Passive Delay Research Articles

Design and characterization of low loss 50 picoseconds delay line on SOI platform

We design and experimentally demonstrate 50 picoseconds (ps) low loss delay line on 300 nm SOI platform. The delay line unit consists of straight rib waveguide and strip bend section linked by a transition taper waveguide. Low propagation loss of ~0.1 dB/cm is achieved on the straight rib waveguide. With taking into account both low loss and desirable delay, a complete design and characterization process for passive delay line is presented. Our measurement results show that about 0.7 dB excess loss is achievable for 50 ps delay. The loss can be further reduced by adjusting the layout parameters.

DNA Aβ42 Vaccination as Possible Alternative Immunotherapy for Alzheimer Disease

Immunotherapy for Alzheimer disease was advanced in reports1,2 showing that the use of Aβ42 peptide vaccination in a transgenic mouse model of Alzheimer disease significantly reduced the Aβ42 plaque count, significantly reduced levels of gliosis, and significantly improved behavior. Based on the positive experimental animal model data, a human Aβ42 peptide immunization clinical trial [ie, the AN1792(QS-21)-201 trial]3 for patients with Alzheimer disease was conducted; however, it was stopped owing to significant adverse effects in 6% of immunized patients. Subsequent studies showed that there were significant reductions in Aβ42-containing plaque in the brain but that the patients continued to become more demented.4 For patients with mild Alzheimer disease, the use of passive immunotherapy with the humanized monoclonal antibody bapineuzumab resulted in no significant clinical benefit, but the use of passive immunotherapy with the humanized monoclonal antibody solanezumab resulted in some memory and behavioral benefits (New York Times, July 24, 2012). Intravenous immunoglobulins, which probably contain anti-Aβ antibodies, have also been used to treat patients with Alzheimer disease, and their use has resulted in clinical stabilization.5

Compact passive and active tunable delay lines using complementary split‐ring resonators

A novel compact left-handed delay line using four-cell of complementary split-ring resonators (CSRRs) has been designed, fabricated and characterised. It is found that the cell separation of CSRRs has significant effects on time delay. To obtain maximum time delay, each cell separation must be individually tuned and optimised. The results show that cell separation optimisation can prolong the delay time from 0.6 to 6.08 ns, increased by more than 90%. Furthermore, varactor diodes were embedded in the delay line to provide tunability. It is verified experimentally that the delay time can be tuned from 0.08 to 5.6 ns by varying DC bias from 0 to −20 V. In addition, a new equivalent circuit model has been developed and verified both numerically and experimentally, to take into account of the magnetic coupling between the rings in the adjacent cells, which has been neglected so far in published works. The proposed analysis reveals that such magnetic coupling can be sometimes very strong and has significant effects on circuit performance.

Preserved Spatial Memory for Reaching to Remembered Three-Dimensional Targets in Aging

Background/Study Context: Compared with the large literature on the impact of aging on spatial memory span, far fewer studies have examined the influence of aging on spatial memory processes required to reach a remembered target. This study assessed the ability of seniors to accurately reach to three-dimensional (3D) memorized targets in four conditions in which the memory delay and the attentional demands varied. Methods: The accuracy and variability of reaching movements (3D absolute, 3D variable, and spatial component errors) were analyzed to evaluate the performance of 12 young adults aged 20 to 30 and 12 older adults aged 62 to 69 in the different delay conditions (short passive delay, long passive delay, long cognitive delay, and long spatial delay). Variance analyses were applied on each error measure as well as on kinematic features of the movements (movement time, deceleration time, and peak velocity). Results: Results revealed that older participants were as capable as their younger counterpart to maintain target location in memory regardless of task complexity. Conclusion: Although memory deficits have been found in older adults in several previous studies, the current results support the idea that healthy aging does not produce a breakdown in all memory tasks. Hence, a specific spatial memory channel seems to remain unaffected in normal aging.

