Measurement Of Propagation Delay Research Articles

On-chip process variation-tracking through an all-digital monitoring architecture

In sub-nanometer complementary metal oxide semiconductor (CMOS) technologies, process variability strongly affects the fabrication yield. To face this problem, post-silicon adaptive approaches have been proposed as a promising solution. However, their actual implementation requires the availability of effective monitoring architectures that can sense and sample process variation across the die. In this study, the authors present a sensor circuit for capturing on-chip variations owing to the fabrication process. The proposed solution is based on the concept of ‘variation amplification’ and uses the propagation delay measurement through a pass-transistor chain. Our monitor architecture, which consists of a self-contained cell containing N- and P-type sensors along with an all-digital delay measurement circuitry, is able to capture local variations of negative metal oxide semiconductors and positive metal oxide semiconductors transistors individually, therefore enabling fine tuning of the circuit. The authors also propose an array-based integration of the monitors, where the sensors are placed in a different location of the die and connected together with the scan–chain to distribute the sampled data. Detailed SPICE level simulations conducted on an industrial 45-nm CMOS technology demonstrate the sensing capability of the proposed architecture and the effectiveness of the on-chip all-digital measurement process.

Statistics of light transport in 235-ring silicon coupled-resonator optical waveguides

In contrast to recent reports of localization-impaired transport in long slow-light waveguides, we demonstrate light transport in silicon coupled-resonator optical waveguides (CROWs) consisting of up to 235 coupled microrings without localization over frequency bands that are several hundred gigahertz wide. Furthermore, from the unique statistical signatures provided by time-domain propagation delay measurements, we demonstrate the spectrally correlated nature of light propagation in CROWs.

Estimation Method of Rotation Parameters of a Small Planetary Body and Position of a Rover Based on Measurements of Round-trip Propagation Delay

Estimation Method of Rotation Parameters of a Small Planetary Body and Position of a Rover Based on Measurements of Round-trip Propagation Delay

Optical time-of-flight measurement based on data transmission in a ring oscillator

We introduce a novel optical propagation delay measurement scheme for distance estimation. It is based on a ring oscillator in which the oscillation signal is replaced by the clock information contained in optical data. A clock-and-data recovery can recover the oscillation signal at the receive end. Correlation of the received pattern with the transmitted pattern and a measurement of the bit duration by a frequency counter allow to determine the distance. The scheme has been realized at 1550 nm wavelength, using an externally modulated laser, a commercial 155.52 Mb/s clock-and-data recovery and a field-programmable gate array. Short-term repeatability is <10 microm at an equivalent free-space distance of 72 m. Measurement interval is 0.1 s. At 3 km distance the relative repeatability is 8.10(-8). The readout can be corrected with measured temperature data.

Wireless Location Uses Geometrical Transformation Method With Single Propagation Delay: Model and Detection Performance

Inspired by recent promotions of wireless location services and applications, this paper develops a simple model for detecting a mobile caller location with low implementation complexity and promising accuracy. The model that is described in this paper employs the geometrical transformation method with single propagation delay measurement. Depending on the number of available surrounding base transceiver stations (BTSs), a set of the pseudodistances and pseudodistance differences is provided through the geometrical distances between the home and multiple foreign BTSs, which is called the geometrical transformation method. Accordingly, the mobile caller location can be detected using the circular location technique and the hyperbolic location technique. The major benefit of the proposed model is that during a call to detect the mobile caller's location, the use of geometrical transformation allows us to overcome the location handover problem. A forcing handover in a global system for mobile communications (GSM) network or a three-way soft handover in a universal mobile telecommunications system (UMTS) network, for example, occurs when detecting the location when a standard model that is based on the measurement of the propagation delay is utilized. Comparing the standard model with the proposed model, the former needs at least three propagation delays that were simultaneously measured from at least three BTSs, whereas the latter needs only a single propagation delay that was measured from the home BTS. Moreover, in the case where we do not have a priori information of a non-line-of-sight (NLOS) error, a deterministic parameter that is related to the propagation delay is defined. This parameter is shown as limited a priori information for calibrating the coarse resolution in the proposed location model, which is caused by the NLOS error. To have significant findings, we conduct a practical experiment in an urban environment based on a 1.8-GHz commercial cellular network. In the five-BTS case where the location error is less than 300 m, the probability of location error that the proposed model with a bit period of 1/2 achieved is greater than 0.85. Although the performance of the proposed location model does not satisfy the U.S. Federal Communications Commission Enhanced 911 (FCC E-911) requirements, it is a good solution for the deployment of wireless location services and applications.

