Phase Detection Scheme Research Articles

A 1-16-Gb/s All-Digital Clock and Data Recovery With a Wideband, High-Linearity Phase Interpolator

An all-digital phase interpolator (PI)-based clock and data recovery (CDR) is proposed in this paper to accommodate any data rate continuously from 1 to 16 Gb/s with quadrature sampling clocks from 4 to 8 GHz. A new low-power two-step PI (TSPI) with high linearity over 4–8 GHz range is presented. The all-digital CDR control loop adopts a multimode phase detection scheme enabling continuous data rate support. The digital architecture not only eliminates the large filtering capacitor but also makes the design more tolerant to process, voltage, and temperature variations. The CDR core occupies 0.088 mm2 in a commercial 65-nm CMOS technology and consumes 73.1 mA at 16 Gb/s from a 1.2 V power supply. The differential nonlinearity of the PI is measured to be within 0.48 LSB. The measurement results show that this CDR can function at the proposed phase detection modes and is able to exceed the synchronous optical networking (SONET) OC-192 jitter tolerance mask at least by 0.2 unit interval at high frequencies (4–100 MHz) with a $2^{31}-1$ pseudorandom binary sequence data pattern at 10 Gb/s and a target bit error rate of $10^{-12}$ .

A Simultaneous Diagnosis Method for Power Switch and Current Sensor Faults in Grid-Connected Three-Level NPC Inverters

A simultaneous diagnosis method for power switch open-circuit faults and current sensor faults of grid-connected three-level neutral point clamped (NPC) inverters is proposed herein. First, by designing the adaptive reaching law and reducing the steady-state resonance, a novel interval sliding model observer is developed to track and estimate the three-phase currents accurately and rapidly. Next, a faulty phase detection scheme using an adaptive threshold is proposed to achieve sensitive and robust detection results. Also, the measured three-phase currents sum and estimated three-phase currents sum are used to distinguish power switch open-circuit faults and current sensor faults. Subsequently, a faulty switch location method and the current sensor fault type identification method are proposed, using some of the same identification variables. Finally, combining the faulty phase detection variables with the identification methods ensures the feasibility of the detection and identification of 12 open-circuit faults and 9 current sensor faults. The hardware-in-the-loop test results are performed to validate the effectiveness and robustness of the proposed method.

A 1.2 V 0.4 mW 20~200 MHz DLL Based on Phase Detector Measuring the Delay of VCDL

A delay locked loop (DLL) based on a Phase Detector, which Measures the Delay of the Voltage-controlled delay line (PD-MDV), which is tVCDL, with efficient and stable locking performance was proposed. In contrast to conventional phase detectors, the PD-MDV measures tVCDL more accurately; thus, it can always generate the correct up/down (UP/DN) pulses. The proposed technique prevents becoming stuck in the fastest operation, in which UP pulses continue to appear even when tVCDL < tREF, where tREF is the reference time, which is an input of the DLL. In the reverse case, the PD-MDV prohibits DN pulses from continuing to appear under the condition tVCDL > tREF, thereby freeing the DLL from harmonic locking and becoming stuck in the slowest operation. The proposed phase detection scheme was verified under various conditions, including process corners, temperature variations, and abrupt changes in tREF. The proposed 1.2 V, 20~200 MHz DLL with the PD-MDV was designed using the 65 nm process, with a power consumption of 0.4 mW at 200 MHz.

Simultaneous Phase Detection of Multi-Wavelength Interferometry Based on Frequency Division Multiplexing

Simultaneous phases detection in multi-wavelength interferometry (MWLI) is essential for high-accuracy dynamic absolute distance measurement in high-end equipment manufacturing. To address this problem, a simultaneous phase detection scheme based on frequency-division multiplexing (FDM) technique is proposed in this paper. High-frequency sinusoidal phase modulation with non-overlapping frequencies were applied to multiple lasers individually using electro-optic modulators (EOMs), and interference phases of multiple wavelengths were extracted in parallel using phase generated carrier (PGC) demodulation technique from the FDM interference signal. Principles of FDM multi-wavelength interferometry and simultaneous phase detection scheme were illustrated. A FDM dual-wavelength interferometer was constructed to verify the performance of the proposed phase detection scheme by simulation analysis and experiments. Results of simulations show that the resolution, accuracy and nonlinear error of the two demodulated phases are all better than 0.01°. Experiments of nanometer displacement measurement further verified the good performance of the phase detection scheme and its feasibility in dynamic measurement.