Swept source / Fourier domain polarization sensitive optical coherence tomography with a passive polarization delay unit

Polarization sensitive optical coherence tomography (PS-OCT) is a functional imaging method that provides additional contrast using the light polarizing properties of a sample. This manuscript describes PS-OCT based on ultrahigh speed swept source / Fourier domain OCT operating at 1050nm at 100kHz axial scan rates using single mode fiber optics and a multiplexing approach. Unlike previously reported PS-OCT multiplexing schemes, the method uses a passive polarization delay unit and does not require active polarization modulating devices. This advance decreases system cost and avoids complex synchronization requirements. The polarization delay unit was implemented in the sample beam path in order to simultaneously illuminate the sample with two different polarization states. The orthogonal polarization components for the depth-multiplexed signals from the two input states were detected using dual balanced detection. PS-OCT images were computed using Jones calculus. 3D PS-OCT imaging was performed in the human and rat retina. In addition to standard OCT images, PS-OCT images were generated using contrast form birefringence and depolarization. Enhanced tissue discrimination as well as quantitative measurements of sample properties was demonstrated using the additional contrast and information contained in the PS-OCT images.

A Tunable Delay Line for Fast Analog Pulses as Key Element of a New Sum-Trigger for Cherenkov Telescopes

In 2007 a prototype of an analog Sum-Trigger for air Cherenkov telescopes was installed in the MAGIC I telescope lowering the trigger threshold from 55 GeV to 25 GeV and led to the detection of pulsed gamma-radiation from the Crab pulsar. However, that first prototype requires intensive maintenance and manual adjustment of each trigger channel and thus strongly limits its applicability for new high-resolution cameras comprising a larger number of pixels in the trigger area. Hence, a new setup with fully automatic setting of the trigger parameters has recently been designed. To minimize system costs and complexity, the improved version utilizes a sequential rate counting procedure to determine and compensate the gain and delay shifts of all channels caused by aging and changing operation conditions of the camera's photomultipliers (PMTs). The key element of the new system is a continuously tunable, passive delay line for fast analog signals enabling precise equalization of the PMT's signal transit times. When only a few small signals form the trigger, as in low energy air showers, precise temporal overlap in the analog sum is particularly essential for efficient detection. Unlike current commercial devices with bandwidths below 200 MHz and discrete delay setting, this new delay line allows smooth variation of each channel's delay within a range of 6 ns while maintaining a bandwidth of above 300 MHz, thus preserving the system's minimal pulse width of 2.6 ns. In 2010 a fully working new Sum-Trigger test setup comprising eight pixels has been built and temporarily installed at the MAGIC I telescope. It has been shown that the new design meets or even surpasses the requirements of a new analog trigger system with an anticipated energy threshold below 25 GeV.

A Novel Fiber-Based Variable All-Optical Packet Buffer Based on Self-Phase-Modulation-Induced Spectral Broadening

We propose a novel optical delay control mechanism to realize variable all-optical packet buffering, in which the amount of optical delay is controlled by the input signal power level. It consists of a passive fiber delay loop followed by an optical power dependent filter, which is realized by means of two stages of self-phase-modulation-induced spectral broadening and offset filtering. The feasibility of the proposed optical packet buffer has been investigated through numerical simulations and experiments. No polarization control and additional laser source are needed.