Direct measurements of propagation delay of single-flux-quantum circuits by time-to-digital converters

Direct measurements of propagation delay of single-flux-quantum (SFQ) circuits were performed using SFQ double-oscillator time-to-digital converters. The propagation delay of several SFQ logic gates in our cell library named CONNECT were measured in picosecond resolution. Small discrepancy in the propagation delay of picosecond level was observed between measurement and circuit simulation results. The discrepancy is well explained assuming the parasitic inductance around shunt resistors of Josephson junctions.

A measurement of propagation delay

A measurement method and associated uncertainty analysis have been developed for the measurement of propagation or group delay in electrical transmission lines and optical fibres. The measurement method and uncertainty analysis were applied to measurements of optical fibre delay lines that introduce tens of microseconds of delay (1 km, 2 km and 4 km fibre lengths) and trombone lines that introduce sub-nanosecond delays. For the measurement method described here, uncertainties in the measured delay are as low as 90 fs (95% confidence interval) for a propagation delay of 660 ps and less than 200 ps (95% confidence interval) for a propagation delay of 20 µs.

Acoustic propagation delay measurements using transmission of known broad bandwidth waveforms

A system and method in which one or more acoustic projectors transmit broad bandwidth waveforms having known characteristics, and one or more acoustic receivers detect the transmitted waveforms, with the measurement of a propagation time from the projectors to the receivers being based on knowledge of the transmitted waveforms. The measurements are performed such that there is a low probability that other third party receivers will detect the transmission. The measurements may also be performed in an environment supporting multiple propagation paths. The system and method may further measure the Doppler shift induced by relative motion between the acoustic projector and the acoustic receiver.

The measurement of propagation delay in multimode optical fibre with pulse-reflection-oscillation method

Using the pulse-reflection-oscillation method, a high precision optical fibre propagation delay measurement system is made and applied to measure multimode optical patchcords of four different lengths (10, 20, 50 and 100 m ). The result shows that the standard deviation is less than 11 ps .

Location of mobile terminals using time measurements and survey points

Mobile terminal location has attracted much interest for its applications in emergency communications, location-sensitive browsing, and resource allocation. The paper introduces the use of nonparametric kernel-based estimators for location of mobile terminals using measurements of propagation delays. It is demonstrated that these estimators perform better than the previously used parametric maximum likelihood estimators for the case of a simulated microcell environment with line-of-sight (LOS) and non-line-of-sight (NLOS) radio propagation at several different levels of measurement noise. Their performance is not greatly degraded by NLOS effects. Methods for calculating good values for parameters of the kernel functions are demonstrated, as well as the robustness of the estimators when the values of the parameters vary from the optimal points. A lower bound on the mean square error of location estimation that considers the transition between LOS to NLOS propagation over short distances is presented. It is demonstrated the proposed location estimation method comes close to meeting this bound.

