1,721,174 research outputs found
A time-variant analysis of fundamental 1/f3 phase noise in CMOS parallel LC-tank quadrature oscillators
No full textThis paper presents a rigorous time-variant analysis of the 1/f MOS device noise upconversion into 1/f^3 phase noise for two of the most popular parallel-coupled quadrature CMOS harmonic oscillators. Simple closed-form equations for the fundamental 1/f^3 phase-noise spectrum are derived and validated through SpectreRF simulations, proving that the two topologies display remarkably different sensitivities to the low-frequency noise sources. Based on the developed analysis, useful general design insights are also presented
Harmonic Oscillators in CMOS—A Tutorial Overview
Full text linkThe harmonic oscillator is a truly irreplaceable as well as ubiquitous analog integrated circuit. Starting from the basics of its CMOS implementation, we will discuss the phase noise of the harmonic oscillator in some detail, where the intrinsic large-signal operation mandates a time-variant analysis. This will be followed by a survey of the most popular design techniques enabling a low phase noise and a wide range of oscillation frequencies
A Power-Scalable DCO for Multi-Standard GSM/WCDMA Frequency Synthesizers
No full textA Digitally Controlled Oscillator (DCO) whose power consumption can be reconfigured while maintaining an almost constant phase-noise figure-of-merit (FoM). This is achieved by using either a single-switch-pair or a complementary (i.e., double-switch-pair) oscillator topology, without disturbing the optimized LC tank of the DCO. The optimal power consumption in the complementary (P-N) configuration is reduced by 75% compared to the single-switch-pair (N-only) configuration, while the FoM is kept constant. Measurements on a 55 nm CMOS 4 GHz DCO prototype show a minimum phase noise of -129.3 dBc/Hz at 2 MHz offset from the carrier in the P-N configuration, and of -134.7 dBc/Hz in the N-only configuration, with a phase noise difference very close to the 6 dB expected from theory. The current consumption is 6 mA and 24 mA, respectively, resulting in approximately the same FoM of -185 dBc/Hz
On the Remarkable Performance of the Series-Resonance CMOS Oscillator
No full textCommon harmonic oscillator topologies, such as class-B and class-C, are typically unable to meet ultra stringent phase noise requirements, due to the exceedingly large capacitance (and, symmetrically, low inductance) that would be required in the parallel resonator. In this paper, we show that an oscillator making use of series resonators is ideally able to overcome this limitation, with the additional, surprising benefit that the phase noise contribution from the active oscillator core can be made negligible, provided that very good MOS switches are available
A 19.5-GHz 28-nm Class-C CMOS VCO, With a Reasonably Rigorous Result on 1/f Noise Upconversion Caused by Short-Channel Effects
No full textClass-C operation is leveraged to implement a K-band CMOS voltage-controlled oscillator (VCO) where the upconversion of 1/f current noise from the cross-coupled transistors in the oscillator core is robustly contained at a very low level. Implemented in a bulk 28-nm CMOS technology, the 12%-tuning-range VCO shows a phase noise as low as -112 dBc/Hz at 1-MHz offset (-86 dBc/Hz at 100 kHz offset) from a 19.5 GHz carrier while consuming 20.7 mW, achieving a figure of merit (FoM) of -185 dBc/Hz. The design is complemented by a theoretical investigation of 1/f noise upconversion caused by short-channel effects in the cross-coupled transistors, obtaining the first instance of a closed-form phase noise expression in the 1/f3 region
Analysis and Design of a 17-GHz All-npn Push-Pull Class-C VCO
No full textA push-pull oscillator topology that uses only one type of active device is proposed in this article. A magnetic transformer is leveraged to set positive feedback around a common-collector differential npn transistor pair, implementing the push-pull operation. This results in half the bias current for a given amplitude of oscillation, compared to more standard oscillator topologies. A thorough phase noise analysis of the circuit is carried out, emphasizing the crucial role of the magnetic transformer in the circuit operation and noise optimization. Proof-of-concept prototypes implemented in a 130-nm SiGe BiCMOS technology operate at 17 GHz and show a phase noise as low as -116 dBc/Hz at 1-MHz offset, while drawing 13.7 mA from the 3.3-V supply. The tuning range is 15%. While the circuit is demonstrated in SiGe BiCMOS technology, it lends itself equally well to implementations in other technologies where only one fast device is available, such as SiGe HBT, InP HBT, and GaN HEMT
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Reduced Impact of Induced Gate Noise on Inductively Degenerated LNAs in Deep Submicron CMOS Technologies
No full textDesigners of radio-frequency inductively-degenerated CMOS low-noise-amplifiers have usually not followed the guidelines for achieving minimum noise figure. Nonetheless, state-of-the- art implementations display noise figure values very close to the theoretical minimum. In this paper, we point out that this is due to the effect of the parasitic overlap capacitances in the MOS device. In particular, we show that overlap capacitances lead to a significant induced-gate-noise reduction, especially when deep sub-micron CMOS processes are used
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