binding

Envelope (radar)

10.1103/physrevb.43.4777

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Citations (92)

Proton-induced disorder in InP-based resonant tunneling diodes

Applied Physics Letters (1999)

Edward Jackson B. D. Weaver Alan Seabaugh J.P.A. van der Wagt Edward Beam

We have fabricated arrays of resonant tunneling diodes based on InP substrates for exposure at room temperature with fluences of 3 MeV protons up to 7×1014 H+/cm2. Proton fluences below about 1×1013 cm−2 have little effect on the resonant tunneling diode but higher fluences decrease the peak current and increase the valley current. We find that proton-induced changes in the operating parameters are qualitatively similar to the effects of doping the wells.

Tunnel diode

10.1063/1.124348

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Citations (6)

An 8-GHz bandwidth 1-GS/s GaAs HBT dual track-and-hold

J.P.A. van der Wagt Mesfin Teshome

A track-and-hold is a critical sub-circuit of a wideband pipelined ADC. A 1-GS/s fully differential dual track-and-hold circuit fabricated in an 80-GHz f/sub T//fax, GaAs HBT production process exhibits an input bandwidth of 8.4 GHz (0.5 V/sub pp/) and 9.3 GHz (small signal). Total harmonic distortion is -59 dB for 1-Vpp 1-GHz input, and -42 dB for 0.5-V/sub pp/ 5-GHz input. The chip occupies 0.9 mm/spl times/1.8 mm active area and consumes 2.2 W from /spl plusmn/5 V.

Heterojunction bipolar transistor

Wideband

10.1109/vlsic.2001.934243

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Citations (6)

A monolithic 4 bit 2 GSps resonant tunneling analog-to-digital converter

T.P.E. Broekaert B. Brar J.P.A. van der Wagt Alan Seabaugh T. S. Moise

The combination of resonant tunneling diodes (RTDs) and heterostructure field-effect transistors (HFETs) provides a versatile technology for implementing microwave digital and mixed-signal applications. Here we demonstrate the first monolithic flash RTD/HFET analog-to-digital converter (ADC). The first pass ADC achieved 2.7 effective bits at 2 GSps. The one bit quantizer achieved a single tone spurious free dynamic range (SFDR) of greater than 40 dB at 2 GSps for a 220 MHz single tone input with dithering.

Spurious-free dynamic range

Dither

Analog-to-digital converter

4-bit

Flash ADC

10.1109/gaas.1997.628266

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Citations (20)

Tunnelling-based SRAM

Nanotechnology (1999)

J.P.A. van der Wagt

This paper describes the use of low-current-density tunnelling devices to obtain dense low-power (sub-100 nW/bit) compound semiconductor static random access memory (SRAM); this cell power is over two orders of magnitude lower than the best previously demonstrated in III-V materials. This same circuit topology promises orders of magnitude reduction in static power dissipation for silicon memories, assuming a suitable Si-based negative differential resistance device, at sub-pA current levels, is developed.

10.1088/0957-4484/10/2/312

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Citations (52)

Simulation of RHEED intensity oscillations during MBE growth

Journal of Crystal Growth (1993)

J.P.A. van der Wagt J. S. Harris

We develop a quantitative model for computation of the RHEED signal intensity during epitaxial growth. The growth surface is described in a way that naturally allows for tilted substrates. Oscillations in the computed RHEED signal during MBE growth exhibit a very fast decay. We are able to identify the fast initial rise of the signal after stopping growth with disappearing single atoms, and the slower subsequent recovery with growing terrace sizes.

SIGNAL (programming language)

Intensity

Terrace (agriculture)

10.1016/0022-0248(93)90782-r

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Citations (3)