Proc. SPIE. 6600, Noise and Fluctuations in Circuits, Devices, and Materials
KEYWORDS: Signal to noise ratio, Data modeling, Interference (communication), Amplifiers, Distortion, Signal processing, Nonlinear optics, Chemical elements, Optimization (mathematics), Electronic circuits
We investigate the possibility of building linear amplifiers capable of enhancing the Signal-to-Noise and Distortion
Ratio (SNDR) of sinusoidal input signals using simple non-linear elements. Other works have proven that it is
possible to enhance the Signal-to-Noise Ratio (SNR) by using limiters. In this work we study a soft limiter
non-linear element with and without hysteresis. We show that the SNDR of sinusoidal signals can be enhanced
by 0.94 dB using a wideband soft limiter and up to 9.68 dB using a wideband soft limiter with hysteresis. These
results indicate that linear amplifiers could be constructed using non-linear circuits with hysteresis. This paper
presents mathematical descriptions for the non-linear elements using statistical parameters. Using these models,
the input-output SNDR enhancement is obtained by optimizing the non-linear transfer function parameters to
maximize the output SNDR.
Technology advances tend to reduce minimum dimensions and source voltages to maintain scaling rules. Both scaling trends make noise more critical, reduce yield and increase device parameter fluctuations. This paper presents a statistical model that permits the study of noise and parameter deviations on gates. Using this model stochastic resonance (SR) is studied both in single devices and arrays for subthreshold and suprathreshold input signals. The SR is measured by the signal-to-noise ratio (SNR) in the time domain and a modified SNR is proposed to take into account all the effects induced by noise in gates. With this measure subthreshold and suprathreshold SR is reviewed. Finally, a discussion of the possibility of considering noise a part of the electronic circuits is presented, suggesting that it could be a solution to some of the emerging problems in future nanotechnologies.
Proc. SPIE. 5467, Fluctuations and Noise in Biological, Biophysical, and Biomedical Systems II
KEYWORDS: Signal to noise ratio, Switching, Interference (communication), Signal processing, Electronic circuits, Signal detection, Stochastic processes, Systems modeling, Resonance enhancement, Neurons
Noise is a key factor in information processing systems. This fact will be even more critical in new technologies, as dimensions continue to scale down. New design methodologies tolerant to or even taking advantage of noise need to be considered. In this work the possibility of using stochastic resonance (SR) in electronic circuits is studied. We demonstrate the validity of nearly any kind of perturbing signal in producing a noise resonance, thus extending the stochastic resonance concept. In this paper we have explored stochastic, chaotic, deterministic and coupled noise perturbations. The relationship between input signal and input noise amplitude on the noise resonance regime is analyzed, providing a rule for operation under this situation. Finally, we present a simulation study demonstrating that noise resonance is robust to non-ideal behaviors of non-linear devices. All three facts allow direct use of generalized noise resonance (GNR) in electronic circuits.
The application of Shape Memory Alloys (SMA) in mechanical engineering (ME) or in civil engineering (CE) requires the tuning of the physical properties with each particular need. When the target involves dampers for quakes in CE the number of full working cycles is relatively small (i.e. 200) but the application requires guaranteed behavior after several years of inactivity. On the contrary some devices in ME may need relatively high frequencies operating for a long period of time. In this work the mesoscopic effects in the SMA are quantified to ensure guaranteed behavior in the frame of dampers for CE applications. For instance, the actions of accumulated deformation in cycling and the changes induced by external temperature (i.e., summer-winter) are evaluated. Also, the perturbations induced by diffusive (induced by phase metastability, i.e. produced by microscopic interactions) are considered. In particular, the phase coexistence effects are visualized in Cu-based and partially in NiTi alloys. The practical creep induced by cycling and the coexistence actions are decisive in damping applications.