5,773 research outputs found
Asynchronous techniques for system-on-chip design
SoC design will require asynchronous techniques as the large parameter variations across the chip will make it impossible to control delays in clock networks and other global signals efficiently. Initially, SoCs will be globally asynchronous and locally synchronous (GALS). But the complexity of the numerous asynchronous/synchronous interfaces required in a GALS will eventually lead to entirely asynchronous solutions. This paper introduces the main design principles, methods, and building blocks for asynchronous VLSI systems, with an emphasis on communication and synchronization. Asynchronous circuits with the only delay assumption of isochronic forks are called quasi-delay-insensitive (QDI). QDI is used in the paper as the basis for asynchronous logic. The paper discusses asynchronous handshake protocols for communication and the notion of validity/neutrality tests, and completion tree. Basic building blocks for sequencing, storage, function evaluation, and buses are described, and two alternative methods for the implementation of an arbitrary computation are explained. Issues of arbitration, and synchronization play an important role in complex distributed systems and especially in GALS. The two main asynchronous/synchronous interfaces needed in GALS-one based on synchronizer, the other on stoppable clock-are described and analyzed
The Inductive Single-Electron Transistor (L-SET)
We demonstrate a sensitive method of charge detection based on
radio-frequency readout of the Josephson inductance of a superconducting
single-electron transistor. Charge sensitivity ,
limited by preamplifier, is achieved in an operation mode which takes advantage
of the nonlinearity of the Josephson potential. Owing to reactive readout, our
setup has more than two orders of magnitude lower dissipation than the existing
method of radio-frequency electrometry. With an optimized sample, we expect
uncoupled energy sensitivity below in the same experimental scheme.Comment: 10 page
Charge sensitivity of the Inductive Single-Electron Transistor
We calculate the charge sensitivity of a recently demonstrated device where
the Josephson inductance of a single Cooper-pair transistor is measured. We
find that the intrinsic limit to detector performance is set by oscillator
quantum noise. Sensitivity better than e is
possible with a high -value , or using a SQUID amplifier. The
model is compared to experiment, where charge sensitivity e and bandwidth 100 MHz are achieved.Comment: 3 page
Accessing nanomechanical resonators via a fast microwave circuit
The measurement of micron-sized mechanical resonators by electrical
techniques is difficult, because of the combination of a high frequency and a
small mechanical displacement which together suppress the electromechanical
coupling. The only electromagnetic technique proven up to the range of several
hundred MHz requires the usage of heavy magnetic fields and cryogenic
conditions. Here we show how, without the need of either of them, to fully
electrically detect the vibrations of conductive nanomechanical resonators up
to the microwave regime. We use the electrically actuated vibrations to
modulate an LC tank circuit which blocks the stray capacitance, and detect the
created sideband voltage by a microwave analyzer. We show the novel technique
up to mechanical frequencies of 200 MHz. Finally, we estimate how one could
approach the quantum limit of mechanical systems
Fiscal forecasting: lessons from the literature and challenges
While fiscal forecasting and monitoring has its roots in the accountability of governments for the use of public funds in democracies, the Stability and Growth Pact has significantly increased interest in budgetary forecasts in Europe, where they play a key role in the EU multilateral budgetary surveillance. In view of the increased prominence and sensitivity of budgetary forecasts, which may lead to them being influenced by strategic and political factors, this paper discusses the main issues and challenges in the field of fiscal forecasting from a practitionerâs perspective and places them in the context of the related literature. JEL Classification: H6, E62, C53Fiscal policies, forecasting, government budget, monitoring
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