Power Based Open Phase Condition Detection Scheme

Open phase condition can occur in all types of power plants and substations, of which the detection and treatment measures are beginning to be required in the design standards of nuclear power plants. Operation experience shows that when open phase condition occurs on the primary side of the transformer, especially under light and no-load conditions, the traditional protection device based on sequence components cannot reliably operate, and the safety equipment that is used to isolate station auxiliaray transformer will not work properly, which leads to the failure of safe bus automatically transfered to a stanby power source. This situation posts great threats to the safe operation of nuclear power plants. This article systematically analyzes the difficulties in open-phase detection and the change in electrical quantities after open phase fault, and more importantly, focuses on the analysis of the power characteristics after the fault, based on which a new open phase detection scheme for nuclear power plants is proposed. It can also be applied to other types of power plants. The method and its feasibility are verified on PSCAD simulation software. The paper provides a new idea for the detection of open phase fault.

Computational Oblique Illumination Microscopy With Isotropic High Resolution

Although various advanced super-resolution microscopies have been developed, conventional microscopes are still the most widely used. Therefore, it is still one of the goals of light microscopists to improve the imaging performance of conventional microscopes. Ernst Abbe had proven the resolution of a bright-field microscope can be improved by oblique illumination in 1873, but the approach has not been widely applied in practice due to the intrinsic drawback that the lateral resolution of the image is anisotropic. In this article, computational oblique illumination microscopy (COIM) is proposed to isotropically improve lateral resolution. Benefiting from outstanding performance of light emitting diodes (LEDs), the programmable symmetrical oblique illumination by LEDs can easily be implemented. COIM uses symmetrical oblique illuminations to enhance the absorption contrast and weaken the phase contrast in images; then an iterative algorithm is used to fuse an image with the isotropic high lateral resolution. Unlike synthetic aperture imaging, COIM does not require phase involvement, so there are no troublesome phase detection schemes. The experimental results indicate that COIM can resolve Element 6 in Group 11 (bar or space width 137 nm) of a USAF test target using a high numerical aperture (NA) objective lens (NA = 1.25) and oblique-illumination sources (center wavelength 520 nm). The proposed technique provides a new way to improve the resolution of bright-field microscope.

Residual current-based method for open phase detection in radial and multi-source power systems

Open phase conditions typically result in very low fault currents which makes their detection using the existing conventional protective relaying schemes very difficult. This paper proposes a new current-only Open Phase Detection (OPD) scheme suitable for effectively grounded distribution networks. The proposed OPD approach is based on the prevailing current imbalance in the network. Reference phase currents are calculated (predicted) online using Residual Current Multiplying Factors (RCMFs), and are afterwards compared with the measured phase currents. A mismatch between the predicted reference phase currents and the measured phase currents is used as an indication of an open conductor event.Extensive studies were performed using a distribution network modelled in RSCAD software. The performance of the proposed protection scheme was validated using the Real-Time Digital Simulator (RTDS) for various open phase events and non-open phase conditions. The experimental results obtained validate the effectiveness of the proposed OPD scheme.

Phase Measurement of Optical Fiber via Weak-Value Amplification

A precision phase detection scheme employing a weak-value amplification (WVA) technique is proposed and demonstrated. With a minimum detectable phase change of $\sim \!10^{-5}$ rad, the present system rivals similar free-space schemes using bulk optical components only. The new setup is tested in a simple hydro-pressure detection experiment, with a short segment of fiber under water, showing a remarkable responsivity to small pressure changes.

Enhanced Frequency Stability Over Fiber Link With Improved Phase Discrimination Scheme

We demonstrate a phase-stability radio-frequency (RF) dissemination system via fiber link with direct phase discrimination. The phase fluctuation of the RF signal is identically transferred to a 10 MHz intermediate frequency (IF) by using dual-heterodyne phase error transfer. It guarantees that the phase discrimination of the IF signals and the atomic clock frequency signal can be directly performed without the frequency division or multiplication. This scheme can enhance the frequency stability of the dissemination system by mean of higher precision phase detection and high noise suppression capability. Experimentally, the residual phase noise of compensated system with improved phase detection scheme is -50 dBc/Hz and -67 dBc/Hz at 0.01 Hz and 1 Hz frequency offset, respectively, the RMS timing jitter in the frequency range from 0.01 Hz to 1 MHz reaches about 50 fs. Compared with the frequency division and multiplication methods, the frequency stability is improved nearly one orders of magnitude to 5 × 10 -17 at 2000 s averaging time.