130 nm CMOS 공통 게이트 증폭기를 이용한 60 GHz 양방향 능동 위상변화기

본 논문에서는 기존 CMOS 수동 스위치를 사용한 switched - line 타입 위상변화기의 수동 스위치를 공통게이트 증폭기(양방향 증폭기)로 대체한 60 GHz CMOS 양방향 능동 위상변화기를 제안한다. 양방향 능동 위상변화기는 양방향 증폭기 블록과 수동 delay line 네트워크 블록으로 구성된다. 양방향 증폭기 블록은 순방향과 역방향의 특성이 같도록 설계하기 위해 공통 게이트 증폭기(CGA) 구조가 적합하며, 입력단과 출력단의 매칭은 대칭으로 이루어진다. 또한, 통합 바이어스 회로를 이용하여 1개의 바이어스 전압(<TEX>$V_{DS}$</TEX>)만으로도 증폭의 방향(순방향, 역방향)과 크기를 조절할 수 있도록 구성하였다. 수동 delay line 네트워크 블록은 마이크로스트립 라인으로 구성하였다. 동부 하이텍 1P8M 130-nm CMOS 공정을 이용하여 90도, 180도 1-bit 양방향 능동 위상변화기를 각각 설계하였고, 시뮬레이션 결과 60 GHz에서 평균 -3 dB의 삽입 손실을 얻었으며, 각각 90도 180도의 위상차를 얻었다. In this paper, a 60 GHz bidirectional active phase shifter with 130 nm CMOS is presented by replacing CMOS passive switchs in switched-line type phase shifter with Common Gate Amplifier(bidirectional amplifier). Bidirectional active phase shifter is composed of bidirectional amplifier blocks and passive delay line network blocks. The suitable topology of bidirectional amplifier block is CGA(Common Gate Amplifier) topology and matching circuits of input and output are symmetrical due to design same characteristic of it's forward and reverse way. The direction(forward and reverse way) and amplitude of amplification can be controlled by only one bias voltage(<TEX>$V_{DS}$</TEX>) using combination bias circuit. And passive delay line network blocks are composed of microstrip line. An 1-bit phase shifter is fabricated by Dongbu HiTek 1P8M 130-nm CMOS technology and simulation results present -3 dB average insertion loss and respectively 90 degree and 180 degree phase shift at 60 GHz.

Sub-milliwatt spectroscopic personal radiation device based on a silicon photomultiplier

A novel spectroscopic personal radiation device (SPRD) with sub-milliwatt power consumption is proposed. The SPRD is based on a compact, low-power, high-gain silicon photomultiplier (SiPM) coupled to a high-light-yield CsI(Tl) scintillator. The SiPM is operated in a special mode, in which its output is voltage rather than charge. In this mode, the SiPM output becomes higher and rises more slowly than in the charge amplification mode. Such a mode allows us to use a lower-frequency frontend amplifier with a lower gain and lower power consumption. Moreover, the very beginning of the slower, large-amplitude pulses is easier to detect with a comparator. At each detection event, the rest of the SPRD circuitry is activated only for the time needed for the pulse-processing. Because at background the radiation count rate is very low, some tens per second, and the duration of the signal-processing is very short, about 10 ms, the power-demanding SPRD circuitry is not activated most of the time, and its average power consumption is very low. Proper matching of the scintillator and the SiPM helps us to achieve the required gain from the radiation sensor with a relatively low-power, low-gain front-end amplifier. Optimizing the input impedance of the front-end amplifier helps us to obtain the required SiPM output amplitude and shape. Because it takes some time for the signal processing circuit to be activated, an additional passive delay and shaping circuit is used. An experimental model of this device is built, and tested. It is superior to other devices due to its very low power consumption, its portability, and its non-sensitivity to microphonics. The power consumption of the SPRD is about 0.3 mW by the radiation sensor and about 0.3 mW by the electronics (for a total of 0.6 mW as compared to above 20 mW consumed by conventional spectroscopic radiation devices). The power consumption has been measured at count rates up to a few hundreds per second, which are much higher than expected in practice.

OSCAT: Novel Technique for Time-Resolved Experiments Without Moveable Optical Delay Lines

Here, we present a novel technique for time resolved experiments without any moveable external delay line. Optical Sampling by Cavity Tuning (OSCAT) method is based on a femtosecond laser with a tunable repetition rate and a passive delay line. The time delay between the pump and probe pulses is determined by the repetition rate of the femtosecond laser.

Simplified Delay Extraction-Based Passive Transmission Line Macromodeling Algorithm

With higher operating frequencies, signal integrity and interconnect analysis in high-speed designs is becoming increasingly important. Recently, a passive delay extraction-based macromodeling algorithm (DEPACT) has been presented for simulation of long lossy coupled lines. In this paper, a new macromodeling algorithm based on DEPACT is introduced to handle several practical cases of importance, resulting in a simple and compact implementation in SPICE-like circuit simulators. The accuracy and efficiency of the proposed algorithm are validated using several practical examples.

