332,396 research outputs found
A Wideband Two-Way Digital Doherty Transmitter in 40nm CMOS
No full textA 40nm CMOS wideband digital Cartesian push-pull inverted Doherty operating in class-E is presented. Wideband Doherty operation is achieved over a 1.9-to-3GHz frequency band, using an off-chip power combining network. The fully digital transmitter (DTX) provides 25.3dBm peak power with a drain/DTX line-up efficiency (DE/SE) of 58.7%/44.9%, respectively, at 2.4GHz. When operated with a 160MHz 256-QAM OFDM signal, it achieves 46.1%/32.7% average DE/SE, with an ACLR and EVM better than −40.6dBc and −33.9dB, respectively, using a simple memory-less digital pre-distortion (DPD).Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic
Helping children think: Gaze aversion and teaching
Full text linkLooking away from an interlocutor's face during demanding cognitive activity can help adults answer challenging arithmetic and verbal-reasoning questions (Glenberg, Schroeder, & Robertson, 1998). However, such `gaze aversion' (GA) is poorly applied by 5-year-old school children (Doherty-Sneddon, Bruce, Bonner, Longbotham, & Doyle, 2002). In Experiment 1 we trained ten 5-year-old children to use GA while thinking about answers to questions. This trained group performed significantly better on challenging questions compared with 10 controls given no GA training. In Experiment 2 we found significant and monotonic age-related increments in spontaneous use of GA across three cohorts of ten 5-year-old school children (mean ages: 5;02, 5;06 and 5;08). Teaching and encouraging GA during challenging cognitive activity promises to be invaluable in promoting learning, particularly during early primary years
A 39 W Fully Digital Wideband Inverted Doherty Transmitter
No full textA high-power fully-digital Doherty transmitter (DDTX) is proposed. It features two segmented LDMOS output switch banks implemented in a custom V T -down-shifted LDMOS technology. A 40 nm CMOS controller digitally activates the individual LDMOS gate segments of the output stage at RF speed. An inverted Doherty power combiner is proposed that features non-short circuited 2 nd harmonic conditions for the main and peak switch banks to boost the RF bandwidth. To guarantee smooth output power and efficiency vs. frequency, a 2 nd harmonic trap is introduced in the power combiner, yielding an RF bandwidth of > 400 MHz. The realized demonstrator can achieve over 39 W peak output power. Its highest drain and system efficiencies, respectively 60 % and 57 %, were found at 34.2 W of output power, while in power back-off its peak drain and system efficiencies are 52 % and 48 % respectively. Over a 25 dB output range, the system efficiency is within 4 percent points of the drain efficiency.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic
Visual signals and children's communication: negative effects on task outcome
Full text linkPrevious research has found that young children fail to adapt to audio-only interaction (e.g. Doherty-Sneddon & Kent, 1996), and perform difficult communication tasks better face-to-face. In this new study, children aged 6- and 10 year-olds were compared in face-to-face and audio-only interaction. A problem-solving communication task involving description of abstract stimuli was employed. When describing the abstract stimuli both groups of children showed evidence of face-to-face interference rather than facilitation. It is concluded that, contrary to previous research, for some communication tasks access to visual signals (such as facial expression and eye gaze) may hinder rather than help children’s communication
K-band combined GaAs monolithic Doherty power amplifier
Full text linkThis paper presents the design, simulations, and measurements of a 35 dBm K-band Doherty power amplifier, fabricated on 0.15μm GaAs monolithic technology of Qorvo. The power amplifier is based on combining on-chip two Doherty modules with a matching power combiner. To demonstrate the power scaling and gain a better insight into the design, the single Doherty module has been fabricated and characterized as well. The Doherty output matching is designed for maximizing the bandwidth and minimizing the components count, with the output capacitance of the active devices determining the impedance inverter impedance. The combined Doherty shows an output power of 35 dBm at 24 GHz, that is almost exactly 3 dB larger than the single Doherty module power module, and with a 6 dB OBO efficiency of 27%, and a gain of 11.5dB. It compares well with the state of the art, representing the highest power GaAs Doherty at similar frequencies
Teachers' responses to children's eye gaze
Full text linkWhen asked questions, children often avert their gaze. Furthermore the frequency of such gaze aversion (GA) is related to the difficulty of cognitive processing (Doherty-Sneddon, Bruce, Bonner, Longbotham & Doyle 2002), suggesting that GA is a good indicator of children’s thinking and comprehension. However, little is known about how teachers detect and interpret such gaze signals. In Study 1 teaching interactions were analysed to determine teachers’ responses to different patterns of children’s eye gaze. In Study 2 a different group of teachers completed a questionnaire assessing teachers’ awareness of GA in determining children’s thinking, understanding and interest. Results showed that teachers did not typically respond to children’s GA in predicted ways and did not associate GA with children’s thinking. However when asked explicitly about GA cues they made predictions relating to question difficulty and children’s thinking in line with empirical work (Doherty-Sneddon et al., 2002). We conclude that whilst teachers have an implicit understanding of GA cues, they typically do not make full use of such cues during classroom teaching
Highly Efficient and Linearity-Enhanced S-band Doherty Power Amplifier
Full text linkThis work presents the design and characterization of a hybrid Doherty power amplifier for S band aiming at enhancing linearity near saturation while maintaining high efficiency. The design combines two highly linear branch amplifiers in a Doherty configuration through a quadrature coupler with reactive termination at the isolated port. At 2.7GHz, the amplifier demonstrates 13.9dB small signal gain, 41dBm saturated power, and 67% maximum efficiency. The linearity is evaluated through two-tone and modulated signal characterizations, showing -30dBc IMD3 up to 36dBm of output power. Additionally, the ACPR is -30dBc and -39dBc, respectively, before and after digital predistortion
Doherty, O J, 414863
No full textThis record was harvested from a previous catalogue system and will be withdrawn in 2025. Information in this record may be superseded or incomplete. Visit this record in UMA's new catalogue at: https://archives.library.unimelb.edu.au/nodes/view/382077Surname: DOHERTY. Given Name(s) or Initials: O J. Military Service Number or Last Known Location: 414863. Missing, Wounded and Prisoner of War Enquiry Card Index Number: 54109.212550
Item: [2016.0049.14370] "Doherty, O J, 414863
The Doherty Power Amplifier: Review of Recent Solutions and Trends
Full text linkIn this paper, an extensive review of the most up-to-date papers on microwave Doherty power amplifiers is presented. The main applications are discussed, together with the employed semiconductor technologies. The different research trends, all aimed to improve the advantages of the Doherty scheme and to solve its inherent drawbacks, are presented. The first considered topic is the maximization of efficiency and/or linearity, where analog and digital techniques are exploited. Another important trend is the bandwidth enlargement of the Doherty architecture, that involves a large number of papers. Multi-band, multi-mode solutions are also considered, using either fixed or reconfigurable solutions. The final section is dedicated to the most significant Doherty integrated implementations
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