Low Noise

An applications-oriented review of optical parametric amplifiers in fiber communications is presented. The emphasis is on parametric amplifiers in general and single pumped parametric amplifiers in particular. While a theoretical framework based on highly efficient four-photon mixing is provided, the focus is on the intriguing applications enabled by the parametric gain, such as all-optical signal sampling, time-demultiplexing, pulse generation, and wavelength conversion. As these amplifiers offer high gain and low noise at arbitrary wavelengths with proper fiber design and pump wavelength allocation, they are also candidate enablers to increase overall wavelength-division-multiplexing system capacities similar to the more well-known Raman amplifiers. Similarities and distinctions between Raman and parametric amplifiers will also be addressed. Since the first fiber-based parametric amplifier experiments providing net continuous-wave gain in the for the optical fiber communication applications interesting 1.5-m region were only conducted about two years ago, there is reason to believe that substantial progress may be made in the future, perhaps involving "holey fibers" to further enhance the nonlinearity and thus the gain. This together with the emergence of practical and inexpensive high-power pump lasers may in many cases prove fiber-based parametric amplifiers to be a desired implementation in optical communication systems.

A complete analysis of low-noise 0.1 m gate AlInAs/GaInAs HEMT's has been performed by using a semiclassical Monte Carlo simulation. The validity of the model has been checked through the comparison of the simulated results with static, dynamic and noise experimental measurements of real HEMTs. In order to reproduce the experimental results, we have included in the model some important real effects such as degeneracy, surface charges, T-shape of the gate, presence of dielectrics and contact resistances. Moreover, the extrinsic parameters of the devices have been added to the usual intrinsic small-signal equivalent circuit, thus allowing the calculation of the real noise of the HEMTs (characterized using the extrinsic minimum noise . In this way, we make possible not only the comparison with the experimental noise results, but also the analysis of the influence of the parasitic elements, the device width or the number of gate fingers on the noise of the HEMTs. The reliability of the simulator allows us to realize "computer experiments" which will make faster and cheaper the optimization process of the device design. for his work on the modeling and the characterization of MES-FETs and HEMTs. In 1977, he joined the Centre Hyperfrequences et Semiconducteurs, University of Lille, France. He is now Professor of electronics at the University of Lille. His main research interests are concerned with the modeling, the realization and the characterization of low noise devices for application in the centimeter and millimeter wave ranges.

New advances in hot electron bolometer (HEB) mixers have recently resulted in record-low receiver noise temperatures at terahertz frequencies. We have developed quasi-optically coupled NbN HEB mixers and measured noise temperatures up to 2.24 THz, as described in this paper. We project the anticipated future performance of such receivers to have even lower noise temperature and local-oscillator power requirement as well as wider gain and noise bandwidths. We introduce a proposal for integrated focal plane arrays of HEB mixers that will further increase the detection speed of terahertz systems.

A large area, charge-couple-device (CCD) based fiberoptic taper array detector (APS-1) has been installed at the insertion-device beamline of the Structural Biology Center at the ANL Advanced Photon Source. The detector is used in protein crystallography diffraction experiments, where the objective is to measure the position and intensity of X-ray Bragg peaks in diffraction images. Large imaging area, very high spatial resolution, high X-ray sensitivity, good detective quantum efficiency, low noise, wide dynamic range, excellent stability and short readout time are all fundamental requirements in this application. The APS-1 detector converts the two-dimensional X-ray patterns to a visible light images by a thin layer of Xray sensitive phosphor. The phosphor coating is directly deposited on the large ends of nine fiberoptic tapers arranged in a 3x3 array. Nine; thermoelectrically cooled 1024 x 1024 pixel CCD's image the patterns, demagnified by the tapers. After geometrical and uniformity corrections, the nine areas give a continuous image of the detector face with virtually no gaps between the individual tapers. The 18 parallel analog signal-processing channels and analog-to-digital converters assure short readout time and low readout noise.

The sub-millimeter radiometers of the Herschel mission have very stringent requirements. The scientific goals require an instantaneous bandwidth of four GHz with very low noise, flat gain and low power dissipation. Short-term gain stability of the amplifier is important, because gain fluctuations could limit the sensitivity of the instrument. Besides, a highly reliable, low weight unit is required to be compatible with the space instrumentation standards. The amplifiers will be used in conjunction with HEB and SIS mixers in all 7 channels of the instrument. This paper describes the design, the special construction techniques and the results of the amplifiers built by Centro Astronómico de Yebes for the development model of the Herschel Heterodyne Instrument. The average noise temperature obtained in the 4-8 GHz band is 3.5 K, with a gain of 27 ±1.1 dB at an ambient temperature of 15 K and keeping the total power dissipation below the allowed 4 mW. Normalized gain fluctuations were carefully measured, being lower than 1.5·10 -4 Hz -1/2 @ 1 Hz. Space qualification of the design is in progress.

