Some investigations in the area of high voltage, high current D-C amplifiers /

Issued also as thesis (M.S.) University of Illinois.

Molecular bandpass amplifiers. Contract AF33(616)-7252. Interim scientific report no. 1- [of the] Development Laboratory, Semiconductor Division, Hughes Aircraft Co.

Mode of access: Internet.

Switching-mode audio amplifier /

Issued also as thesis (M.S.) University of Illinois.

Design and development of LCRE fission-counter preamplifier /

"Contract AT(30-1)-2789."

Direct support and general support maintenance repair parts and special tools list for precision amplifier, Krohn-Hite model 7500 (NSN 6695-01-081-9053).

Includes index.

DS, GS, and depot maintenance manual : radio sets AN/VRC-53, AN/VRC-64, AN/GRC-125, and AN/GRC-160 and amplifier-power supply groups, OA-3633/GRC and OA-3633A/GRC.

"December 1969."

Direct support and general support maintenance repair parts and special tools list (including depot maintenance repair parts and special tools) for radio sets AN/VRC-53, AN/VRC-64, AN/GRC-125, and AN/GRC-160 and amplifier, power supply groups OA-3633/GRC and OA-3633A/GRC (parts list for OA-3633/GRC and OA-3633A/GRC, NSN 5820-00-973-3383, only).

Includes index.

General support maintenance manual : amplifier-converter AM-6879/URC (NSN 5820-01-070-1950).

Includes index.

Organizational, direct support, general support, and depot maintenance manual, including repair parts and special tools lists : amplifier, electronic control, AM-3209/ASN.

"October 1965."

Operator's and organizational maintenance manual : amplifier, radio frequency AM-1881/U.

"28 July 1960."

Field and depot maintenance manual : amplifier, radio frequency AM-1881/U.

"17 February 1961."

Operator's manual : amplifier group OG-181/VRC, (NSN 5895-01-172-2923).

Includes index.

Electroluminiscence and optical amplification in silicon nanostructures: towards the integration of electronics and photonics

This line of research of my group intends to establish a Silicon technological platform in the field of photonics allowing the development of a wide set of applications. Particularly, what is still lacking in Silicon Photonics is an efficient and integrable light source such an LED or laser. Nanocrystals in silicon oxide or nitride matrices have been recently demonstrated as competitive materials for both active components (electrically and optically driven light emitters and optical amplifiers) and passive ones (waveguides and modulators). The final goal is the achievement of a complete integration of electronic and optical functions in the same CMOS chip. The first part of this paper will introduce the structural and optical properties of LEDs fabricated from silicon nanostructures. The second will treat the interaction of such nanocrystals with rare-earth elements (Er), which lead to an efficient hybrid system emitting in the third window of optical fibers. I will present the fabrication and assessment of optical waveguide amplifiers at 1.54 ¿m for which we have been able to demonstrate recently optical gain in waveguides made from sputtered silicon suboxide materials.

Envelope amplifier based on switching capacitors for high efficiency RF amplifiers

Modern transmitters usually have to amplify and transmit signals with simultaneous envelope and phase modulation. Due to this property of the transmitted signal, linear power amplifiers (class A, B, or AB) are usually used as a solution for the power amplifier stage. These amplifiers have high linearity, but suffer from low efficiency when the transmitted signal has high peak-to-average power ratio. The Kahn envelope elimination and restoration technique is used to enhance the efficiency of RF transmitters, by combining highly efficient, nonlinear RF amplifier (class E) with a highly efficient envelope amplifier in order to obtain a linear and highly efficient RF amplifier. This paper presents a solution for the envelope amplifier based on a multilevel converter in series with a linear regulator. The multilevel converter is implemented by employing voltage dividers based on switching capacitors. The implemented envelope amplifier can reproduce any signal with a maximum spectral component of 2 MHz and give instantaneous maximum power of 50 W. The efficiency measurements show that when the signals with low average value are transmitted, the implemented prototypes have up to 20% higher efficiency than linear regulators used as a conventional solution.

Modeling Reflective Bistability in Vertical-Cavity Semiconductor Optical Amplifiers

The characteristics of optical bistability in a vertical- cavity semiconductor optical amplifier (VCSOA) operated in reflection are reported. The dependences of the optical bistability in VCSOAs on the initial phase detuning and on the applied bias current are analyzed. The optical bistability is also studied for different numbers of superimposed periods in the top distributed bragg reflector (DBR) that conform the internal cavity of the device. The appearance of the X-bistable and the clockwise bistable loops is predicted theoretically in a VCSOA operated in reflection for the first time, to the best of our knowledge. Moreover, it is also predicted that the control of the VCSOA’s top reflectivity by the addition of new superimposed periods in its top DBR reduces by one order of magnitude the input power needed for the assessment of the X- and the clockwise bistable loop, compared to that required in in-plane semiconductor optical amplifiers. These results, added to the ease of fabricating two-dimensional arrays of this kind of device could be useful for the development of new optical logic or optical signal regeneration devices.