Reduction of Number of Paths to be Tested in Delay Testing

Delay testing is important for high speed ICs. The main difficulty in delay testing comes from the huge number of paths and the large percentage of delay untestable paths. Therefore, it is critical to reduce the number of paths to be tested in delay testing. This paper presents two approaches to delay testing with significant reduction of number of paths to be tested, which provide high path delay fault coverage by testing a small number of paths. In the first approach, it is necessary to sample the primary output twice, one before and another after the transition for each test pair. The second approach is by means of accurate measurement of delays of very limited number of paths. In order to make this approach feasible, the paper also introduces a new concept of path sensitization, termed single-transition sensitization, to allow direct measurement of propagation delay of those paths. The paper presents how to select the very limited number of paths, termed sample paths, and how to generate test pairs and observation times for the sample paths for the first approach. On the other hand, it is noted for the second approach that under the analytical delay model (Proc. 9th International Conf. on VLSI Design, Bangalore, India, Jan. 1996, pp. 162–165), most of the paths are delay testable, which makes the accurate measurement approach feasible. In fact, it would be very difficult to select sample paths based on single path sensitization as it was done in (IEEE Trans. on Computers, Vol. c-29, No. 3, pp. 235–248, March 1980). The paper shows that the number of sample paths is linear to the number of gates in the circuit under test, despite exponential growth in the number of single paths.

Phase measurement of light absorption and scatter in human tissue

Analog and digital technologies are presented for precise measurement of propagation delay of photons from source and detector placed on portions of the human body. The goal of the apparatus design is to quantify absorption (μa) and scattering (μs′) induced by biological pigments and biological structures, respectively. Body tissues are highly scattering with a mean distance between scatterers of less than a mm (at 700–850 nm). Significant absorption is mainly due to 5%–10% of the tissue volume occupied by blood. Measurement of μa and μs′ is done by both time and frequency domain equipment. This article focuses upon frequency domain equipment because of its simplicity, reduced noise bandwidth, versatility, and the strong analogy to very high frequency/ultrahigh frequency communication devices, particularly those using phase modulation. Comparisons are made of homodyne and heterodyne systems together with evaluation of single and multiple side band systems, with particular emphasis on methods for multiplexed optical and radio frequencies by frequency encoding or time-sharing technologies. The applications of these phase modulation systems to quantitative brain and muscle blood oximetry, functional activity of the forebrain, and other important problems of medical science, are presented.

Non-contact probing of high speed microelectronics using electrostatic force sampling

The ability to perform non-invasive high-frequency measurements at the internal points of an integrated circuit is important for the design and failure analysis of advanced microelectronics. As integrated circuit densities and speed increase, obtaining information on their internal operation becomes extremely difficult using conventional probing methods due to parasitic loading and low spatial resolution. We present a non-contact probing technique based on a nonlinear Coulomb force interaction for extracting high-frequency signals at internal points of an integrated circuit. Internal circuit voltages are measured by sensing the local electrostatic force on a small micromachined probe that is held in close proximity to the circuit measurement point. The bandwidth of force measurements made using proximal probes are typically limited by the mechanical frequency response of the probe. In the presented instrument high frequency waveform measurements are enabled by using a pulse sampled heterodyne technique. The probing instrument has a bandwidth of 3 GHz and is capable of internal circuit delay measurements with a resolution of less than 10 ps. Measurement of the internal propagation delays and rise times of a complementary metal-oxide-semiconductor inverter chain are given.

An investigation of time transfer accuracies over a utility microwave communications channel

Measurements made on an electric utility timekeeping system using standard IRIG-B time code and commercially available equipment are discussed. An attempt is made to determine whether this technique can reliably transfer time accuracies of one millisecond and accuracies of 5 to 50 microseconds. A new method of propagation delay measurement using two synchronized time code generators is introduced. These measurements are compared with predictions of delay and measurements made with a commercial communications test set used in a new manner. Discussion of the differences between the methods is given. >

