Jörgen Stenarson

Cryogenic wide-band ultra-low-noise IF amplifiers operating at ultra-low DC power

This paper describes cryogenic broad-band amplifiers with very low power consumption and very low noise for the 4-8-GHz frequency range. At room temperature, the two-stage InP-based amplifier has a gain of 27 dB and a noise temperature of 31 K with a power consumption of 14.4 mW per stage, including bias circuitry. When cooled to 15 K, an input noise temperature of 1.4 K is obtained at 5.7 mW per stage. At 0.51 mW per stage, the input noise increases to 2.4 K. The noise measurements have been repeated at different laboratories using different methods and are found consistent.

An empirical table-based FET model

A new large signal field effect transistor (FET) model combining empirical and table based models was developed and investigated experimentally. The Chalmers empirical model was used as a spline function for the table based model. Combining models improves accuracy and simplifies and speeds extraction. The procedure can be applied for other types of devices.

An empirical-table based FET model

A new large signal field effect transistor (FET) model combining empirical and table based models was developed and investigated experimentally. The Chalmers empirical model was used as a spline function for the table based model. Combining models improves accuracy and simplifies and speeds extraction. The procedure can be applied for other types of devices.

An in-circuit noncontacting measurement method for S-parameters and power in planar circuits

A method for measuring the reflection coefficient and absolute power in the propagating waves from a circuit embedded in a planar circuit environment is presented. The method utilizes a pair of inductive and capacitive probes. The standard one-port vector-network-analyzer calibration is extended to allow the measurement of power in the forward and backward waves. Experimental results are presented for measurements between 700 MHz and 20 GHz. Good agreement between the new noncontacting method and a standard coaxial measurement method is demonstrated up to 12 GHz for power and up to 14 GHz for the reflection coefficient. The method is useful for in-circuit testing of open transmission-line structures, e.g., microstrip.

On the performance of low-noise low-DC-power-consumption cryogenic amplifiers

The performance of broad-band low-noise low-dc-power-consumption cryogenic amplifiers have been studied in detail with emphasis on minimizing the power consumption and optimizing the amplifier performance at cryogenic temperature. A general approach is presented for the modeling and amplifier design, which helps in minimizing the power consumption and optimizing the performance of the amplifier. A noise temperature below 9 K and 22-dB gain was experimentally obtained in the frequency range of 4-8 GHz with a total power consumption of 4 mW with commercial GaAs transistors.

A new extraction method for the two-parameter FET temperature noise model

This paper presents a direct extraction method for the associated noise temperatures T/sub d/ and T/sub g/ in the field-effect transistor (FET) temperature noise model. The method is related to nodal analysis of circuits. T/sub d/ and T/sub g/ are extracted from the small-signal model parameters and the noise parameters of the device. It is also theoretically shown that there exist source admittances that cancel the thermal noise contribution at the output from either T/sub d/ or T/sub g/ in the model. Finally, a commercially available GaAs pseudomorphic high electron-mobility transistor (pHEMT) is measured and modeled for a wide range of bias points. Comparisons between measured and modeled noise parameters are presented in the 2-26 GHz frequency range.

Noncontacting measurement of reflection coefficient and power in planar circuits up to 40 GHz

This paper describes the use of loop-coupler probes for noncontacting measurement of power and reflection coefficient in microstrip circuits up to 40 GHz. The inherent directivity of the loop-coupler probe makes it suitable for use with scalar measuring instruments such as power meters and spectrum analyzers. The probe coupling and directivity and their sensitivity to probe positioning errors are investigated. The results are summarized in a simple uncertainty budget. Measurements of reflection coefficient with a vector network analyzer are also presented and verified by coaxially contacting measurements.

Measurement Uncertainty in Power Splitter Effective Source Match

The authors present an uncertainty calculation together with a technique to assess the residual error when calibrating the effective source match of power splitters. The technique is applied to the Juroshek method, which is the most convenient way of measuring the effective source match. The technique uses an airline as impedance reference and is similar to the ripple technique used when evaluating the residual errors in vector network analyzers

An evaluation of three simple scalable MIM capacitor models

This paper presents an evaluation of three different scalable metal-insulator-metal capacitor models for use in monolithic-microwave integrated-circuit design. The models, including one previously unpublished, are based on transmission-line theory and are easily scalable using only physical dimensions and constants. Comparisons to measured data for several device sizes, up to 45deg in electrical length, show that the three models exhibit similar performance, with a mean deviation between models and S11 measurements that is less than 3%

A general parameter-extraction method for transistor noise models

A new general direct extraction procedure for transistor noise models including two correlated noise sources is developed. The extraction procedure is demonstrated for a Silicon Carbide (SiC) Metal Semiconductor Field Effect Transistor (MESFET). The extracted model shows good agreement to measured noise parameters.