Design and Analysis of a Transversal Filter RFIC in SiGe Technology

Filters are a critical component of every high-speed data communications system. Die area, power consumption, and RFIC integration are primary concerns for filter designers. The authors of this article have designed and fabricated a low-power analog filter with greatly reduced die area compared to passive delay lines. This transversal filter design has been realized in 47-GHz SiGe process technology.

Reconfigurable Delay Time Polymer Planar Lightwave Circuit for an X-band Phased-Array Antenna Demonstration

A 4-bit polymer optoelectronic true-time delay (TTD) device is demonstrated. The planar lightwave circuit (PLC) is composed of monolithically integrated low-loss passive polymer waveguide delay lines and five cascaded 2 times 2 polymer thermooptic switches. Waveguide junction offsets and air trenches simultaneously reduce the bending loss and device area. Simulations are used to optimize the trench and offset structures for fabrication. The 16 time delays generated by the device are measured to be in the range from 0 to 177 ps in 11.8-ps increments. The packaged PLC has an insertion loss of up to 14.9 dB, and the delay switching speed is 2 ms. An eight-element X-band phased-array antenna system is constructed to demonstrate the beam-steering capabilities of the 4-bit-delay devices. The TTD devices are shown to steer the far-field radiation pattern between 0deg and -14.5deg

Storage space saving and error avoidance of passive delay variation measurement employing a hash‐based technique for IP networks

AbstractDelay variation of packets is a significant performance measure in IP networks. Both active and passive measurements can evaluate delay variation. Among these, passive measurement is more advantageous because it can monitor the performance experienced by users without disturbing network load. Meanwhile, a shortcoming of using passive measurement is an extremely large storage space required to record packets and timestamps. This problem is solved by feeding a portion of each packet to a hash function as its input and recording the output to identify the packet. Since the data length of the hash function output is very short, such an approach effectively decreases the storage space. However, this approach still needs a considerably large storage space to record time‐stamps. Additionally, the collisions among hash output values may bring unacceptable measurement errors. This paper proposes a method to decrease the storage space required to record timestamps for hash‐based delay variation measurement. This decrease is achieved by a variable length coding of timestamps. The paper also presents methods to avoid measurement errors brought by hash value collisions. Through experiments, it is shown that the proposed techniques correctly measure delay variation as well as effectively reduce the storage space. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(3): 21–32, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20328

Prediction of Time to Shivering in Resting Subjects during Mild Cold Transients

The initial response to cold stress consists of vasoconstriction (VC) to conserve metabolic heat, followed by shivering thermogenesis when heat conservation is no longer sufficient to maintain core temperature (Tc). However, the individual characteristics that influence heat conservation mechanisms are unclear. PURPOSE: To determine individual characteristics that influence heat conservation and time to shivering. METHODS: 85 subjects (43 men, 42 women) of varying age (18–89 years), body mass (46–104 kg), adiposity (10–43 %fat), and lean limb muscle mass (DXA; 5.0–9.5 kg-m2) sat at rest during a cooling transient protocol in which dry bulb temperature was progressively decreased. The protocol was terminated at the onset of visible shivering. Esophageal and skin temperatures and red blood cell flux (laser-Doppler flowmetry) were measured continuously, and O2 consumption and CO2 production were measured every 10 min. Cutaneous vascular conductance (CVC) was calculated and expressed as a percent of baseline (=flux/MAR CVC%base). Tissue insulation (It), heat debt and metabolic heat production were calculated using standard equations. Stepwise regression analysis was conducted to determine the individual characteristics predictive of time to shivering. RESULTS: Limb muscle mass and CVC%base were significant predictors of time to shivering (r2=.29, p < 0.001). The addition of the change in Itfrom baseline (AI) improved the prediction equation (r2=.37, p < 0.001). Adiposity, expressed as either % fat, limb fat mass relative to height or body fat mass relative to height, did not improve prediction. The final prediction equation was: time to shiver = 85.9 + 2.99*limb muscle mass-0.51*CVC%base + 275*δIt. Age was not a significant predictor of time to shivering threshold, but was correlated with CVC%base (r2=.41, p < 0.001). CONCLUSIONS: The combination of a high limb muscle mass and effective skin VC (but not adiposity) predicts effective passive heat conservation and delay of the need to increase heat production via shivering. Supported by NIH Grant R01 AG07004-15 and NIA Grant T32-AG00048.

