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Fabrication security and trust of domain-specific ASIC processors

Summary

Application specific integrated circuits (ASICs) are commonly used to implement high-performance signal-processing systems for high-volume applications, but their high development costs and inflexible nature make ASICs inappropriate for algorithm development and low-volume DoD applications. In addition, the intellectual property (IP) embedded in the ASIC is at risk when fabricated in an untrusted foundry. Lincoln Laboratory has developed a flexible signal-processing architecture to implement a wide range of algorithms within one application domain, for example radar signal processing. In this design methodology, common signal processing kernels such as digital filters, fast Fourier transforms (FFTs), and matrix transformations are implemented as optimized modules, which are interconnected by a programmable wiring fabric that is similar to the interconnect in a field programmable gate array (FPGA). One or more programmable microcontrollers are also embedded in the fabric to sequence the operations. This design methodology, which has been termed a coarse-grained FPGA, has been shown to achieve a near ASIC level of performance. In addition, since the signal processing algorithms are expressed in firmware that is loaded at runtime, the important application details are protected from an unscrupulous foundry.
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Summary

Application specific integrated circuits (ASICs) are commonly used to implement high-performance signal-processing systems for high-volume applications, but their high development costs and inflexible nature make ASICs inappropriate for algorithm development and low-volume DoD applications. In addition, the intellectual property (IP) embedded in the ASIC is at risk when fabricated in...

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Waveguide engineering for hybrid Si/III-V lasers and amplifiers

Published in:
CLEO: Conf. on Lasers and Electro-Optics, 6-11 June 2012.

Summary

Using adiabatic tapers, hybrid silicon / III-V lasers and amplifiers are integrated with conventional thin (t = 0.25 um) silicon waveguides. Amplifiers have ~12 dB intrachip gain, and similar lasers have thresholds of 35 mA.
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Summary

Using adiabatic tapers, hybrid silicon / III-V lasers and amplifiers are integrated with conventional thin (t = 0.25 um) silicon waveguides. Amplifiers have ~12 dB intrachip gain, and similar lasers have thresholds of 35 mA.

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Photonic ADC: overcoming the bottleneck of electronic jitter

Summary

Accurate conversion of wideband multi-GHz analog signals into the digital domain has long been a target of analog-to-digital converter (ADC) developers, driven by applications in radar systems, software radio, medical imaging, and communication systems. Aperture jitter has been a major bottleneck on the way towards higher speeds and better accuracy. Photonic ADCs, which perform sampling using ultra-stable optical pulse trains generated by mode-locked lasers, have been investigated for many years as a promising approach to overcome the jitter problem and bring ADC performance to new levels. This work demonstrates that the photonic approach can deliver on its promise by digitizing a 41 GHz signal with 7.0 effective bits using a photonic ADC built from discrete components. This accuracy corresponds to a timing jitter of 15 fs - a 4-5 times improvement over the performance of the best electronic ADCs which exist today. On the way towards an integrated photonic ADC, a silicon photonic chip with core photonic components was fabricated and used to digitize a 10 GHz signal with 3.5 effective bits. In these experiments, two wavelength channels were implemented, providing the overall sampling rate of 2.1 GSa/s. To show that photonic ADCs with larger channel counts are possible, a dual 20- channel silicon filter bank has been demonstrated.
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Summary

Accurate conversion of wideband multi-GHz analog signals into the digital domain has long been a target of analog-to-digital converter (ADC) developers, driven by applications in radar systems, software radio, medical imaging, and communication systems. Aperture jitter has been a major bottleneck on the way towards higher speeds and better accuracy...

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Thermally tuned dual 20-channel ring resonator filter bank in SOI (silicon-on-insulator)

Published in:
CLEO 2011, Conf. on Lasers and Electro-Optics, 1 May 2011.

Summary

Two 20-channel second-order optical filter banks have been fabricated. With tuning, the requirements for a wavelength multiplexed photonic AD-converter (insertion loss 1-3 dB, extinction >30 dB and optical bandwidth 22-27 GHz) are met.
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Summary

Two 20-channel second-order optical filter banks have been fabricated. With tuning, the requirements for a wavelength multiplexed photonic AD-converter (insertion loss 1-3 dB, extinction >30 dB and optical bandwidth 22-27 GHz) are met.

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30 to 50 ns liquid-crystal optical switches

Published in:
Optics Express, Vol. 18, No. 18, 30 August 2010, pp. 1886-18893.

Summary

The optical switching time of twisted-nematic liquid-crystal cells using the liquid crystals, 5CB (C,H,,-Ph-Ph-CN), 50CB(C,Hw O-Ph-Ph-CN) and PCH5 (C,H,,-Cy-Ph-CN) have been characterized as a function of temperature, prebias voltage and switching voltage, V. The transition time from 90 % to 10 % transmission scales as V-1.9 and is limited to 30 to 50 ns by the liquid-crystal breakdown electric field, - 100 V I'm-I The time fi-om the initial switching voltage step to 90 % transmission, delay time, decreases with increasing prebias and switching voltage. For 5CB and 50CS the delay time approaches a constant value at higher electric fields, >10 V ~1Il,-1. Both the transition and delay times decrease with increasing temperature. The minimum transition time at temperatures a few degrees below the nematicisotropic temperature are 32, 32, and 44 ns and delay times are 44, 25 and 8 ns for 5CB, 50CB, and PCH5 respectively.
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Summary

The optical switching time of twisted-nematic liquid-crystal cells using the liquid crystals, 5CB (C,H,,-Ph-Ph-CN), 50CB(C,Hw O-Ph-Ph-CN) and PCH5 (C,H,,-Cy-Ph-CN) have been characterized as a function of temperature, prebias voltage and switching voltage, V. The transition time from 90 % to 10 % transmission scales as V-1.9 and is limited to...

