This paper uses a Monte Carlo simulation program to explore various aspects of uncertainties associated with the measurement of the noise parameters of transistors on wafers.The dependence of the noise-parameter uncertainties on the different input uncertainties is investigated in detail.Other issues that are considered include the effect of probe losses, the importance (or not) of including input terminations with reflection coefficients as near as possible to the edge of the Smith chart, improvements due to inclusion of an input termination with noise temperature well below ambient, and the effect of including a "reverse" measurement.We also briefly consider the case of well-matched amplifiers on wafers.

A previously developed simulator for noise-parameter measurements has been used in an extensive investigation and comparison of different measurement strategies for measuring the noise parameters of low-noise amplifiers (LNAs). This paper summarizes the methodology and reports the salient results of that investigation. The simulator is based on a Monte Carlo program for noise-parameter uncertainties and enables us to compare the uncertainties (both type A and type B) obtained with a given set of input terminations. We focus on results that do not depend (or depend only weakly) on details of the device under test (DUT). One noteworthy result is the marked improvement in the noise-parameter measurement uncertainties when a matched, cold (i.e., well below ambient noise temperature) source is included in the set of input terminations.

This paper provides an overview of the use of noise parameters as a numerical model to represent the noise characteristics of transistors, particularly in the context of a Monte Carlo evaluation of the uncertainties in noise-parameter measurements. The Monte Carlo also relies on a numerical model of the measurement process, in order to generate simulated measurement results, and this numerical model is also reviewed. Copyright (c) 2014 John Wiley & Sons, Ltd.

Methods for measuring the noise parameters of amplifiers and on‐wafer transistors are reviewed. After some preliminary background information and conventions are presented, noise parameters are defined and the most common measurement strategies are presented, both for packaged amplifiers and for on‐wafer transistors (or amplifiers). The uncertainty analysis for such measurements is reviewed, and check and verification methods are presented.

We present a geometric error model associated with calibration-target misalignment in passive microwave remote-sensing systems. The developed analytic formulation is universally applicable to both lateral and rotational misalignment conditions. Numerical simulations are performed on two practical blackbody targets of different sizes used as radiation references for passive microwave remote sensing. The significance of this work is to furnish a framework of uncertainty analysis due to target misalignment and to provide a reference for alignment requirements based on passive radiometer measurement sensitivity.

We report measurements and uncertainty analysis on a cryogenic low-noise amplifier (LNA) with a very low noise temperature (NT), among the lowest noise performances reported at microwave frequencies. The LNA consists of three stages of InP high electron mobility transistors with a gate length of 130 nm. It exhibits about 44 dB gain and less than 2 K average NT in the operational band of 4 GHz to 8 GHz. A detailed uncertainty analysis is outlined to evaluate a variety of error sources in the measurement. The calculated uncertainty shows as low as 0.1 dB on the measured gain of about 44 dB and 0.18 K on the measured NT of 1.65 K, indicating excellent measurement accuracy. A breakdown of the uncertainty components helps identify the major causes of the overall uncertainty and enlightens us about how to further improve accuracy. It is important to know the actual physical temperature of the passive termination that is used as a cryogenic noise source in experiments. Due to its large temperature gradients, the commercial matched load is replaced by a custom-made attenuator that is isothermal and consequently provides reliable NT measurements of the LNA. The precision measurement technique developed at the National Institute of Standards and Technology is independent from the manufacturers' characterization method. This study marks the first time that such a low NT from a cryogenic LNA is verified independently with such a low uncertainty.

We compare three methods of quantifying illumination efficiency (IE). The ratio IE describes the contribution of energy emitted from a blackbody target to the total energy measured at an antenna aperture in a free-space microwave calibration target radiometric measurement. Measurements are compared at three frequencies: 18 GHz, 22.5 GHz, and 26 GHz. An antenna pattern integration method is compared with a recently developed target-temperature fitting method. These two experimental approaches are also compared to a computational antenna pattern simulation. Results show that the simulation agrees with the experimental fitting method more closely at far-field distances, whereas the antenna pattern integration and experimental fitting method agree at closer distances.

We describe and demonstrate a standard radiometer for making microwave brightness-temperature measurements that are traceable to fundamental noise standards. The standard radiometer is based on a National Institute of Standards and Technology (NIST) waveguide radiometer for 18-26.5 GHz, fitted with an antenna to measure radiated power. The fraction of the antenna pattern subtended by the radiating target is determined by anechoic-chamber measurements in which we vary the temperature of the target and measure the received power. Sample measurement results with uncertainties are presented. The typical standard uncertainty for a brightness temperature of around 340 K is about 1 K. The approach should be extendable to other waveguide bands where NIST has radiometers and standards.

We report our recent progress toward the development of microwave brightness-temperature (BT) standards. As one of the crucial parameters, the target illumination efficiency (IE) was traditionally determined from the relative antenna pattern. We propose a measurement technique to extract the target IE solely by the use of passive radiometric measurements for characterizing the BT of the blackbody radiator. Such a technique allows us to skip the complexities that are often encountered during the measurement and calculation of the antenna pattern. Taking advantage of the variable heating capability available on most blackbody targets, we varied the temperature of a heated blackbody target and ran a series of radiometric measurements when the target was separated at different distances away from the the antenna with the radiometer operating at a few frequencies. Our experimental results show excellent measurement accuracy on the IE, with uncertainty of about 1% at close separation distance between the antenna and the target. We further measured and computed the BT of the blackbody target at the locations where we had measured the extracted IE. The BT was slightly lower than the physical temperature of the target and exhibited 0.7 K to about 1 K uncertainty when the target was located no more than 1 m away from the antenna. A measurement uncertainty of 1 K already meets the accuracy requirements of some climate variables, and such results reflect a significant step toward the establishment of BT standards at microwave frequencies.

