Hermann Statz

Bio: Hermann Statz is an academic researcher from Raytheon. The author has contributed to research in topics: Flicker noise & Noise (radio). The author has an hindex of 12, co-authored 22 publications receiving 1367 citations.

GaAs FET device and circuit simulation in SPICE

Abstract: We have developed a GaAs FET model suitable for SPICE Circuit simulations. The dc equations are accurate to about 1 percent of the maximum drain current. A simple but accurate interpolation formula for drain current as a function of gate-to-source voltage connects the square-law behavior just above pinchoff and the square-root law for larger values of the drain current. The ac equations, with charge-storage elements, describe the variation of the gate-to-source and gate-to-drain capacitances as the drain-to-source voltage approaches zero and when this voltage becomes negative. Under normal operating conditions the gate-to-source capacitance is much larger than the gate-to-drain capacitance. At zero drain-to-source voltage both capacitances are about equal. For negative drain-to-source voltages the original source acts like a drain and vice versa. Consequently the normally large gate-to-source capacitance becomes small and acts like a gate-to-drain capacitance. In order to model these effect it is necessary to realize that, contrary to conventional SPICE usage, there are no separate gate-to-source and gate-to-drain charges, but that there is only one gate Charge which is a function of gate-to-source and gate-to-drain voltages. The present treatment Of these capacitances permits simulations-in which the drain-to-source voltage reverses polarity, as occurs in pass-gate circuits.

Signal and Noise Properties of Gallium Arsenide Microwave Field-Effect-Transistors

Abstract: Publisher Summary This chapter examines the signal and noise properties of gallium arsenide (GaAs) microwave field-effect transistors (FET) High frequency gallium arsenide field-effect transistors (GaAs FETs) have demonstrated remarkably low noise figures and high power gains at microwave frequencies A practical microwave GaAs FET is usually fabricated by deposition or diffusion of source, gate, and drain contacts on the surface of an appropriately doped thin epitaxial n-type layer This layer, in turn, is grown on a semi-insulating wafer by either a vapor or liquid epitaxial technique The apparent minor role played by the negative resistance region in practical short-gate FETs suggests that radiofrequency instabilities due to this region, if they exist, occur at frequencies far above the normal frequency regime of microwave FETs The small-signal equivalent circuit of the FET, valid up to moderately high frequencies is elaborated It is found that noise in a microwave GaAs FET is produced both by sources intrinsic to the device and by thermal sources associated with the parasitic resistances

Noise characteristics of gallium arsenide field-effect transistors

Abstract: Small signal and noise characteristics for GaAs field-effect transistors are derived with the saturated drift velocity of the carriers underneath the gate taken into account. The noise contributed by the saturated carriers is nonnegligible and in most cases, exceeds the noise generated by the unsaturated region. Parasitic elements contribute importantly by preventing the full cancellation of the correlated noise of the intrinsic transistor and by adding their own Johnson noise. The theory predicts the experimentally observed trend of noise figure dependence on drain current and on source-to-drain voltage. The present theory doesnot take into account the effects of a possible short negative resistance region underneath the gate.

The Multioscillator Ring Laser Gyroscope

Abstract: The multioscillator (or four-frequency) ring laser gyroscope is discussed from both a theoretical and a practical point of view. Fundamentals of device operation are presented, important nonideal behaviors (error sources) are discussed and analyzed from first principles, typical multioscillator gyroscopes are described, and samples of representative data from developmental instruments in our laboratories are reviewed. A key to the development of practical multioscillator instruments has been the introduction of nonplanar ring resonators. The theoretical formalisms (geometric and wave optic) necessary for understanding the properties of nonplanar ring resonators, and nonplanar gyroscopes, are derived and discussed in detail. Much of the material presented is new.

Noise in gallium arsenide avalanche Read diodes

Abstract: The noise and signal properties of Read-type avalanche diodes under large-signal levels are examined. In contrast to most other previous theories, we include the saturation current in the equations rigorously from the beginning. We find that the noise performance is a strong function of the saturation current such that high saturation currents lead to lower noise performance. We compare the findings of our model with measurements on two very different Read-type avalanche diodes with a low-high-low profile. In agreement with theory, the lower noise diode has a higher saturation current. We also find experimentally that the noise measure of the diodes used as oscillators decreases with increasing power output. This feature is explained by the rising reverse saturation current with temperature which in some diodes more than compensates the normally increasing noise measure with power output.