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Operation and optimization of silicon-diode-based optical modulators

Published in:
IEEE J. Sel. Top. in Quantum Electron., Vol. 16, No. 1, January/February 2010, pp. 165-172.

Summary

An optical modulator in silicon based on a diode structure has been operated in both forward and reverse bias. This modulator achieves near state-of-the-art performance in both modes, thereby making this device idea for comparing the two modes of operation. In reverse bias, the device has a V[pi]L of 4.9 V-cm and a bandwidth of 26GHz. In forward bias, the device is very sensitive, a V[pi]L a slow as 0.0025 V-cm has been achieved, but the bandwidth is only 100 MHz. A ndw geometyr for a reverse-bias device is proposed, and it is predicted to achieve a V[pi]L of 0.5V.cm.
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Summary

An optical modulator in silicon based on a diode structure has been operated in both forward and reverse bias. This modulator achieves near state-of-the-art performance in both modes, thereby making this device idea for comparing the two modes of operation. In reverse bias, the device has a V[pi]L of 4.9...

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CMOS-compatible dual-output silicon modulator for analog signal processing

Summary

A broadband, Mach-Zehnder-interferometer based silicon optical modulator is demonstrated, with an electrical bandwidth of 26 GHz and V[pi]L of 4 V·cm. The design of this modulator does not require epitaxial overgrowth and is therefore simpler to fabricate than previous devices with similar performance.
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Summary

A broadband, Mach-Zehnder-interferometer based silicon optical modulator is demonstrated, with an electrical bandwidth of 26 GHz and V[pi]L of 4 V·cm. The design of this modulator does not require epitaxial overgrowth and is therefore simpler to fabricate than previous devices with similar performance.

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Effect of carrier lifetime on forward-biased silicon Mach-Zehnder modulators

Summary

We present a systematic study of Mach-Zehnder silicon optical modulators based on carrier-injection. Detailed comparisons between modeling and measurement results are made with good agreement obtained for both DC and AC characteristics. A figure of merit, static VpiL, as low as 0.24Vmm is achieved. The effect of carrier lifetime variation with doping concentration is explored and found to be important for the modulator characteristics.
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Summary

We present a systematic study of Mach-Zehnder silicon optical modulators based on carrier-injection. Detailed comparisons between modeling and measurement results are made with good agreement obtained for both DC and AC characteristics. A figure of merit, static VpiL, as low as 0.24Vmm is achieved. The effect of carrier lifetime variation...

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All silicon infrared photodiodes: photo response and effects of processing temperature

Summary

CMOS compatible infrared waveguide Si photodiodes are made responsive from 1100 to 1750 nm by Si+ implantation and annealing. This article compares diodes fabricated using two annealing temperatures, 300 and 475C. 0.25-mm-long diodes annealed to 300C have a response to 1539 nm radiation of 0.1 A W-1 at a reverse bias of 5 V and 1.2 A W-1 at 20 V. 3-mm-long diodes processed to 475C exhibited two states, L1 and L2, with photo responses of 0.3 +/-0.1 A W-1 at 5 V and 0.7 +/-10.2 A W-1 at 20 V for the L1 state and 0.5 +/-0.2 A W-1 at 5 V and 4 to 20 A W-1 at 20 V for the L2 state. The diodes can be switched between L1 and L2. The bandwidths vary from 10 to 20 GHz. These diodes will generate electrical power from the incident radiation with efficiencies from 4 to 10 %.
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Summary

CMOS compatible infrared waveguide Si photodiodes are made responsive from 1100 to 1750 nm by Si+ implantation and annealing. This article compares diodes fabricated using two annealing temperatures, 300 and 475C. 0.25-mm-long diodes annealed to 300C have a response to 1539 nm radiation of 0.1 A W-1 at a reverse...

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A high-power MEMS electric induction motor

Published in:
J. Microelectromech. Syst., Vol. 13, No. 3, June 2004, pp. 465-471.

Summary

An electric induction micromotor with a 4-mm-diameter rotor was designed and built for high-power operation. Operated at partial actuating voltage, the motor has demonstrated an air gap power in excess of 20 mWand torque of 3 5 Nmat speeds in excess of 55 000 rpm. Operation at higher power and speed was limited by bearing stability at higher rotational speeds. The device builds on an earlier micromotor demonstrated by Frechette et al. The high power of the present motor is enabled by its low-loss, high-voltage electric stator, which also offers improved efficiency. The development of this electromechanical device is an important enabling step not only for watt-scale micromotors, but also for the development of microelectric generators. This paper presents the motorαs design, the fabrication process that was created to meet its stringent design requirements, and its performance to date.
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Summary

An electric induction micromotor with a 4-mm-diameter rotor was designed and built for high-power operation. Operated at partial actuating voltage, the motor has demonstrated an air gap power in excess of 20 mWand torque of 3 5 Nmat speeds in excess of 55 000 rpm. Operation at higher power and...

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