0.18-/spl mu/m CMOS equalization techniques for 10-Gb/s fiber optical communication links

Limitations in data transmission caused by modal dispersion in fiber-optic links can be significantly improved using equalization techniques. In this paper, two different equalizer implementation approaches are proposed to extend the transmission capacities of existing fiber-optic links. The building blocks of the equalizer including a multiplier cell, a delay line, and an output buffer stage are fully integrated on a 0.18-/spl mu/m CMOS process. For the continuous-time tap-delay implementation, a passive LC delay line and an active inductance peaking delay line are compared for performance against process variation, as well as power consumption. In addition, a delay-locked loop is proposed to counter delay variations caused by changes in the process corner. A 10-Gb/s nonreturn-to-zero signal is received after transmission through a 500-m multimode-fiber channel, and the signal impairment due to the differential modal delay is successfully compensated using both feed-forward equalizers.

Microchannel plate position read-out system using field programmable gate arrays

This article describes a technique that was developed to register particle events from a microchannel plate (MCP) used as the position sensitive detector within an electron spectrograph instrument. The MCP/amplification section is composed of 2 Z-stack MCP modules, an anode pattern connected to a passive delay line, and associated amplification circuitry. The digital output pulses from the amplification circuit are fed into a decoding architecture composed of delay chains integrated inside a field programmable gate array. Test results of the read-out system with delay line simulated input signals, have shown a good response with less than 1 error per 108 particle incident events. Initial tests with a MCP delay line anode have verified this technique and can be used to detect electron positions.

Tunable microwave photonic passive delay line based on multichannel fibre grating matrix

A discretely tunable passive microwave photonic delay line based on a multichannel grating matrix is demonstrated. This topology demonstrates high-speed high-resolution time delaying of microwave signals, along with requiring a reduced number of discrete gratings for any given delay range. High channel isolation and low insertion loss are also features of this topology, making this suitable for many wideband applications.

A Plane-Wave Beam-Steering Lens Design Using Microstrip Switched-Line Phase Shifters

A compact beam-steering lens design appropriate for millimeter-wave and submillimeter-wave applications is experimentally verified with an X-band test model. The lens achieves coupling to plane-wave beams through arrays of patch antennas placed on its two outer surfaces. The isolation between input and output antennas is accomplished by inserting a metal ground plane in the middle of the lens. The two closest patch antennas on the front and the backside are connected together with microstrip circuits that include switched-line phased shifters and interconnecting vias through the lens substrate. Three different X-band 100-element plane-wave microstrip lenses that use passive delay lines instead of actual phase-shifters were fabricated to successfully demonstrate the beam-steering angles of 20 and 40 degrees. From a separate waveguide measurement on the unit-cell element only, the insertion loss of the lens was estimated to be approximately 3.5 dB with bandwidth of 2% at 10 GHz.

A subharmonically injected LC delay line oscillator for 17-GHz quadrature LO generation

An injection-locked delay line oscillator multiplies a 5-6-GHz input by 3 to generate I/Q LO signals for 17-GHz wireless networking applications. I/Q errors caused by asymmetric injection are minimized by symmetric injection via a passive polyphase prefilter. Passive delay lines set the measured free-running frequency of the LC ring oscillator to 16.24 GHz. The measured locking range for a 0 dBm (50 /spl Omega/) input is 14.6-17.86 GHz. Input-to-output phase noise degradation is negligible, and I/Q amplitude and phase errors are <0.17 dB and <2/spl deg/, respectively. Power consumption of the 1.2/spl times/1.4 mm/sup 2/ 0.2 /spl mu/m SiGe BiCMOS testchip (excluding buffers) is 22 mW at 2.2 V.