A Review of GaN on SiC High Electron-Mobility Power Transistors and MMICs

Abstract: Gallium-nitride power transistor (GaN HEMT) and integrated circuit technologies have matured dramatically over the last few years, and many hundreds of thousands of devices have been manufactured and fielded in applications ranging from pulsed radars and counter-IED jammers to CATV modules and fourth-generation infrastructure base-stations. GaN HEMT devices, exhibiting high power densities coupled with high breakdown voltages, have opened up the possibilities for highly efficient power amplifiers (PAs) exploiting the principles of waveform engineered designs. This paper summarizes the unique advantages of GaN HEMTs compared to other power transistor technologies, with examples of where such features have been exploited. Since RF power densities of GaN HEMTs are many times higher than other technologies, much attention has also been given to thermal management-examples of both commercial “off-the-shelf” packaging as well as custom heat-sinks are described. The very desirable feature of having accurate large-signal models for both discrete transistors and monolithic microwave integrated circuit foundry are emphasized with a number of circuit design examples. GaN HEMT technology has been a major enabler for both very broadband high-PAs and very high-efficiency designs. This paper describes examples of broadband amplifiers, as well as several of the main areas of high-efficiency amplifier design-notably Class-D, Class-E, Class-F, and Class-J approaches, Doherty PAs, envelope-tracking techniques, and Chireix outphasing.

Modeling of noise parameters of MESFETs and MODFETs and their frequency and temperature dependence

Abstract: A simple noise model of a microwave MESFET (MODFET, HEMT, etc.) is described and verified at room and cryogenic temperatures. Closed-form expressions for the minimum noise temperature, the optimum generator impedance, the noise conductance, and the generator-impedance-minimizing noise measure are given in terms of the frequency, the elements of a FET equivalent circuit, and the equivalent temperatures of intrinsic gate resistance and drain conductance to be determined from noise measurements. These equivalent temperatures are demonstrated in the case of a Fujitsu FHR01FH MODFET to be independent of frequency in the frequency range in which 1/f noise is negligible. Thus, the model allows prediction of noise parameters for a broad frequency range from a single frequency noise parameter measurement. The relationships between this approach and other relevant studies are established. >

GaAs FET device and circuit simulation in SPICE

Abstract: We have developed a GaAs FET model suitable for SPICE Circuit simulations. The dc equations are accurate to about 1 percent of the maximum drain current. A simple but accurate interpolation formula for drain current as a function of gate-to-source voltage connects the square-law behavior just above pinchoff and the square-root law for larger values of the drain current. The ac equations, with charge-storage elements, describe the variation of the gate-to-source and gate-to-drain capacitances as the drain-to-source voltage approaches zero and when this voltage becomes negative. Under normal operating conditions the gate-to-source capacitance is much larger than the gate-to-drain capacitance. At zero drain-to-source voltage both capacitances are about equal. For negative drain-to-source voltages the original source acts like a drain and vice versa. Consequently the normally large gate-to-source capacitance becomes small and acts like a gate-to-drain capacitance. In order to model these effect it is necessary to realize that, contrary to conventional SPICE usage, there are no separate gate-to-source and gate-to-drain charges, but that there is only one gate Charge which is a function of gate-to-source and gate-to-drain voltages. The present treatment Of these capacitances permits simulations-in which the drain-to-source voltage reverses polarity, as occurs in pass-gate circuits.

A new empirical nonlinear model for HEMT and MESFET devices

Abstract: A large-signal model for HEMTs and MESFETs, capable of modeling the current-voltage characteristic and its derivatives, including the characteristic transconductance peak, gate-source and gate-drain capacitances, is proposed. Model parameter extraction is straightforward and is demonstrated for different submicron gate-length HEMT devices including different delta -doped pseudomorphic HEMTs on GaAs and lattice matched to InP, and a commercially available MESFET. Measured and modeled DC and S-parameters are compared and found to coincide well. >

Signal and Noise Properties of Gallium Arsenide Microwave Field-Effect-Transistors

Abstract: Publisher Summary This chapter examines the signal and noise properties of gallium arsenide (GaAs) microwave field-effect transistors (FET) High frequency gallium arsenide field-effect transistors (GaAs FETs) have demonstrated remarkably low noise figures and high power gains at microwave frequencies A practical microwave GaAs FET is usually fabricated by deposition or diffusion of source, gate, and drain contacts on the surface of an appropriately doped thin epitaxial n-type layer This layer, in turn, is grown on a semi-insulating wafer by either a vapor or liquid epitaxial technique The apparent minor role played by the negative resistance region in practical short-gate FETs suggests that radiofrequency instabilities due to this region, if they exist, occur at frequencies far above the normal frequency regime of microwave FETs The small-signal equivalent circuit of the FET, valid up to moderately high frequencies is elaborated It is found that noise in a microwave GaAs FET is produced both by sources intrinsic to the device and by thermal sources associated with the parasitic resistances