Device Noise Model Research Articles

Extending quantum probabilistic error cancellation by noise scaling

We propose a general framework for quantum error mitigation that combines and generalizes two techniques: probabilistic error cancellation (PEC) and zero-noise extrapolation (ZNE). Similar to PEC, the proposed method represents ideal operations as linear combinations of noisy operations that are implementable on hardware. However, instead of assuming a fixed level of hardware noise, we extend the set of implementable operations by noise scaling. By construction, this method encompasses both PEC and ZNE as particular cases and allows us to investigate a larger set of hybrid techniques. For example, gate extrapolation can be used to implement PEC without requiring knowledge of the device's noise model, e.g., avoiding gate-set tomography. Alternatively, probabilistic error reduction can be used to estimate expectation values at intermediate virtual noise strengths (below the hardware level), leading to partially mitigated results at a lower sampling cost. Moreover, multiple results obtained with different noise-reduction factors can be further postprocessed with ZNE to better approximate the zero-noise limit.

Conduction Mechanism and Low Frequency Noise Analysis in Al/Pr0.7Ca0.3MnO3 for Bipolar Resistive Switching

The low-frequency noise (LFN) Characteristics of bipolar switching devices consisting of Pt (top)/Al/Pr0.7Ca0.3MnO3 (PCMO)/Pt (bottom) were investigated. The noise spectral density in a low frequency range showed a classical 1/f dependence in both high-resistance state (HRS) and low-resistance state (LRS). The random telegraph noise (RTN) were observed in both HRS and LRS which is due to the AlOx layer acting as traps at the interface between Al and PCMO or traps in PCMO bulk layer. The voltage dependence of the normalized low-frequency spectral density of current fluctuations (Si/I2) presents that the noise properties can be useful indicators to explain the switching mechanism of Al/PCMO device but new noise models should be suggested for the clear approach to analysis of the conduction characteristics in the devices.

Investigation of Phase Noise Generation in Microwave Electron Devices Operating in Nonlinear Regime Exploiting a Flexible Load– and Source–Pull Oscillating Setup

In this paper, we present a flexible measurement setup for the characterization of the phase noise (PN) and frequency stability of microwave electron devices operating under nonlinear oscillating conditions. The setup embeds the device-under-test (DUT) within a feedback loop, and forces it into a large signal (LS) oscillating regime, by controlling the loop amplitude and phase. The DUT input and output terminations are also controlled, by exploiting load- and source-pull capabilities. By exploiting this setup, we demonstrate that the PN performance of microwave oscillators can be strongly affected by the device nonlinear RF working regime. As well known, the oscillator PN is mainly related to the frequency stability of the circuit and the active device low-frequency noise up-conversion to RF mechanisms. By using measurements performed with the proposed setup, it is shown that these aspects depend also on the device LS operating conditions; hence, the dynamic LS load line and the amplifying class of operation have a significant role for the oscillator PN. The experimental results described in the paper, along with the analyses proposed by using simulations, are in accordance with recently published nonlinear noise modeling approaches based on cyclostationary noise sources. The investigation performed by means of the setup can provide information for both the design of low-phase-noise (LPN) oscillators and the parameter extraction and validation of nonlinear noise models of electron devices. Furthermore, this setup is also proposed as a tool for the evaluation of power amplifier PN when a dedicated residual phase noise measurement system is not available.

MODELING OF NOISE BEHAVIOR OF GRADED BAND GAP CHANNEL MOSFET AT GHz FREQUENCIES

A novel graded band gap channel Si - SiGe MOSFET structure has been suggested and its characteristics have been investigated. The investigations indicated that the suggested structure reduces the short-channel effects, increases the cut-off frequency, and hence makes its usage at high frequency and Low noise applications possible. To show the superior performance of the suggested structure at GHz frequencies, and as an example, the noise behavior of the structure is determined. First the device noise model parameters are calculated from D.C. and A.C. characteristics. The extracted noise model parameters are then used to determine the minimum noise figure at GHz frequencies. The effects of the different device parameters on the noise performance are determined. Finally, the results are compared with those of conventional MOSFET structure to show the superior performance of graded band gap Si - SiGe MOSFETs at high frequency ranges.