The paper presents opportunities of cavity enhanced absorption spectroscopy technique application in nitrogen oxides (NO x ) detection. In this method the concentration of an absorbing gas is determined by measure of decay time of the light pulse trapped in an optical cavity. The measurements are not sensitive to fluctuation of both laser power and photodetector sensitivity. The cavity enhanced absorption spectroscopy technique is a modification of cavity ring down spectroscopy technique where the off-axis adjustment of the resonator is used. NO x detection is carried out in the visible and infrared range. The signal is registered with a developed low noise photoreceiver. Features of the presented sensor show that it is possible to build a portable trace gases sensor. Its sensitivity could be comparable with chemical detectors. Such a system has several advantages: relatively low price, small size and weight, and detection possibility of other gases.

Terahertz time-domain transmission spectroscopy was used to obtain the absorption coefficients and refractive indices of polycrystalline quartz, amorphous silica, Pyrex and BK7 glasses. The results were analyzed in terms of the power-law model of far-infrared absorption. Evidence of the Boson peak was seen in the absorption spectra. Relationships were observed between THz absorption and refractive indices on the one hand, and glass structure and properties on the other. THz TDS is demonstrated to be a useful tool in the study of far-infrared transmission properties of glasses, producing low-noise, high resolution measurements of absorption coefficients and refractive indices.

This paper presents a comprehensive comparison of three state-of-the-art heterojunction bipolar transistors (HBTs); the AlGaAs/GaAs HBT, the Si/SiGe HBT and the InGaAs/InP HBT. Our aim in this paper is to find the potentials and limitations of these devices and analyze them under common Figure of Merit (FOM) definitions as well as to make a meaningful comparison which is necessary for a technology choice especially in RF-circuit and system level applications such as power amplifier, low noise amplifier circuits and transceiver/receiver systems. Simulation of an HBT device with an HBT model instead of traditional BJT models is also presented for the AlGaAs/GaAs HBT. To the best of our knowledge, this work covers the most extensive FOM analysis for these devices such as I-V behavior, stability, power gain analysis, characteristic frequencies and minimum noise figure. DC and bias point simulations of the devices are performed using Agilent's ADS design tool and a comparison is given for a wide range of FOM specifications. Based on our literature survey and simulation results, we have concluded that GaAs based HBTs are suitable for high-power applications due to their high-breakdown voltages, SiGe based HBTs are promising for low noise applications due to their low noise figures and InP will be the choice if very high-data rates is of primary importance since InP based HBT transistors have superior material properties leading to Terahertz frequency operation.

In this paper, a fully passivated true Enhancementmode 110-nm metamorphic high-electron mobility transistor (E-MHEMT) on GaAs substrate with excellent dc and RF performance has been developed. By choosing an indium content of 40% for the AlInAs/GaInAs/AlInAs MHEMT, the difference between the Schottky-barrier height and the conductance band-offset (channel/barrier) of the device is enhanced compared with 53% indium devices lattice matched to an InP substrate. A true E-MHEMT is demonstrated with an extremely low leakage current, wide gate-voltage swing, and excellent dynamic performance. The threshold-voltage standard deviation is only 12 mV on four wafers. The device presents an excellent unity gain cutoff frequency of 204 GHz with state-of-the-art NF min = 0.69 dB and Gass = 10 dB at 30 GHz. This transistor is a good candidate for high-speed digital, high-frequency analog, or mixed applications, where the low noise, low-power consumption, and digital capabilities of this technology are distinct advantages.

Perpendicular recording has long been advocated as a means of achieving the highest areal densities. In particular, in the context of the 'superparamagnetic limit', perpendicular recording with a soft underlayer promises several key advantages. These advantages include a higher coercivity, thicker media that should permit smaller diameter grains and higher signal-to-noise ratio. Also, the sharper edge-writing will facilitate recording at very high track densities (lower bit aspect ratio). Recent demonstrations of the technology have shown densities comparable with the highest densities reported for longitudinal recording. This paper further examines the promise that perpendicular recording will deliver an increase in areal density two to eight times higher than that achievable with longitudinal recording. There are a number of outstanding issues but the key challenge is to create a low-noise medium with a coercivity that is high and is much larger than the remanent magnetization. r

Existing works on variational bayesian (VB) treatment for factor analysis (FA) model such as . Variational inference for Bayesian mixture of factor analysers. In Advances in neural information proceeding systems. Cambridge, MA: MIT Press; Nielsen, F. B. . Variational approach to factor analysis and related models. Master's thesis, The Institute of Informatics and Mathematical Modelling, Technical University of Denmark.] are found theoretically and empirically to suffer two problems: x penalize the model more heavily than BIC and y perform unsatisfactorily in low noise cases as redundant factors can not be effectively suppressed. A novel VB treatment is proposed in this paper to resolve the two problems and a simulation study is conducted to testify its improved performance over existing treatments.