Urban multipath propagation delay characteristics in mobile communications

In this paper, propagation delay measurements were carried out in Tokyo (metropolitan urban area) where high rises and other buildings are concentrated on a plane and in Kofu (urban area adjacent to mountains) surrounded by tall mountains. The delay characteristics such as delay spread and wave numbers were found. The principal results obtained in these areas are as follows. (1) In a metropolitan urban area, i.e., Tokyo, (a) the average delay spread in a high-density residential district is less than about 1 μs and the delay profile consists of a group of direct waves arriving directly from the base station; and (b) the average delay spread in a location with high-rise buildings is also less than 1 μs and the average number of arriving waves is about five with the delay profile consisting of a direct wave group and a reflected wave group from reflecting object. (2) In an urban area adjacent to mountains, i.e., Kofu, the average delay spread is less than about 2 μs and the average number of arriving waves is four. The delay profile consists of a direct wave group and a reflected wave group. The level of the reflected wave group decreases exponentially with the delay time in the case of reflection from buildings, while the level is almost constant within a certain range of delay time and is of a spread shape (rectangular) in the case of reflection from mountains. From these measured results, a simple propagation model consisting of a direct wave group and a reflected wave group is proposed. It is shown that the distance dependence of the delay spread has a peak between the base station and a reflecting object.

Backside optical measurements of picosecond internal gate delays in a flip-chip packaged silicon VLSI circuit

A report is presented of the backside optical measurements of internal gate propagation delays in a flip-chip mounted silicon integrated circuit. Both gate delays and risetimes agreed well with prior simulations. However, the measurements displayed additional features on the signals that were not seen in the simulations, such as feedforward through devices, signal over/undershoot, and circuit switching noise on the power supply. >

Measurement of multigigahertz waveforms and propagation delays in modulation-doped field-effect transistors using phase-space absorption quenching

High-speed waveforms (up to 20 GHz) in InGaAs/InAlAs modulation-doped field-effect transistors (FETs) are measured using 10–20 ps optical probe pulses via the quenching of the absorption in the quantum well gate channel due to Pauli exclusion. The technique is a noncontact probe of the charge density in the gate, and hence, of the logic state of the FET. This charge-sensitive probing technique is combined with voltage-sensitive electro-optic sampling to study internal dynamics of the FET. A gate channel charging time of 11 ps and a gate to drain propagation delay of 15 ps are measured.

The influence of the transit-time effect on propagation delay measurements by electron and photon beam techniques

Propagation delay measurements of high-speed digital devices require high accuracy and excellent stability. At the same time, long-range phase shifts are necessary because signals in these circuits may have very long periods. This can be achieved with a newly developed phase shift method, where a blanking capacitor acts as a gate to select one out of a larger number of pulses. A delay of several hundred nanoseconds with picosecond accuracy was demonstrated with this technique. Ultimately, the resolution of propagation delay measurements is limited by variations in the secondary electron transit time. This leads to a shift of the measured waveform, depending on the test point geometry. Errors then result if the propagation delay is measured between points of different dimensions. This effect was evaluated theoretically and experimentally. A difference in conductor width between two test points of a factor of 2 was found to lead to an error of 3ps for propagation delay measurements.

Propagation Delay Measurements from a Timing Sampler Intended for Use in Space

This paper describes a 3-μm CMOS timing sampler which is a test circuit designied inito the JPL CRRES chip to be flown on the Coombined Release and Radiation Effects Satellite (CRRES). The timing sampler consists of 64 inverter-pair stages with sampling latches anid decoder circuitry. The sampler is used to measure inverter-pair propagation delays, which are nominally 2.5 nanoseconds, with a resolutioni of 100 picoseconds. A simple model was developed to explain the radiation-induced inverter-pair delay shifts in terms of radiation-induced MOSFET-threshold voltage shifts and effective nodal capacitances. The magnitude of the shift in pair delay with radiation was estimated at the point where the n-MOSFET threshold voltage became zero. For a 0.7-volt threshold shift, the pairdelay increased from its preradiation value by 360 picoseconds for a rising step iniput and decreased by 190 picoseconds for a falling step input.

Measurement of on-chip waveforms and pulse propagation in digital GaAs integrated circuits by picosecond electro-optic sampling

We demonstrate precise measurement of sub-100 ps rise time on-chip electrical waveforms and of pulse propagation in digital GaAs integrated circuits with the use of picosecond electro-optic sampling. These experiments yield the first non-invasive measurement of single-gate propagation delays via direct and precise observation of on-chip waveforms at the input and output of individual logic gates internal to an integrated circuit.