1,953 research outputs found
Analysis and equalization of data-dependent jitter
Data-dependent jitter limits the bit-error rate (BER) performance of broadband communication systems and aggravates synchronization in phase- and delay-locked loops used for data recovery. A method for calculating the data-dependent jitter in broadband systems from the pulse response is discussed. The impact of jitter on conventional clock and data recovery circuits is studied in the time and frequency domain. The deterministic nature of data-dependent jitter suggests equalization techniques suitable for high-speed circuits. Two equalizer circuit implementations are presented. The first is a SiGe clock and data recovery circuit modified to incorporate a deterministic jitter equalizer. This circuit demonstrates the reduction of jitter in the recovered clock. The second circuit is a MOS implementation of a jitter equalizer with independent control of the rising and falling edge timing. This equalizer demonstrates improvement of the timing margins that achieve 10/sup -12/ BER from 30 to 52 ps at 10 Gb/s
Wideband phase-locked angular modulator
A phase-locked loop (PLL) angular modulator scheme has been proposed which has the characteristics of wideband modulation frequency response. The modulator design is independent of the PLL closed-loop transfer function H(s), thereby allowing independent optimization of the loop's parameters as well as the modulator's parameters. A phase modulator implementing the proposed scheme was built to phase modulate a low-noise phase-locked signal source at the output frequency of 2290 MHz. The measurement results validated the analysis by demonstrating that the resulting baseband modulation bandwidth exceeded that of the phase-locked loop by over an order of magnitude. However, it is expected to be able to achieve much wider response still
An Offset Cancelation Technique for Latch Type Sense Amplifiers
An offset compensation technique for a latch type sense amplifier is proposed in this paper. The proposed scheme is based on the recalibration of the charging/discharging current of the critical nodes which are affected by the device mismatches. The circuit has been designed in a 65 nm CMOS technology with 1.2 V core transistors. The auto-calibration procedure is fully digital. Simulation results are given verifying the operation for sampling a 5 Gb/s signal dissipating only 360 uW
Long-term Stabilization of Fiber Laser Using Phase-locking Technique with Ultra-low Phase Noise and Phase Drift
We review the conventional phase-locking technique in the long-term
stabilization of the mode-locked fiber laser and investigate the phase noise
limitation of the conventional technique. To break the limitation, we propose
an improved phase-locking technique with an optic-microwave phase detector in
achieving the ultra-low phase noise and phase drift. The mechanism and the
theoretical model of the novel phase-locking technique are also discussed. The
long-term stabilization experiments demonstrate that the improved technique can
achieve the long-term stabilization for the MLFL with ultra-low phase noise and
phase drift. The excellent locking performance of the improved phase-locking
technique implies that this technique can be used to stabilize the mode-locked
fiber laser with the highly stable H-master or optical clock without stability
loss
Stray Magnetic Field Compensation with a Scalar Atomic Magnetometer
We describe a system for the compensation of time-dependent stray magnetic
fields using a dual channel scalar magnetometer based on non-linear Faraday
rotation in synchronously optically pumped Cs vapour. We detail the active
control strategy, with an emphasis on the electronic circuitry, based on a
simple phase-locked-loop integrated circuit. The performance and limits of the
system developed are tested and discussed. The system was applied to
significantly improve the detection of free induction decay signals from
protons of remotely magnetized water precessing in an ultra-low magnetic field.Comment: 8 pages, 6 figures, 31 refs, v2 (with minor improvements) appearing
in Rev.Sc.Instr. June 201
MS
thesisCircuitry utilizing integrated circuits has been designed as peripheral equipment to a cassette recorder for inexpensive take-home cardiac monitoring. The circuitry is for frequency modulation for recording and demodulation upon playback of three synchronous multiplexed analog signals: the ECG signal, a reference signal which after demodulation is subtracted from the ECG signal to compensate for variable tape speed, and an episode signal actuated by the patient during ECG recording to indicate a particularly noticeable episode. The original goals were to keep the total component cost under 60.00. An expensive item is the cassette recorder which has considerable variations in price (100.00). The circuitry described in this thesis has been designed to work with the Concord Model F-26 cassette recorder and other cassette recorders of similar quality. The quality (signal to noise ratio) of the ECG reproduction, although acceptable, could probably have been improved were in not for the degradation of the phase lock loop FM demodulator with an input of multiplexed signal, which reduced the lock range; and therefore required a reduction of the gain of the ECG amplifier. The design goal of the project was achieved since the recorder and components can be purchased for less than $100.00 (in single quantities) and the system provided acceptable ECG's for clinical use. The knowledge and experience gained for this thesis project has been of considerable value. Hopefully this work will lead to further experiments, improvements, and other applications of physiological monitoring with an inexpensive cassette recording system
Sub-100-as timing jitter optical pulse trains from mode-locked Er-fiber lasers
We demonstrate sub-100-attosecond timing jitter optical pulse trains
generated from free-running, 77.6-MHz repetition-rate, mode-locked Er-fiber
lasers. At -0.002(\pm0.001) ps2 net cavity dispersion, the rms timing jitter is
70 as (224 as) integrated from 10 kHz (1 kHz) to 38.8 MHz offset frequency,
when measured by a 24-as-resolution balanced optical cross-correlator. To our
knowledge, this result corresponds to the lowest rms timing jitter measured
from any mode-locked fiber lasers so far. The measured result also agrees
fairly well with the Namiki-Haus analytic model of quantum-limited timing
jitter in stretched-pulse fiber lasers.Comment: 4 pages, 2 figures, to appear in Optics Letter
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