Amplificateur pour guitare électrique

thumb|Amplificateur Fender au format « stack » Un amplificateur pour guitare est un amplificateur audio, spécialement conçu pour la guitare électrique, ou la guitare basse. Le terme abrégé « ampli » désigne communément le couple constitué par l'amplificateur électronique et le haut-parleur. La partie électronique et le haut-parleur peuvent se présenter en deux éléments distincts, ou être réunis dans un même meuble, construit le plus souvent en plaques de bois, recouvert d'un revêtement en vinyle. Quand ils sont séparés, la partie électronique s'appelle une « tête d'ampli », et celle contenant le(s) haut-parleur(s) un « baffle ». L'ensemble constitue un « stack » (deux corps). Quand ils sont réunis dans un même élément, on parle de « combo ». Caractéristiques spécifiques On ne recherche pas les mêmes qualités de son dans un amplificateur pour guitare électrique que dans un amplificateur audio d'usage général. Ce dernier reçoit un signal électrique bien calibré, que l'o

A Low Power Super-Regenerative Impulse Radio Ultra-Wideband Receiver in CMOS Technology

Communication systems have played a key role in changing our lives as such systems help to access remote data and to transfer it to the end user when requested. Intelligent nodes, which can process and transmit information placed in a given environment can provide localized data that might not be available through a public network such as the internet. As an example, nodes can provide dynamic data such as room temperature, chemical composition of air, or light intensity level. With the progress made in the semiconductor industry, such nodes have become compact, thereby making it easier to setup a cluster in a confined place. Often these nodes are to be placed in a remote location and hence the use of a cable to power up these devices might not be possible. Also, the use of cables makes the system bulky and heavy. For this reason battery-powered wireless sensor nodes are desirable. Such battery operated devices need to be energy efficient to avoid replacing the batteries often. Energy efficiency can be achieved by optimizing several parameters from the top (system level architecture) to the bottom (transistor level design). The thesis describes a receiver system design for Impulse-radio Ultra-Wideband (IR-UWB) signalling standard proposed in IEEE 802.11.4a for short range, low data rate communication system. The advantages of the IR-UWB signalling scheme over other existing standards and a comparison between various receiver architectures for IR-UWB standard using energy consumption as a metric is described. The main power consuming block in an IR-UWB receiver is identified to be the front-end amplifier structure as it needs to provide sufficient gain for proper operation of the subsequent stages. To reduce the power consumption of this amplifier, the super-regenerative architecture for IR-UWB system is proposed. It is shown in this work that since the super-regenerative receiver uses an amplifier with positive feedback, it can achieve high gain with a relatively low current, hence it can significantly reduce the power consumption. The super-regenerative receiver for the IR-UWB system is implemented in a 0.18 µm CMOS technology operating at 1.5 V, and the receiver energy consumption is 0.24 nJ/bit at a data rate of 10 Mbps. The receiver achieves a measured sensitivity of -66 and -61 dBm at 3.494 and 3.993 GHz, respectively, with a BER of 10-3. Finally, an automatic tuning circuitry based on a digital phase-locked loop architecture (DPLL) for super-regenerative receiver is proposed. The objective is to tune the receiver to either one of the sub-bands (3.494 or 3.993 GHz) as proposed in the IEEE 802.15.4a standard. Including the tuning circuitry helps to improve the receiver sensitivity, and also demonstrates the possibility for multi-band reception using such an architecture. The proposed DPLL is implemented in a 0.18 µm CMOS technology consuming 9.3 mW.

EPFL2010

High-Gain Solid-State and Fiber Amplifier-Chain for High-Power Coherent Communication

René Dändliker

We report on the experimental results of a dual-stage amplifier combining a Nd-doped double-clad fiber and a Nd-doped YAG crystal. We obtained up to 3.5-W single-mode single-frequency output power with 28-dB gain. This is, to the best of our knowledge, the first demonstration of a dual-stage amplifier combining doped fibers and solid-state amplifiers.

1999

A Low Power Super-Regenerative Impulse Radio Ultra-Wideband Receiver in CMOS Technology

EPFL2010