Load-mismatch sensitivity of class-E power amplifiers

Class-E RF power amplifiers (PAs) are very power efficient under nominal operating conditions. Due to incorporating two tuned tanks, the dependence on the load impedance is, however, relatively large, resulting in, e.g., load-dependent output power, power efficiency, peak voltages, and peak (and average) currents which can lead to reliability issues. This paper presents load-pull analyses for class-E RF PAs from a mathematical perspective, with analyses and discussions of the effects of the most common nonidealities of class-E PAs: the limited loaded quality factor (Qloaded) of the series filter, switch on-resistance, the limited quality factor of the dc-feed inductor, load mismatch-dependent switch conduction loss, and the limited negative voltage excursions (due to, e.g., the reverse conduction of the switch transistor for negative voltage excursions). The theoretical findings are backed up by extensive circuit simulations and load-pull measurements of a class-E PA implemented in 65-nm CMOS technology. The PA provides 18.1-dBm output power and 72% efficiency at 1.4 GHz under nominal operating condition employing an off-chip matching network

Efficiency enhancement techniques for RF and millimeter wave power amplifiers

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 123-126).Power amplifiers are the circuit blocks in wireless transceivers that require the largest power budget because of their relatively low efficiencies. RF designers cannot depend solely on the development better semiconductor devices in advanced deeply scaled process technologies to obtain improved power amplifier performance. The development of new and better circuits, architectures and design methodologies to maximally exploit the available semiconductor devices is very important as well. This thesis investigates a number of techniques that can be used to improve the efficiency of power amplifiers and break the power-frequency tradeoff in power amplifier design. The first technique emphasizes the use of a class E tuned output network as an efficiency enhancement tool for power amplifiers regardless of their bias conditions. A Class E tuned CMOS power amplifier (PA) operating in the 60 GHz band was designed. Design, layout, and parasitic modeling considerations to attain high-efficiency millimeter-wave PA operation are discussed. Both single-ended and differential versions of the single-stage PA were implemented in a 32 nm SOI CMOS process. Peak power added efficiency of 27% (30%), power gain of 8.8 dB (10 dB), and saturated output power > 9 dBm (12.5 dBm) were measured at 60 GHz from the single-ended (differential) PA with 0.9 V supply. The second technique investigated the efficacy of resistance compression networks in an energy recycling network operating at multi-gigahertz frequencies. The resistance compression network reduces the variation in resonant rectifier input impedance seen at the isolation port of an isolating power combiner. The system was operated at 2.14 GHz and was built around Schottky barrier diodes custom fabricated in a 0.13 [mu]m CMOS process. It is the first experimental demonstration that resistance compression networks can be used for energy recycling in multi-gigahertz applications.by Olumuyiwa Temitope Ogunnika.Ph.D

Trade-off analysis of modes of data handling for earth resources (ERS), volume 2

For abstract, see N75-26470

Space programs summary no. 37-32, volume iv, for the period 1 february - 31 march 1965. supporting research and advanced development

Space programs on telecommunications, space science, propulsion, engineer mechanics, guidance and control, systems, and project engineerin

Proceedings of the Second International Mobile Satellite Conference (IMSC 1990)

Presented here are the proceedings of the Second International Mobile Satellite Conference (IMSC), held June 17-20, 1990 in Ottawa, Canada. Topics covered include future mobile satellite communications concepts, aeronautical applications, modulation and coding, propagation and experimental systems, mobile terminal equipment, network architecture and control, regulatory and policy considerations, vehicle antennas, and speech compression

Study to determine potential flight applications and human factors design guidelines for voice recognition and synthesis systems

A study was conducted to determine potential commercial aircraft flight deck applications and implementation guidelines for voice recognition and synthesis. At first, a survey of voice recognition and synthesis technology was undertaken to develop a working knowledge base. Then, numerous potential aircraft and simulator flight deck voice applications were identified and each proposed application was rated on a number of criteria in order to achieve an overall payoff rating. The potential voice recognition applications fell into five general categories: programming, interrogation, data entry, switch and mode selection, and continuous/time-critical action control. The ratings of the first three categories showed the most promise of being beneficial to flight deck operations. Possible applications of voice synthesis systems were categorized as automatic or pilot selectable and many were rated as being potentially beneficial. In addition, voice system implementation guidelines and pertinent performance criteria are proposed. Finally, the findings of this study are compared with those made in a recent NASA study of a 1995 transport concept

Multirate Frequency Transformations: Wideband AM-FM Demodulation with Applications to Signal Processing and Communications

The AM-FM (amplitude & frequency modulation) signal model finds numerous applications in image processing, communications, and speech processing. The traditional approaches towards demodulation of signals in this category are the analytic signal approach, frequency tracking, or the energy operator approach. These approaches however, assume that the amplitude and frequency components are slowly time-varying, e.g., narrowband and incur significant demodulation error in the wideband scenarios. In this thesis, we extend a two-stage approach towards wideband AM-FM demodulation that combines multirate frequency transformations (MFT) enacted through a combination of multirate systems with traditional demodulation techniques, e.g., the Teager-Kasiser energy operator demodulation (ESA) approach to large wideband to narrowband conversion factors. The MFT module comprises of multirate interpolation and heterodyning and converts the wideband AM-FM signal into a narrowband signal, while the demodulation module such as ESA demodulates the narrowband signal into constituent amplitude and frequency components that are then transformed back to yield estimates for the wideband signal. This MFT-ESA approach is then applied to the various problems of: (a) wideband image demodulation and fingerprint demodulation, where multidimensional energy separation is employed, (b) wideband first-formant demodulation in vowels, and (c) wideband CPM demodulation with partial response signaling, to demonstrate its validity in both monocomponent and multicomponent scenarios as an effective multicomponent AM-FM signal demodulation and analysis technique for image processing, speech processing, and communications based applications