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There is a growing interest in the use of untethered underwater vehicles. These vehicles require robust and error-free underwater communication for transmission of mission-critical data. In contrast, the requirements for sensor payloads are often less stringent. Depending on the type of data, different Quality-of-Service (QoS) demands can be identified. To maximize the bandwidth utilization of underwater...
This paper presents a power-efficient single-loop continuous-time (CT) third-order sigma delta (ΔΣ) modulator that achieves a SNDR of 79.6 dB over a 10 MHz signal bandwidth. The modulator uses a feedforward-feedback (CIFF-FB) architecture which incorporates a single amplifier biquad (SAB) and a passive integrator to realize a third-order noise shaping. We also propose a continuous-time complementary...
A non-orthogonal multicarrier signal, termed spectrally efficient frequency division multiplexing (SEFDM), is investigated in this work. It improves spectral efficiency by compressing sub-carrier spacing below the symbol rate at the cost of self-created inter carrier interference (ICI). Sphere decoding (SD) is an efficient method to recover signals approaching maximum likelihood (ML) performance....
In this paper a practical application of an electrooptical communication system based on external modulation is reported. The sixteen ATSC TV-channels located at 2.4 GHz, were transmitted over a 30 km of standard optical fiber. The transmitted TV-signal uses Single-Side Band Full Carrier (SSBFC) modulation, allowing in this way an adequate management of the transmitted power and the bandwidth. The...
Despite the high phase non-linearity of a Silicon Mach-Zehnder Modulator in forward bias, we demonstrate that high third order spur-free dynamic range ~102.8 dB. Hz2/3 can be obtained by optimizing the D.C. bias operating point at 1 GHz.
This paper presents a compact audio delta-sigma modulator that features a scalable bandwidth to also support biomedical instrumentation such as digital hearing aids and electromyography, sustaining constant FoMS. The modulator achieves a small die area and low power consumption by exploiting the proposed dynamic gain-bandwidth-boosting (GBWB) scheme in the inverter-based class-AB OTA with minimal...
Many Internet of Things (IoT) applications benefit greatly from low-power long-range connectivity. A promising technology to achieve the low-power and long-range requirements is seen in LoRaWAN, a media access control (MAC) protocol maintained by the LoRa Alliance and leveraging Semtech's patented LoRa radio modulation technology. LoRaWAN provides three different device classes (A, B and C), which...
Meeting the ever-growing information rate demands has become of utmost importance for optical communication systems. However, it has proven to be a challenging task due to the presence of Kerr effects, which have largely been regarded as a major bottleneck for enhancing the achievable information rates in modern optical communications. In this work, the optimisation and performance of digital nonlinearity...
This paper aims to offer insight into the topic of discrete-time ΣΔ ADCs. More specifically, we investigate the impact of non-ideal analog subcircuit parameters on the performance of a 16-bit, 1 kHz, differential second order, 1-bit quantizer, sigma-delta modulator in a 180 nm technology. The parameters in question are OPAMPs slew rate and gain which fulfill the role of fully differential, discrete-time...
The LoRa technology has emerged as an interesting solution for low power, long range loT applications by proposing multiple “degrees of freedom” at the physical layer. This flexibility provides either a long range at the cost of a lower data rate or higher throughput at the cost of low sensitivity, so a shorter range. In this paper, we analyze the flexibility of LoRa and propose various strategies...
Recently, automatic modulation classification techniques using convolutional neural networks on raw IQ samples have been investigated and show promise when compared to more traditional likelihood-based or feature-based techniques. While likelihood-based and feature-based techniques are effective, making classification decisions directly on the raw IQ samples allows for reduced system complexity and...
Low-threshold current and high-speed direct modulation features of membrane-based distributed-feedback (DFB) and distributed-reflector (DR) lasers will be presented. A power conversion efficiency of 12.5% was achieved with the DR laser by adopting a special design to reduce both the waveguide loss and the series resistance.
We demonstrate the modulation bandwidth enhancement in integrated coupled DFB lasers. The coupling strength of the dual DFB is tunable duo to a SOA sandwiching in the center. The 3-dB bandwidth is increased from 8.6 GHz to 18.7 GHz under mutual injection locking.
We demonstrate the development, performance and application of a GaN-based micro-light emitting diode array sharing a common p-electrode with individual-addressed n-electrodes. These individually-addressed n-electrodes minimize the series-resistance difference from conductive paths, and offer compatibility with n-type metal-oxide-semiconductor transistor-based drivers for faster modulation.
New Long-Range radio technologies have recently emerged in the IoT landscape. These technologies work in the Sub-GHz bands, allowing low-power communications over long distances. They are typically based on star-topology networks, where nodes send the data directly to a base station connected to the Internet. One of such technologies is LoRa. Enabled LoRa-based multihop communications would open up...
Directly current-modulated 980-nm vertical-cavity surface-emitting lasers (VCSELs) with oxide-aperture-diameters of 1.5-μm exhibit small-signal −3-dB modulation bandwidths of 31 and 25-GHz and maximum single-mode light-output-powers of 3 and 2-mW at 25 and 85°C, respectively. The side-mode-suppression-ratio exceeds 40-dB at bias currents above threshold.
We report on a photonic downsampling receiver architecture for millimeter-wave communication systems. Conversion loss advantage of >16 dB is shown compared to modulator-based photonic downconversion. 3 Gb/s millimeter-wave communication system performance is demonstrated.
A continuous-time Delta-Sigma modulator (CTDSM) using passive low pass-filter (LPF) in the feedback DAC is proposed. The LPF helps to reduce the signal swing and slew-rate requirements of the first amplifier in CTDSM and also contributes one-order noise shaping. A modulator synthesis is analyzed. The performance of the modulator has been verified through simulations using a standard 0.18-μm CMOS process...
The LPWAN (Low Power Wide Area Network) networks are the evolution of wireless sensor networks directed to the IoT (Internet of Things) concept, which entails sensor connectivity to the Internet. This paper presents a performance evaluation of the LoRa wireless networks. LoRa technology represents a possible solution to the problems of the IoT (Internet of Things) concept. The used frequency bands...
We investigate the effects of large signal dynamics and extinction ratio on the quality of 56 Gbps PAM-4 modulation with 1310 nm, 25G class directly modulated lasers.
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