Ground noise

Abstract: Here, it is assumed that the internal switching current is small compared to the output driver switching current. In the past, it was assumed that simultaneous switching noise created by CMOS outputs was directly proportional to the number of outputs switching simultaneously. Recent studies indicate that CMOS circuits exhibit sublinear behavior (due to the negative feedback influence) of power/ground noise (or bounce) as a function of the number of outputs switching simultaneously. Detailed electrical models, equations, and a trial architecture for calculating the switching noise are included. The results are compared to SPICE simulations and conventional power/ground noise calculations. The behavior of simultaneous switching noise as a function of constant-voltage (CV) device scaling is explained for small-geometry CMOS output drivers. >

Abstract: A contactor assembly for testing electronic devices that are packaged with a dual-in-line pin array has an insulating base that mounts two rows of contacts, each adapted to flex into electrical connection with a pin of the device, and a pair of flexible ground planes each spaced closely from an associated one row of said contacts. A flexible, insulating spacer maintains the ground planes and their associated row of contacts with a substantially fixed spacing there between during the flexural movement of said contacts. In the preferred form, the upper edge of the ground planes adjacent the pins includes an arrangement for securing a chip electornic device, a capacitor or a resistor. The other end of the chip mounts a contact tip that makes electrical connection with an associated pin when the associated contact also connects with the pin. The signal path provided by the holder, chip and tip is extremely short, preferably less than 0.150 inch. The contacts and ground planes electrically surface mount on a contactor board. Flexible lower end portions of the contacts and ground planes make direct electrical connection with signal pads and ground planes on the board without the use of connectors. A flexible mount formed by strips of a conductive material having arms soldered to two or more contacts hold a surge capacitor that decouples the device from ground noise during large current surges.

Abstract: Design of noise detector circuits as compact as standard logic cells is proposed. High-density large-scale digital integrated circuits that embed such built-in noise detectors enable in-depth characterization of dynamic power supply and ground noises. Dependence of power supply and ground voltage drops on the location of active cell rows within 1.8-V standard cell-based digital circuits are consistently measured by 1.8- and 2.5-V built-in detectors fabricated in a 0.18-/spl mu/m CMOS triple-well technology. Measurements also show that ground noise distribution is distinctively more localized than power supply counterparts due to the presence of a substrate.

Abstract: An effective solution to the problem of the detection and identification of low-yield coupled and fully decoupled underground nuclear explosions appears available via use of high-frequency seismic data ranging up to 30 or 40 Hz. In order to evaluate detection-identification capabilities when using such data, it is necessary to estimate (1) spectral characteristics and relative amplitudes of both P and S waves from explosions and earthquakes over the frequency band from 5 to 40 Hz, (2) signal transmission characteristics over this band through pertinent types of earth structure, and (3) recording system and ground noise characteristics over this frequency band. In this study, each of these topics is considered in turn as they relate to detection and discrimination of the signals from low-yield coupled and decoupled explosions in the regional and teleseismic distance ranges. Estimates of the capabilities of specific hypothetical networks to detect and identify (insofar as signal-to-noise ratio is an important factor in identification) explosions within the USSR are then considered. These estimates of signal detection capability provide the central focus for the study as they serve to translate diverse and rather complex sets of observational data and theory into concrete predictions of monitoring capability. Following the assessment of detection capabilities, the problem of identification of small events is considered, with particular emphasis on discrimination at regional distances where the network is calculated to provide signals of high signal-to-noise ratio. The principal results and conclusions of this study are as follows: (1) seismic system noise can be suppressed to levels well below ground noise at quiet sites up to frequencies at least as high as 30–40 Hz when using presently available hardware; (2) average amplitudes of high-frequency noise in a variety of geological environments are very low and change little with time or season; (3) transmission of high-frequency P and S wave signals in the regional distance range in stable continental areas and shields is nearly as efficient as at 1 Hz, with effective Q factors in shield areas being about 9000 and 4000 for high-frequency Pn and Sn, respectively, while the effective Q for Pn waves in tectonic areas is about 1000; (4) a properly designed and deployed network of 25 simple three-component nonarray stations internal to the USSR and 15 similar stations surrounding the USSR is predicted to be capable of multistation detection at high signal-to-noise ratio of fully decoupled 1-kt explosions located at all potential decoupling sites within the USSR; (5) by inference from the quantitative agreement of empirical observations and theoretical predictions, when using lower-frequency data over a great range of explosion yields, we conclude that procedures based on the use of both detectable P and S waves will serve to identify explosion-generated seismic signals at least as small as those expected from a fully decoupled 1-kt explosion.