1,720,968 research outputs found
Il futuro dell'Università_ Premiare i migliori
No full textPolitica di sviluppo dell?università in Italia, dalla governance ai concors
Valutazione di progetti ex-ante ed ex-post di ricerche industriali su bandi regionali: Umbria, Marche.,Campania, Lazio,.Liguria, Piemonte
No full textRiconoscimento e valutazione spin.off
No full textproposte di accettazione di nuove imprese su richiesta del MIU
Valutazione progetti ricerca applicata
No full textdiversi rapporti che sintetizzano e valutano progetti di ricerca presentati al MIU
Intermodulation Noise in Translinear Filters
No full textWe examine the noise properties of translinear filters operated in class A and class AB, discussing how the output noise power depends on the circuit topology. We use the simplest first order low pass filter built with four BJTs. We show that for in band useful signal the output noise does not depend on the relative position of the transistors in the filter. For class A operation we show that, with a proper choice of the circuit topology, an out of band interfering signal does not add any noise in the average to the output. For class B operation the output noise is due to intermodulation between internal noise sources and signal; the noise power grows with the signal power. For class B operation and out of band interfering signal we calculate that, depending on the circuit topology, the output noise power is reduced by 1.5 or 3.9 dB as compared with the output noise due to an in band signal of the same power
Noise in VCO and PLL - Noise figure control in LNA
No full textNoise in VCO and PLL:
Noise properties of VCO and PLL, key components of modern telecommunication systems, have
been studied. Noise due to internal white noise sources in steady-state oscillators is well described
by random walk phase noise, that causes zero-crossing jitter, plus amplitude noise, that is usually
negligible in applications. In VCO, the control voltage does a®ect not only the frequency, but noise
sources too; starting from this observation, accounting for the intermodulation between control
signal and noise sources, a model for phase noise in VCO when a time varying control signal is
applied has been developed and tested with simulations. Preliminary results regarding square wave
modulation are available for now.
Noise figure control in LNA:
Continued in 2005 the cooperation with the RF Group on the study of noise ̄gure control techniques
in LNA, mainly for cellular phones and portable terminals. In the context of re-con ̄gurable
multistandard, multi-frequency applications, the portable terminal should adapt itself, in addition
to changes in the frequency band of operation, to other time-varying RF environmental conditions,
such as signal strength and blockers strength. Aiming at power consumption reduction, the frontend,
and the LNA in particular, should not be designed to operate always at minimum noise ̄gure,
since noise ̄gure is almost always reduced at the cost of higher power consumption. Signi ̄cant
power saving can be achieved by allowing noise ̄gure to rise, without a®ecting the quality of the
received information, when certain signal strength and blockers strength combinations are met, e.g.
strong signal and weak blockers. Publication of the results is expected in 2006
Noise figure control in LNA - Low-frequency noise reduction in Operational Amplifiers
No full texti - Noise figure control in LNA
Noise figure reduction in LNA for portable terminals and cellular phones have been investigated
in cooperation with the RF group. In demanding applications, such as re-configurable, multistandard,
multi-frequency, the portable terminal should optimize its performances by adapting the
power consuption and noise figure to the different operating conditions in a time-varying environment.
Aiming at longer battery life, maximum signal-to-noise ratio operation is not always the best
choice. In presence of strong signal and weak blockers, signal-to-noise ratio can be lowered without
sacrifying the received information quality, with the advantage of a lower power consumption and
longer battery life. The common gate LNA has been deeply investigated, giving a unified description
of all feedback configurations, providing analytical expressions for gain, noise and linearity
for bipolar and CMOS technology. The flexibility of these structures has suggested a novel design
methodology oriented to configurable low noise amplifiers both in frequency and in performance.
ii - Low-frequency noise reduction in Operational Amplifiers
The limits of the conventional chopper stabilization technique for cancelling the 1/f noise has
been studied theoretically and with simulations, in cooperation with the Microsystems group. The
expected replicas of the 1/f noise at the chopping frequency and its multiples are attenuated by a
modified chopping control, based on the use of a square wave clock with a large amount of phase
jitter, i.e. with a large linewidth. Simulation done using records of real 1/f noise outputs has shown
that the spectrum of the signal is not modified, while 1/f noise replicas are reduced by more than
40 dB. The required circuit for the generation of the chopping signal has been described too; the
resulting overhead with respect to conventional techniques is negligible and fully acceptable
Noise in Class AB Translinear Filters
No full textA specific statistical approach to describe the noise properties of non linear circuits is used. The noise properties of translinear filters operated in class AB are considered. This kind of filter has a dynamic range larger then the maximum signal to noise ratio, and exhibit signal to noise ratio saturation at high signal level. We show how the noise properties depend on the circuit design parameters
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