We have studied wideband dispersion-free slow light in photonic crystal waveguides and other photonic nanostructures, which allows tunable delays in short optical pulses and the enhancement of light-matter interaction. This paper demonstrates the state-of-the-art devices fabricated by CMOS-compatible process, where compact devices of 200-400µm lengths are integrated with Si photonics components and controlled by DC and AC electronics. They are applied for dispersion controllers, optical correlators, DQPSK receivers, retiming of pulse train, two-photon absorption photo-diodes and Mach-Zehnder modulators.
In this paper, an improved hysteretic PWM control with feed-forward and feedback for the buck converter is presented. The proposed control method is based on hysteretic control of capacitor C voltage, which not only offers faster transient response to meet the challenges of the power supply requirements of fast dynamic input and load changes, but also provides better stability and solves the compensation problem of the error amplifier in the conversional voltage PWM control. Finally, the steady-state operation of the control method is analyzed and verified by the simulation and experimental results.
A PFC boost converter is a non-linear system whose small perturbation model is changed at each operating point depending on a duty ratio. The robust controller for the PFC boost converter is needed to suppress the output voltage change at load sudden change while attaining high power factor and low harmonic. In this paper, the combining method and design methods of twoapproximate 2-degree-of-freedom (A2DOF) controllers which simplify the overall controller and attain good robustness are proposed. The proposed controller is actually implemented on a Micro-processor and is connected to the PFC boost converter. Experimental studies demonstrate that the proposed robust controller is effective to suppress the output voltage change to improve power factor and to decrease harmonic.
Optimal binary codes for pixel values are designed for accurate block matching in the fast motion estimation. The conventional binary block matching techniques reduce the computational complexity and the memory bandwidth for the motion estimation, but they degrade the matching accuracy. We find the optimal mapping function between the set of decimal numbers for uniformly quantized pixel values and the set of binary codes, so that the weighted sum of mean squared errors between the absolute differences and the Hamming distances is minimized. Experimental results show that the proposed three-bit binary code set yields about 0.4dB gain over the conventional techniques.
A new frequency offset compensation technique for the MIPI Low Latency Interface (LLI) application is proposed. The proposed clock and data recovery (CDR) circuit has a composite structure of bang-bang and oversampling phase detectors with an offset estimator. Digitally estimated frequency offset is used to determine the gain of the 2nd order digital CDR. An elastic FIFO for the oversampled multi-phase data stream is not needed, because the proposed offset estimator can compensate for frequency offset instead. With a frequency offset ranging from −60,000ppm to +60,000ppm, the proposed CDR has a very fast and almost constant lock acquisition time of less than 15 unit intervals and a short recovery logic latency of 1 unit interval. The proposed digital CDR is implemented using 65-nm CMOS technology. It consumes 5.1mW from a 1.2-V power supply at 5.8Gb/s.
This letter presents a low power CMOS pulse generator based on spectral efficiently gated oscillator for multiband impulse radio ultra-wideband (UWB) system. The pulse generator is based on an on/off switched LC oscillator with the trapezoid switching pulse. By using trapezoid pulse for on/off switching signal of the oscillator, better output spectral characteristic can be achieved without additional pulse shaping filter due to the more symmetric triangular envelope of the output pulse. Output pulse spectrum shows more than 30dB of sideband rejection without additional filtering. The pulse generator dissipates only 10pJ per pulse from 1.2-V supply.