Amplifier

About: Amplifier is a research topic. Over the lifetime, 163941 publications have been published within this topic receiving 1361964 citations. The topic is also known as: amp & amplifier.

Ytterbium-doped fiber amplifiers

Abstract: The ytterbium-doped fiber amplifier offers a number of attractive features, including a broad-gain bandwidth and a high efficiency, due in large part to its freedom from various competing processes seen in other rare-earth dopants. Here we discuss the main features that influence design and possible applications of ytterbium-doped fiber amplifiers.

Design of analog integrated circuits and systems

Abstract: MOS transistor models bipolar transistor models feedback and sensitivity in analogue integrated circuits elementary transistor stages behavioural modelling of operational and transconductance amplifiers operational amplifier design fundamentals of continuous-time and sampled-data active filters design and implementation of integrated active filters.

Control apparatus for electrosurgical generator power output

Abstract: A power control apparatus for an electrosurgical generator (10) is used for controlling output power from the generator (10) to the tissue or bodily fluids of a patient (11). The control apparatus rapidly determines the range of impedance of the load on the electrosurgical generator (10) and adjusts the output power accordingly. Output current and output voltage from the electrosurgical generator (10) are monitored and sent to a microprocessor (18). The microprocessor (18) runs an algorithm that rapidly determines the impedance range of the load on the generator (10). The algorithm uses computational techniques, such as comparisons and bit shifting, that avoid long division and other time-consuming operations. The microprocessor (18) can then adjust a high voltage power supply (15) that effects the radio frequency amplifier stage. A method for controlling the power of the electrosurgical generator (10), including steps in the algorithm, is also disclosed.

Ultrasonic surgical handpiece and an energy initiator

Abstract: An ultrasonic oscillator drives a tool at a set frequency. An amplitude control runs the oscillator to set the vibration level. A frequency regulator joins the amplitude and the oscillator. A control feedback loop, in the frequency regulator, keeps handpiece linear dynamics. An operational transconductance amplifier, in the oscillator, governs gain of the loop. A circuit connects to the control to retard the rate of current application over time to the amplifier. The circuit has switching to either retard the rate or reset for start up. The amplifier is a current output device with current directly proportional to the bias current and input voltage with bias as gain change for the loop. The circuit limits the bias to the amplifier to modify frequency response and output current. A capacitor delays application of the bias to the amplifier. Replaceable tools of various lengths or shapes positioned along an axis vibrate for surgery at the frequency and a wave length. Tools longer than one wavelength and of configurations tuned to oscillate around the frequency resonate as a function of their material, length and configuration. A flue surrounds the tool and has a hollow elongate semi rigid central body about an axis with a funnel, at one end thereof and a nozzle, at the other to direct annular irrigant/coolant flow therethrough. The funnel and nozzle are resilient. Reinforcing ridges, inside the nozzle, act to maintain concentricity between the flue and nozzle tip and channel irrigant thereabout.

Wide-band CMOS low-noise amplifier exploiting thermal noise canceling

Abstract: Known elementary wide-band amplifiers suffer from a fundamental tradeoff between noise figure (NF) and source impedance matching, which limits the NF to values typically above 3 dB. Global negative feedback can be used to break this tradeoff, however, at the price of potential instability. In contrast, this paper presents a feedforward noise-canceling technique, which allows for simultaneous noise and impedance matching, while canceling the noise and distortion contributions of the matching device. This allows for designing wide-band impedance-matching amplifiers with NF well below 3 dB, without suffering from instability issues. An amplifier realized in 0.25-/spl mu/m standard CMOS shows NF values below 2.4 dB over more than one decade of bandwidth (i.e., 150-2000 MHz) and below 2 dB over more than two octaves (i.e., 250-1100 MHz). Furthermore, the total voltage gain is 13.7 dB, the -3-dB bandwidth is from 2 MHz to 1.6 GHz, the IIP2 is +12 dBm, and the IIP3 is 0 dBm. The LNA drains 14 mA from a 2.5-V supply and the die area is 0.3/spl times/0.25 mm/sup 2/.