We report on the characterization of blackbody target reflections as part of the recent progress on the development of brightness temperature standards for microwave remote sensing at the National Institute of Standards and Technology. The very low reflections from the blackbody targets used in airborne or satellite remote-sensing systems present challenges on how to extract reflection coefficients from the measurements. A full calibration technique was developed for this study by use of a flat aluminum plate used as a known standard in combination with measurements of the empty anechoic chamber. The theoretical basis and measurement procedures are presented. Calibration results validate the method by showing its independence from measurement hardware and conditions. A comparison between the theoretical prediction of reflection coefficients of a free-standing dielectric slab with well documented physical parameters and the de-embedded reflection coefficients from experiments confirms good calibration accuracy. The specific blackbody target used in this study shows well matched properties with a power reflectivity below -40 dB over the entire measurement band (18 GHz to 26 GHz).

We report on the characterization of blackbody target reflections as part of the recent progress on the development of brightness temperature standards for microwave remote sensing at the National Institute of Standards and Technology. The very low reflections from the blackbody targets used in airborne or satellite remote sensing systems present challenges on how to extract reflection coefficients from the measurements. A full calibration technique is developed for this study by the use of a flat aluminum plate used as a known standard in combination with measurements of the empty anechoic chamber. The theoretical basis and measurement procedures, along with the uncertainty analysis, are presented. Calibration results validate the method by showing its independence from measurement hardware and conditions. A comparison between the theoretical prediction of reflection coefficients of a free-standing dielectric slab with well-documented physical parameters and the de-embedded reflection coefficients from experiments confirms good calibration accuracy. The specific blackbody target used in this paper shows well-matched properties with a power reflectivity below -40 dB over the entire measurement band (18 to 26 GHz).

We propose and implement verification methods for measurements of the noise parameters of amplifiers and transistors. Because the verification rests on the comparison of different measurement results, it also serves as a test of the uncertainties. The verification process consists of first measuring separately both a passive two-port device and the amplifier or transistor of interest [the device under test (DUT)] and then measuring the tandem configuration of the passive device plus the DUT. The results of the measurements on the tandem configuration are compared to the results predicted based on the noise parameters and scattering parameters of the two individual components. In this paper, we describe the method, discuss the uncertainty analysis, and present measurement results demonstrating the application of the method using a mismatched transmission line as the passive device. We also present simulation results demonstrating the ability of the method to detect measurement errors.

We report a miniaturized phase shifter operating in the frequency range from 5 to 7 GHz for noise‐parameter extraction. Such a tunable solid‐state unit represents a significant reduction in the size and mass as a source‐pull component, compared to its mechanical counterparts. It provides adequate impedance coverage, ultra‐fast response, as well as high repeatability, across the designed region. A packaged low‐noise amplifier was measured at integer frequencies by use of the phase shifter on the NIST NFRad system. The measured results exhibited good accuracy. The combined uncertainties (Type‐A and Type‐B) are below 6% for both the minimum noise temperature and the magnitude of the optimum input reflection coefficient. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2600–2603, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25532

We have presented a close look at effects of order hf/kT in noise measurements and in the definition of noise quantities-noise temperature, noise figure, etc. Given the perennial push to higher frequency, lower noise, and smaller uncertainty, such effects are becoming significant in an increasing number of applications, and especially in radio astronomy where the noise temperature of a modern receiver can be within a factor of a few of the quantum limit. In particular, we have discussed issues arising from the definition of noise temperature and the treatment of contributions from vacuum fluctuations. There is more than one correct way to deal with these effects, but it is important to be consistent in one's approach and not to mix methods.

We report the results of an international comparison of measurements of radio frequency voltage in the frequency range 1 MHz to 1 GHz. This comparison was performed as a "Key Comparison" under the auspices of the Consultative Committee for Electricity and Magnetism (CCEM) of the International Committee for Weights and Measures (CIPM). Participating laboratories were the designated National Metrology Institutes (NMIs) for their respective countries.

We report on the characterization of blackbody reflections as a part of the recent progress on the development of brightness standards for microwave remote sensing at National Institute of Standards and Technology (NIST). Three blackbody targets at variable temperatures used for airborne and/or satellite systems along with an aluminum plate were measured in terms of their reflection coefficients by horn antennas in connection with a vector network analyzer (VNA) in the WR-42 waveguide band. Precision measurements of reflection are needed for blackbody emissivity computation to check against the brightness temperature measurement of blackbody targets. All experiments were conducted in two distance ranges by free-space methods in an anechoic chamber. Preliminary results show negligible reflections from the calibration targets, indicating near ideal blackbody characteristics in the measured frequency range.

A brief summary is presented for the uncertainty analysis for measurements of noise parameters of amplifiers and transistors, in both connectorized (coaxial) and on-wafer environments. We treat both the X-parameters, which are based on the wave representation of the noise correlation matrix, and the traditional IEEE noise parameters.