Pospieszalski Noise Model Research Articles

An improved noise model of InP HEMT for millimeter wave application

AbstractA new temperature noise model, including the influence of gate‐drain series resistance Rgd on the noise performance for an InP HEMT, is presented in this article. An equivalent temperature Tgd of Rgd has been taken into account based on Pospieszalski's noise model. The corresponding extraction procedure of noise parameters is given. Good correlation between the simulated and measured noise parameters in the frequency range of 8–50 GHz for a wide range of bias points verify the validity of the improved noise model.

Dependence of noise temperature on physical temperature for cryogenic low-noise amplifiers

We present the results of noise-temperature measurements for four radio astronomy MMIC low-noise amplifiers (LNAs) at physical temperatures from 2 to 160 K. We observe and confirm recent reports that the noise temperature of an LNA exhibits a quadratic dependence with respect to the physical temperature. We are also able to confirm the prediction by Pospieszalski that below a certain physical temperature there is no further significant reduction in noise temperature. We then discuss these results in the context of both the Pospieszalski noise model and some recent Monte-Carlo simulations, which have implied that at very low temperatures, heating of the electron channel above ambient temperature may help to explain the behavior of the drain temperature parameter.

Novel neural approach for parameter extraction of microwave transistor noise models

AbstractA novel approach for parameter extraction of microwave transistor noise models based on artificial neural networks is proposed in this work. Neural networks are applied to determine parameters of the noise model directly from the measured noise and small‐signal scattering parameters without any optimization procedure. Moreover, unlike the similar existing procedures, development of the extraction procedure does not require any measured data or optimizations in a circuit simulator, making the procedure more efficient, as described in detail in the paper. The approach has been applied to extraction of the Pospieszalski's noise model parameters for a specific pseudomorphic high‐electron‐mobility transistor (pHEMT) device working under different temperatures. Copyright © 2015 John Wiley & Sons, Ltd.

A novel theoretical analysis for the determination of the noise parameters applicable to millimeter‐wave frequencies (invited)

SummaryThis paper describes in detail a novel, fully analytical technique for the determination of high frequency noise parameters. The technique can be applied at any frequency of interest because the requirement of an external tuner is dropped. The absence of an input tuner removes the practical constraint of operational bandwidth of the system and opens the door to the direct evaluation of noise parameters of active devices in frequency ranges currently inaccessible. The mathematical formulation at the basis of the present technique is applied to the Pospieszalski noise model and is described in detail. The new technique provides an analytical tool to determine the equivalent noise temperatures Tgs and Tds against measured data over a broad frequency range. Limitations and opportunities of the new technique are discussed including new insights into the Pospieszalski noise model. Copyright © 2015 John Wiley & Sons, Ltd.

Noise Measurements of Discrete HEMT Transistors and Application to Wideband Very Low-Noise Amplifiers

The noise models of InP and GaAs HEMTs are compared with measurements at both 300 and 20 K. The critical parameter, Tdrain, in the Pospieszalski noise model is determined as a function of drain current by measurements of the 1-GHz noise of discrete transistors with 50- Ω generator impedance. The dc I-V for the transistors under test are presented and effects of impact-ionization are noted. InP devices with both 100% and 75% indium mole fraction in channel are included. Examples of the design and measurement of very wideband low-noise amplifiers (LNAs) using the tested transistors are presented. At 20-K physical temperature the GaAs LNA achieves 10-K noise over the 0.7-16-GHz range with 16 mW of power and an InP LNA measures 20-K noise over the 6-50-GHz range with 30 mW of power.

On the Excess Noise Factor $\Gamma$ of a FET Driven by a Capacitive Source

The excess noise factor Γ , also known as Ogawa's noise factor, is frequently used in the literature on optical receivers to calculate the noise and sensitivity of FET front-ends. After revisiting its definition and clarifying its applications and limitations, we derive an analytical expression for Γ in terms of the channel noise factor γ, the gate noise factor δ , and the correlation coefficient c. We explain the difference between Γ and γ and discuss the dependence of Γ on the source (photodetector) capacitance. The latter dependence, which is weaker than previously thought, is verified by circuit simulations. Additional insight is obtained by complementing van der Ziel's noise model with Pospieszalski's noise model. Finally, we use the derived expression for Γ to calculate its value from measured noise data of a 0.18- μm CMOS technology.

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.

Low‐temperature solutions for UMTS base‐station receivers using superconducting and low‐noise active filtering techniques

AbstractThe different steps of a cryogenic low‐noise amplifier design are presented. The noise parameters of a HEMT transistor are measured and used to determinate the Pospieszalski noise model 1. This noise model is used for the design of a one‐stage LNA for which the matching circuits are realised with superconductor material for optimal noise performances. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 242–245, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11341

The Pospieszalski noise model and the imaginary part of the optimum noise source impedance of extrinsic or packaged FET's

The imaginary part X(S/sub opt/) of the optimum noise impedance for extrinsic or packaged devices is investigated. The analysis modifies the well-known Pospieszalski noise model by applying a series feedback to the source port. A simple expression for X(S/sub opt/) is developed and is verified for extrinsic and packaged devices with a decreasing level of accuracy. The results give further insights into the way the parasitic inductors L/sub g/ and L/sub s/ affect the noise performance of the transistor and can help to design low-noise amplifier with simultaneous signal and noise power match at the input port.

Microscopic noise modeling and macroscopic noise models: how good a connection? [FETs

Based on the active line concept, a novel approach for the calculation of the high frequency noise performance of field effect transistors (FET) is proposed. By using a simple analytical theory, the FET small signal equivalent circuit as well as the macroscopic noise sources and their correlation are calculated for different two-port terminations. Values of the usual dimensionless noise parameters P, R, C, gate noise temperature T/sub g/ and drain noise temperature T/sub d/ are then given and discussed. By comparison with a more realistic numerical modeling of the noise performance, the validity of the analytical noise model is discussed. The validity of Pospieszalski's noise model and its relations with Pucel's one is emphasized.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>