Rise time

About: Rise time is a research topic. Over the lifetime, 4748 publications have been published within this topic receiving 47512 citations.

Method and apparatus for programmable adjustment of computer system bus parameters

Abstract: A system for programmatically adjusting electrical characteristics of a bus interface so as to modify bus operating and signaling parameters employs a control module or mechanism, responsive to a digital signal, for setting the characteristic's value. The electrical characteristic can be a voltage determinative, for example, of any of the following bus operating and signaling parameters: driver output rise time, driver output fall time, driver voltage limits, driver propagation time, receiver threshold voltage levels, or termination resistance. The digital signal can be generated, for example, by a computer-executable program, a controller, or other such device, that applies the digital signal to the control mechanism, for example, via a JTAG interface/controller.

Analysis of Subpicosecond Full-Switching with a Symmetric Mach-Zehnder All-Optical Switch

Abstract: We present subpicosecond full-switching with a symmetric Mach-Zehnder all-optical switch. To the best of our knowledge, this is the fastest all-optical switching experiment with incoherent and thus realistic, efficient optical nonlinearities. We discuss various factors which possibly limit the switching speed. Present switching speed is determined only by the rise time of interband carrier excitation. Our analysis suggests that by reducing the duration of the control pulse, faster switching in the range from 100 to 200 fs can be expected, in which control pulse broadening due to group velocity dispersion is the dominant limitation.

Charge Waveform of a New Two-Dimensional Position-Sensitive Silicon Detector

Abstract: The operation principles of the two-dimensional position-sensitive silicon detector newly developed by Doke et al. were studied using a simple model. This model treats the detector as an area of continuously distributed capacitance C and resistance Rs of position surface layer. A linear relationship can then be obtained between the position of the incident particle and change collected at the contacts of the detector. The kinetics of charge collected at corner contacts, ballistic deficit and noise were calculated. Rise time of the charge pulse (10–90%) was found to vary with the position of incidence up to about RsC/8. It was found that a shaping time constant longer than RsC/3 is required for pulse shaping with single CR-differentiation and single CR-integration in order to obtain a ballistic deficit of less than 1%.

A resonance dynamical approach to faster, more reliable micromechanical switches

Abstract: The resonance and nonlinear dynamical properties of micromechanical structures have been harnessed to demonstrate an impacting micromechanical switch with substantially higher switching speed, better reliability (even under hot switching), and lower actuation voltage, all by substantial factors, over conventional RF MEMS switches. The particular resoswitch implementation demonstrated in this work comprises a wine-glass mode disk resonator, driven hard via a 2.5V amplitude ac voltage at its 61-MHz resonance frequency so that it impacts electrodes along an orthogonal switch axis, thereby closing a switch connecting a signal through switch axis electrodes. The 61-MHz operating frequency corresponds to a switching period of 16ns with an effective rise time of ~4ns, which is more than 50 times faster than the mus-range switching speeds of the fastest conventional (non-resonant) RF MEMS switches. Furthermore, with the signal on during switching, a capacitive version of the switch has hot switched for more than 16.5 trillion cycles without failure, which is substantially more than the 100 billion cycles normally posted by conventional RF MEMS switches. The reliability of the present resoswitch benefits from the high stiffness of its actuating disk resonator, which provides a large restoring force with which to overcome sticking forces; and from the energy stored via resonance vibration that provides a momentum that further increases the effective restoring force. Resonance operation in turn allows the actuation voltage amplitude to be a mere 2.5V, despite the large spring restoring force. Such mechanically resonant switches (dubbed ldquoresoswitchesrdquo) used in place of the switching transistors in switched-mode power converters and power amplifiers stand to greatly enhance efficiencies by allowing the use of much higher power supply voltages than allowable by transistors.

Fast rise time booting circuit

Abstract: A circuit is disclosed for generating a two-stage boot signal, the first stage being a transition from a low voltage to a high voltage, and the second stage being a transition from the high voltage to an increased high voltage. The first stage operates to read the contents from a memory cell, and the second stage operates to restore the contents of the access memory cell. A capacitor (102) is charged with a voltage to boost the output (122) of the circuit (52) in order to produce the increased high voltage. However, the lower plate (100) of the capacitor (102) is effectively disconnected from the circuit during the transition from a low to high voltage in order to provide a fast transition period.