Laser–RF synchronization based on digital phase detector

Laser oscillator synchronization with RF reference signal is ultra-important for a modern light source based on the accelerator. For Tsinghua Thomson scattering X-ray source, we have synchronized the mode-locked laser oscillator to RF reference signal with 48.2 fs RMS relative jitter. Both fundamental and harmonic signals derived from photo diode detection are used for laser–RF synchronization in our scheme. The fundamental signal is for coarse laser–RF synchronization and multiple laser oscillator synchronization. The harmonic signal is for high precise phase locking. The digital phase detector is implemented in the synchronization scheme for less noise, replacing the mixing to DC phase detection scheme. The digital processing algorithm for synchronization is commonly used in low-level RF control field. In order to test the phase locking loop logic without damaging the real laser oscillator, a laser oscillator emulator was developed for phase locking. This paper will report the laser–RF synchronization scheme and its performance. The laser oscillator emulator system will also be introduced here.

Absolute distance measurement by dual-comb interferometry with multi-channel digital lock-in phase detection

We present a dual-comb-based heterodyne multi-wavelength absolute interferometer capable of long distance measurements. The phase information of the various comb modes is extracted in parallel by a multi-channel digital lock-in phase detection scheme. Several synthetic wavelengths of the same order are constructed and the corresponding phases are averaged to deduce the absolute lengths with significantly reduced uncertainty. Comparison experiments with an incremental HeNe reference interferometer show a combined relative measurement uncertainty of 5.3 × 10−7 at a measurement distance of 20 m. Combining the advantage of synthetic wavelength interferometry and dual-comb interferometry, our compact and simple approach provides sufficient precision for many industrial applications.

Hysteresis assisted narrowband resonances in a chain of nonlinear plasmonic arrays

The plasmonic structures exhibiting narrowband resonances (NBR) are of a great interest for various applications. We propose to use hysteresis behavior in a 1D system of nonlinear nanoresonators in order to achieve the NRB; the nonlinearity is provided by saturation of a two-level quantum system coupled with the nanoresonators (nanolaser/spaser configuration). Quantum Dots (QD) were assumed as quantum systems; their numerical parameters have been adopted for estimations. Role of the loss compensation on the quality of the NBR is shown for below (under compensation) and above threshold (generating spasers) operation modes. Amplitude and phase detection schemes of the prospective experimental realization are compared using the developed model. Possible sensor oriented applications of the proposed system are discussed.

A 40 Gb/s Serial Link Transceiver in 28 nm CMOS Technology

A 40 Gb/s serial link interface is presented that includes four lanes of transceiver optimized for chip-to-chip communication while compensating for 20 dB of channel loss. Transmit equalization consists of a 2-tap feed-forward equalizer (FFE) while receive equalization includes a 2-tap FFE using a transversal filter, a 3-stage continuous-time linear equalizer with active feedback, and discrete-time equalizers consisting of a 17-tap decision feedback equalizer (DFE) and a 3-tap sampled FFE. The receiver uses quarter-rate double integrate-and-hold sampling. The clock and data recovery (CDR) unit uses a split-path CDR/DFE design which facilitates wider bandwidth and lower jitter simultaneously. A phase detection scheme that filters out edges affected by residual inter-symbol interference allows recovering a low-jitter clock from a partially-equalized eye. A fractional-N PLL is implemented for frequency offset tracking. Combining these techniques, the digital CDR recovers a stable 10 GHz clock from an eye containing 0.8 UI p-p input jitter and achieves 1-10 MHz of tracking bandwidth. The transceiver achieves horizontal and vertical eye openings of 0.27 UI and 120 mV, respectively, at BER = 10 -9 . The quad SerDes is realized in 28 nm CMOS technology. Amortizing common blocks, it occupies 0.81 mm $^{2}$ per lane and achieves 23.2 mW/Gb/s power efficiency at 40 Gb/s.

Design and Simulation of Quadrature Phase Detection in Electrical Capacitance Volume Tomography

Capacitance measurement accuracy is affected by phase conformity between signal and reference. This work describes phase detection scheme which is necessary for phase synchronization in tomography application. Core processing for calculating phase and amplitude of the detected signal was built on FPGA (Field-Programmable Gate-Array) platform. Phase shift demodulation algorithm employs IP core provided by Xilinx FPGA. Direct digital synthesizer (DDS), multiplier, accumulator, and CORDIC (coordinate rotation digital computer) modules were used as excitation-reference signal generator, signal multiplication, accumulation, and conversion to polar coordinate in order to conduct trigonometric operation respectively. Hardware design was emulated on MATLAB-Xilinx System Generator to observe its performance. Phase detection range 0-114.58 o and mean absolute error 0.58 o have been achieved. Data processing rate solely at digital signal stage was approximately 100data/s suitable for 32-channel electrical capacitance volume tomography (ECVT) system.