Artificial neural networks for temperature dependent noise modeling of microwave transistors

In this paper an automated procedure for prediction of microwave transistor noise parameters versus temperature is presented. It is based on an improved Pospieszalski's noise model. In order to avoid extraction of device noise model equivalent circuit parameters (ECP) from the measured scattering and noise parameters for each operating temperature, an artificial neural network is introduced for modeling of the ECP temperature dependence. Therefore, it is necessary to acquire the measured data and extract the ECP only for several operating temperatures used for the network training. Once the network is trained and assigned to the considered noise model, the device noise parameters are easily obtained for each temperature from the operating range. It is done without changes in the network structure and without the need for time consuming and complex measurements and optimiztions.

SpectreHDL as tool for noise analysis of poly-Si TFT circuits

Because of no general noise model in poly-Si TFT technologies, a noise analysis of poly-Si TFT circuits is currently unavailable in any circuit simulator. Therefore it is shown how to make use of the SpectreHDL language for this purpose once the device noise model is extracted from measurement results.

A unified model for high-frequency current noise of MOSFETs

At high frequency, the MOSFET drain current noise and induced gate noise are generally accepted as dominated by the thermal noise as the MOSFET is operating in strong inversion region. However, controversy exists about the high-frequency noise in subthreshold region. This paper proposes unified high-frequency drain current noise and induced gate noise models valid in strong-, moderate- and weak-inversion regions. These models are necessary for the completeness of device noise model and helpful for low-noise high-frequency amplifier design with deep submicrometer technologies with MOSFETs operating in moderate inversion region.

A wide-band on-wafer noise parameter measurement system at 50-75 GHz

A wide-band on-wafer noise parameter measurement system at 50-75 GHz is presented. This measurement system is based on the cold-source method with a computer-controlled waveguide tuner. Calibrations and measurement methods are discussed and measured results for passive and active on-wafer devices are shown over a 50-75 GHz range. An InP high electron-mobility transistor device is used as a test item for the active device. A Monte Carlo analysis to study measurement uncertainties is also shown. The measurement system is a useful tool in the development and verification of device noise models, as well as in device characterization.

A physics-based semiconductor noise model suitable for efficient numerical implementation

A semiconductor device noise model in the framework of semiclassical transport and Pauli's exclusion principle is presented. Terminal current noise is modeled as a direct consequence of electron scattering taking place inside the device at the microscopic level. The approach directly connects electron scattering rates of semiclassical transport theory with the current spectral density at the device terminals. It is shown that the spectral density of steady-state current fluctuations can be obtained from the transient solution of the Boltzmann transport equation with special initial conditions. This formulation is inherently suitable for deterministic solution techniques, for instance, the computationally efficient spherical harmonics method. Approximating the instantaneous value of the occupation number by the occupation probability, this model is able to account for Pauli's principle and at the same time describe the behavior of the electron ensemble in terms of independent entities. As a practical demonstration, the model is employed to compute the current noise spectral density due to generation recombination and acoustic and optical phonon scattering for bulk n-type silicon material. Additionally, in order to add more physical insight and to verify results, the model is also employed to compute the low-frequency current spectral density as a function of the electric field and temperature, respectively. The results show good agreement with low-frequency noise measurements reported in literature.

Nonlinear device noise models: Satisfying the thermodynamic requirements

This paper proposes three tests to determine whether a given nonlinear device noise model is in agreement with accepted thermodynamic principles. These tests are applied to several models. One conclusion is that the standard Gaussian noise models for nonlinear devices predict thermodynamically impossible circuit behavior: those models should be abandoned. But the nonlinear shot-noise model predicts thermodynamically acceptable behavior under a constraint derived here. Further, this constraint specifies the current noise amplitude at each operating point from knowledge of the device /spl upsi/-i curve alone. This paper shows how the thermodynamic requirements can be reduced to concise mathematical tests, involving no approximations, for the Gaussian and shot-noise models.