1/f noise in semiconductors, semiconductor devices, and collision-free devices (like vacuum tubes) is presented from a unified point of view, using an extended version of the F.N. Hooge equation (Physica, vol. 83b, p.9, 1976), which is generalized to all collision-dominated systems involving mobility, diffusion, and cross-section fluctuations. It also applies to collision-free processes involving vacuum tubes, Schottky barrier diodes operating in the thermionic mode, and in devices such as p-i-n diodes in which collision processes are not the determining factor. A generalized schematic is given for expressing the noise spectrum S/sub 1/(f) in the external circuit in terms of distributed noise sources of the nonuniform devices in terms of alpha /sub H/, so the latter can be determined from the former. It is then found that the Hooge parameter. alpha /sub H/ introduced by this equation can be used as a general measure of the noisiness of a system or device. Several cases in which the noise does not obey the quantum 1/f noise theory are discussed. Measurements on many different devices are examined, and an attempt is made to correlate measured values of the Hooge parameter with the values calculated from P.H. Handel's quantum theory of 1/f noise (1975, 1980). >

Unified presentation of 1/f noise in electron devices: fundamental 1/f noise sources

In an exemplary embodiment, a phased array antenna comprises multiple subcircuits in communication with multiple radiating elements. The radio frequency signals are adjusted for both polarization control and beam steering. In a receive embodiment, multiple RF signals are received and combined into at least one receive beam output. In a transmit embodiment, at least one transmit beam input is divided and transmitted through multiple radiating elements. In an exemplary embodiment, the phased array antenna provides multi-beam formation over multiple operating frequency bands. The wideband nature of the active components allows for operation over multiple frequency bands simultaneously. Furthermore, the antenna polarization may be static or dynamically controlled at the subarray or radiating element level.

Multi-beam active phased array architecture

Theoretical and experimental work for the performance of GaAs MESFET's under illumination from light of photon energy greater than the bandgap of the semiconductor is described. A simple model to estimate the effects of light on the dc and RF properties of MESFET'S is presented. Photoconductive and photovoltaic effects in the active channel and substrate are considered to predict the change in the dc equivalent circuit parameters of the FET, and from these the new Y- and S-parameters under illumination are calculated. Comparisons with the measured S-parameter's without and under illumination show very close agreement. Optical techniques can he used to control the gain of an FET amplifier and the frequency of an FET oscillator. Experimental results are presented showing that the gain of amplifiers can be varied up to around 20 dB and that the frequency of oscillators can be varied (tuning) around 10 percent when the optical absorbed power in the active region of the FET is varied by a few microwatts. When the laser beam is amplitude-modulated to a frequency close to the free-running FET oscillation frequency, optical injection locking can occur. An analytical expression to estimate the locking range is presented. This shows a fair agreement with the experiments. Some suggestions to improve the optical locking range are presented.

Optical Control of GaAs MESFET's

We present a computational and experimental study of a novel terahertz (THz) device resulting from hybridization of metamaterials with pseudomorphic high electron mobility transistors (HEMTs), fabricated in a commercial gallium arsenide (GaAs) process. Monolithic integration of transistors into each unit cell permits modulation at the metamaterial resonant frequency of 0.46 THz. Characterization is performed using a THz time-domain spectrometer (THz-TDS) and we demonstrate switching values over 30%, and THz modulation at frequencies up to 10 megahertz (MHz). Our results demonstrate the viability of incorporating metamaterials into mature semiconductor technologies and establish a new path toward achieving electrically tunable THz devices.

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High speed terahertz modulation from metamaterials with embedded high electron mobility transistors

The subject of this disclosure may relate generally to systems, devices, and methods using interleaved waveguide elements. Specifically, systems, devices, and methods using a dual-polarized broadband, multi-frequency interleaved waveguide antenna aperture are presented. In one exemplary embodiment, a first plurality of waveguide elements are configured to communicate in a first frequency band. In this exemplary embodiment, a second plurality of waveguide elements are configured to communicate in a second frequency band. In one exemplary embodiment the first plurality of waveguide elements and the second plurality of waveguide elements are integrally coupled to a printed circuit board.

Dual-polarized, multi-band, full duplex, interleaved waveguide antenna aperture

The influence of the algorithm used for noise parameter fitting on the accuracy of the microwave noise parameter measurements is investigated. Five different commonly used algorithms are compared by a statistical analysis including instrument accuracy specifications. Some of these algorithms are found to be more efficient in terms of available accuracy and computer time. The best predicted available accuracies reported betwen 4 and 20 GHz for each noise parameter compare well with observed accuracies on noise parameter measurements performed with a dedicated test set on a noise standard made of a passive two-port. The accuracy on minimum noise figure is found to be 0.1 dB maximum. >

Evaluation of noise parameter extraction methods

Noise properties of AlGaAs/InGaAs/GaAs pseudomorphic HEMTs (PHEMTs) have been investigated simultaneously in the low and intermediate frequency range (10 Hz to 150 MHz) and in the microwave range (4 to 18 GHz) and compared to the noise of more classical devices such as MESFETs and GaAlAs/GaAs HEMTs. Unlike the other commercially available devices, PHEMTs exhibit the unique capability of providing simultaneously state-of-the-art microwave noise performance and a reasonable low-frequency excess noise. >

Noise in AlGaAs/InGaAs/GaAs pseudomorphic HEMTs from 10 Hz to 18 GHz

It is shown theoretically and experimentally that the variations of the d.c. and dynamic properties in a GaAs f.e.t. when a light beam strikes the transistor's gate can be accounted for by an appropriate change in the gate-junction equivalent built-in voltage. A simple relationship connects this change with the variations of the light intensity.

Light-induced effects in GaAs f.e.t.s

A 6-GHz low power SiGe direct digital synthesizer (DDS) is reported. This letter discusses the BiCMOS design improvements used for the phase accumulator and the phase-to-amplitude conversion in order to achieve higher speed operation and lower power consumption compared to existing DDS. The phase accumulator is based on a three-level BiCMOS logic, and the phase-to-amplitude conversion is completed through a bipolar differential pair. The circuit has been processed in a BiCMOS SiGe:C 0.25 mum technology. The power consumption is 308 mW and it operates from a 2.8 V supply. The chip core area is 1 mm2.

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A 6-GHz Low-Power BiCMOS SiGe:C 0.25 $\mu$ m Direct Digital Synthesizer

An experimental setup, based on current/voltage conversion through transimpedance amplifiers (TAs), has been implemented for the direct full low-frequency noise (LFN) characterization of Si/SiGe heterojunction bipolar transistors (HBTs) in terms of base and collector short-circuit current noise sources. This setup performs a full characterization, as it measures simultaneously the two noise current sources and their correlation, thanks to an original technique based on the specific properties of a specially designed buffer amplifier using a low-noise common-base bipolar transistor (CB BJT). By means of translation formulae, the obtained measurements are compared with those carried out with a multi-impedance technique. They show a good agreement both for the noise sources spectral densities and for their correlation. The TA-based setup provides enhanced capabilities in terms of measurement speed and remote control potentialities.

J. Graffeuil

Papers

Evaluation of noise parameter extraction methods

Noise in AlGaAs/InGaAs/GaAs pseudomorphic HEMTs from 10 Hz to 18 GHz

Light-induced effects in GaAs f.e.t.s

A 6-GHz Low-Power BiCMOS SiGe:C 0.25 $\mu$ m Direct Digital Synthesizer

Transimpedance amplifier-based full low-frequency noise characterization setup for Si/SiGe HBTs