최소 샘플링의 고속푸리에 변환을 이용한 비정상 계통의 향상된 위상추종 및 고조파 검출 기법

최소 샘플링의 고속푸리에 변환을 이용한 비정상 계통의 향상된 위상추종 및 고조파 검출 기법

A 4–32 Gb/s Bidirectional Link With 3-Tap FFE/6-Tap DFE and Collaborative CDR in 22 nm CMOS

This paper details the design of an 8-lane bidirectional link for both within-the-box and external communications in 22 nm CMOS technology. A low profile connector with a high density cable assembly ensure a data rate of up to 32 Gb/s per lane while maintaining channel loss below 25 dB. Channel equalization is performed by a combination of a 3-tap feed-forward equalizer (FFE), single-stage continuous-time linear equalizer (CTLE) and a 6-tap decision-feedback equalizer (DFE). Collaborative timing recovery is used to enable lane characterization without degrading jitter performance. Phase error decimation, with a conditional phase detection scheme, is used to reduce the DFE complexity by 50%. Power consumption over a wide range of data rates from 4 to 32 Gb/s is reduced by using regulated CMOS clocking with lane bundling, low swing transmitter with a source-series terminated (SST) driver and a highly reconfigurable receiver with an active inductor CTLE. At a lane data rate of 32 Gb/s, over a 0.5 m cable with 16 dB of loss, a transceiver lane consumes 205 mW from a 1.07 V supply. The power scales down to 26 mW from a 0.72 V supply at 8 Gb/s, when transmitting over a channel with 8 dB loss. The active silicon area per lane is 0.079 mm 2 .

Design of a real-time two-color interferometer for MAST Upgrade.

A single chord two-color CO2/HeNe (10.6/0.633 μm) heterodyne laser interferometer has been designed to measure the line integral electron density along the mid-plane of the MAST Upgrade tokamak, with a typical error of 1 × 10(18) m(-3) (∼2° phase error) at 4 MHz temporal resolution. To ensure this diagnostic system can be restored from any failures without stopping MAST Upgrade operations, it has been located outside of the machine area. The final design and initial testing of this system, including details of the optics, vibration isolation, and a novel phase detection scheme are discussed in this paper.

Development of phase detection schemes based on surface plasmon resonance using interferometry.

Surface plasmon resonance (SPR) is a novel optical sensing technique with a unique ability to monitor molecular binding in real-time for biological and chemical sensor applications. Interferometry is an excellent tool for accurate measurement of SPR changes, the measurement and comparison is made for the sensitivity, dynamic range and resolution of the different analytes using interferometry techniques. SPR interferometry can also employ phase detection in addition to the amplitude of the reflected light wave, and the phase changes more rapidly compared with other approaches, i.e., intensity, angle and wavelength. Therefore, the SPR phase interferometer offers the advantages of spatial phase resolution and high sensitivity. This work discusses the advancements in interferometric SPR methods to measure the phase shifts due to refractive index changes. The main application areas of SPR sensors are demonstrated, i.e., the Fabry-Perot interferometer, Michelson interferometer and Mach-Zehnder interferometer, with different configurations. The three interferometers are discussed in detail, and solutions are suggested to enhance the performance parameters that will aid in future biological and chemical sensors.

New Multilevel Bang-Bang Phase Detector

Equivalent time oscilloscopes are widely used as an alternative to real-time oscilloscopes when high timing resolution is needed. For their correct operation, they need the trigger signal to be accurately aligned to the incoming data, which is achieved by the use of a clock and data recovery circuit (CDR). In this paper, a new multilevel bang-bang phase detector (BBPD) for CDRs is presented; the proposed phase detection scheme disregards samples taken close to the data transitions for the calculation of the phase difference between the inputs, thus eliminating metastability, one of the main issues hindering the performance of BBPDs.

Communication: Two-dimensional gas-phase coherent anti-Stokes Raman spectroscopy (2D-CARS): Simultaneous planar imaging and multiplex spectroscopy in a single laser shot

Coherent anti-Stokes Raman spectroscopy (CARS) has been widely used as a powerful tool for chemical sensing, molecular dynamics measurements, and rovibrational spectroscopy since its development over 30 years ago, finding use in fields of study as diverse as combustion diagnostics, cell biology, plasma physics, and the standoff detection of explosives. The capability for acquiring resolved CARS spectra in multiple spatial dimensions within a single laser shot has been a long-standing goal for the study of dynamical processes, but has proven elusive because of both phase-matching and detection considerations. Here, by combining new phase matching and detection schemes with the high efficiency of femtosecond excitation of Raman coherences, we introduce a technique for single-shot two-dimensional (2D) spatial measurements of gas phase CARS spectra. We demonstrate a spectrometer enabling both 2D plane imaging and spectroscopy simultaneously, and present the instantaneous measurement of 15,000 spatially correlated rotational CARS spectra in N2 and air over a 2D field of 40 mm(2).