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We present the modeling of a laterally coupled twin-stripe laser for boosting the modulation bandwidth far beyond relaxation frequencies. The 3dB-modulation bandwidth is increased to be doubled thanks to optical feedback in laterally coupled cavities.
We present modeling of strong slow-light feedback in VCSEL coupled with a transverse cavity. We show boosting of the 3dB modulation bandwidth to frequencies reaching 70 GHz as well as resonance modulation around 90 GHz.
Frequency Modulated Continuous Wave (FMCW) radars have been widely used for short and medium range detection. Applications of FMCW radar, where measuring short distances is critical, need to have a high accuracy. In the FMCW radar systems, the received signal is a delayed version of the transmitted signal. The range is calculated by measuring the beat frequency of the received signal. The range resolution...
An FPGA based 2nd-order passive KD1S sigma-delta modulator was designed, simulated and tested. The design is implemented on an Altera Cyclone IV EP4CE115 FPGA. All active components such as digital logic, clock circuitry, and registers are located internally on the FPGA chip with only passive RC lumped analog components located off chip. The circuit uses eight logic elements and two PLL blocks on...
Main memory system is facing increasingly high pressure from the advances of multi-core processors. The simplicity of conventional memory architecture has helped minimize memory latency and reduce the design cost. However, in present multi-core era, it is increasingly attractive to adopt flexible and advanced memory organization to further improve memory bandwidth utilization, power efficiency, and...
A bandpass delta-sigma modulator with a widely tunable center frequency range for direct digitization of IF or RF signals can be a key building block for highly digitized radio receivers. The performance of the bandpass modulator is highly dependent on the accuracy of the noise transfer function zero locations in the presence of process spread. An automatic calibration method is proposed to calibrate...
High speed modulation characteristics are investigated for directional emission microdisk lasers. The increase of modulation speed with the decrease of the radius is observed, and improvement of 3dB bandwidth is demonstrated at optical injection locking.
in this paper, two different methods are introduced to radiate a wideband signal through an electrically small antenna. One method shifts the resonant frequency of the antenna and radiates a frequency modulated signal while the other presents a feeding mechanism to radiate an amplitude modulated signal. Both methods are categorized under antenna direct modulation and take advantage of transient properties...
In this study, we briefly introduce a novel concept of dual-band polar transmitter design based on digital quadrature modulation techniques for the application of railroad wireless communication (e.g., TRS & GSM-R) to reduce the bandwidth of dual-band PM (phase modulation) signal. We show that the complex signal processing at low frequency effectively utilizes the polar transmitter which is susceptible...
We demonstrate degenerate four-wave mixing of a 12×100 Gb/s DP-QPSK signal with counter-phase dithering by a phase modulator embedded in a fiber-loop. A ≈9 dB higher conversion efficiency enables an OSNR penalty of 0.7 dB at 10−3 BER.
A 10-GHz TO-can packaged colorless laser diode under coherent injection-locking for 42-Gbit/s 64-QAM OFDM transmission over 25-km SMF is demonstrated to achieve the lowest BER of 4.2×10−4 at a receiving power of −2 dBm.
We present in the paper results of a generalised micro-Doppler analysis that is suited to high range resolution radar. The target echo energy is here represented in the three dimensional space of time, Doppler, and additionally range, what can provide more information on target micro-motion than the standard micro-Doppler analysis which is performed in the time-Doppler plane. The analyzed signals...
This paper presents the design and implementation of a C-band Analog-Front-End (AFE) for Frequency Modulated Continuous Wave (FMCW) Radar. This AFE is based on commercial off-the-shelf (COTS) radio frequency components. The system was designed to be used in various radar applications, including short range mode, Synthetic Aperture Radar (SAR) and Inverse Synthetic Aperture Radar (ISAR). The AFE system...
A wide bandwidth VCO-based continuous-time ΔΣ modulator that uses combined phase and frequency feedback to mitigate VCO non-linearity and ease DEM timing requirement is presented. Fabricated in 65nm CMOS process, the prototype modulator operates at 1.2GS/s and achieves 71.5dB SNDR in 50MHz bandwidth while consuming 54mW of power, which translates to an FoM of 176fJ/conv-step.
This paper presents the design and simulation of a time-interleaved delta-sigma modulator as part of a digital transmitter chain. The architecture is chosen based on a critical path analysis in order to reach very high frequency operation. The modulator's configurability allows it to target signal bandwidths from 20 MHz up to 160 MHz with a SNR greater than 67 dB. Finally, the modulator is synthesized...
In this paper, we study the notion of codes with hierarchical locality that is identified as another approach to local recovery from multiple erasures. The well-known class of codes with locality is said to possess hierarchical locality with a single level. In a code with two-level hierarchical locality, every symbol is protected by an inner-most local code, and another middle-level code of larger...
We investigate the modulation bandwidth and frequency chirp of transverse-coupled-cavity VCSELs. The simulation shows the 3dB-modulation bandwidth can be doubled and the chirp can also be reduced by a factor of more than two simultaneously.
An intra-cavity loss modulation laser diode (ICLM-LD) was proposed and its characteristics were evaluated numerically and experimentally to realize an ultra wideband direct modulation external cavity laser. It was confirmed that the intra-cavity loss modulation can suppress the modulation sensitivity degradation over the relaxation oscillation frequency, which will be effective to widen the modulation...
In this paper, performance analysis and the effectiveness of Orthogonal Frequency Division Multiplexing (OFDM) for different channels environment has been analyzed and investigated. In order to accomplish these tasks, an OFDM system model has been considered where a random bit sequence is generated and subsequently converted into decimal value depending on the word size of the system. In order to...
Leveraging the design freedom provided by the recently developed polyphase-coded FM (PCFM) waveform structure and the enhanced sensitivity on receive through sidelobe suppression provided by adaptive pulse compression (APC) and its variants, the impact on full polarimetric scattering estimation is examined. By incorporating a Σ-Δ hybrid combiner different polarization modulation schemes are considered...
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