We report on the experimental demonstration of strong quadrature EPR entanglement and squeezing at very low noise sideband frequencies produced by a single type-II, self-phase-locked, frequency degenerate optical parametric oscillator below threshold. The generated two-mode squeezed vacuum state is preserved for noise frequencies as low as 50 kHz. Designing simple setups able to generate non-classical states of light in the kHz regime is a key challenge for high sensitivity detection of ultra-weak physical effects such as gravitational wave or small beam displacement.

We have developed a novel analog front-end part of a wireless brain oxymeter receiver instrument based on near-infrared spectroreflectometry (NIRS). The NIRS receiver makes use of dynamic threshold transistors (DTMOS) for low voltage (1–V), low power and low noise enhancement. The design is composed of a transimpedance amplifier (TIA) and an operational transconductance amplifier (OTA). The OTA differential input pairs are in a class AB configuration, and uses DTMOS devices for input common-mode range enhancement. Post-layout simulations under a 5 pF load, using 0.18 µm CMOS technology results are, for the OTA, an input referred noise of 134 nV/√Hz at 1 kHz, and a power consumption of 16.7 µW without any extra noise reduction technique. Also, the TIA gives 208 pA/√Hz at 1 kHz, while having a power consumption of only 10.9 µW. The proposed analog front-end circuits have been used to implement a NIRS receiver instrument with improved ultra low-light level measurements, high resolution...

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Widely-tunable Sampled-Grating Distributed Bragg Reflector (SG-DBR) lasers with integrated Semiconductor Optical Amplifiers (SOAs) simultaneously exhibit high (20 mW CW) fiber-coupled output power, high (>40) side mode suppression ratio, low noise (below -140 dB/Hz RIN), low line-width (<5 MHz), and high reliability, across a 40 nm Cband tuning range.

In this paper, a high Q tunable 2nd order band-pass filter, working in the RF frequency range and designed in a II. ACTIVE INDUCTOR standard AMS 0.35pm CMOS technology, is proposed. The shows the topology of a CMOS active inductor [1-9] filter is based on three different stages that perform the input in its N-type and P-type versions. As well known, defining the and output impedance matching, the bandpass function and Ml input impedance relative to Vg and Igi as H(s) Vg Ig] and prevent instabilities; therefore, it is suitable for integrated * * * * -°*°f ront-end RF applications. Simulation results have shown a

We present a compact integrated fiber laser with more than 200 mW of output power. It combines polarized fiber output with very narrow linewidth of less than 2 kHz. The coherence length of the laser is measured to be longer than 5 km. The laser features high mode stability of less than 10 MHz over hours. The relative intensity noise (RIN) spectrum is dominated by a peak at the relaxation oscillation frequency and is shot-noise limited otherwise. The RIN peak at 1 MHz is reduced to 130 dB Hz by integrating a negative feedback circuit. In addition to thermal wavelength tuning, the laser frequency can be modulated at a bandwidth of up to 10 kHz via the piezoelectric effect.

Abstrac/-SAR surveys from separate passes show relative shifts of the ground wavcnu m ber spectra thaI depend on the local slope and the off-nadir angle. We discuss the exploitation of this spectral sllift for different app] ications: I) generation of "low noise" intcrferograms benefiting phase unwrapping, 2) generation of quick-look interferograms, 3) decorrelation redllction by means of tunable SAl{ systems (TINSAR), 1 4) range resolution enhancement, and 5) the combination of SAR data gathered by different platforms (airborne and satell ite) for a "long-lime coherence" sludy.

We consider the Kuramoto model of globally coupled phase oscillators with time-delayed interactions, that is subject to the Ornstein-Uhlenbeck (Gaussian) colored or the non-Gaussian colored noise. We investigate numerically the interplay between the influences of the finite correlation time of noise τ and the time delay τ d on the onset of the synchronization process. Both cases for identical and nonidentical oscillators had been considered. Among the obtained results for identical oscillators is a large increase of the synchronization threshold as a function of time delay for the colored non-Gaussian noise compared to the case of the colored Gaussian noise at low noise correlation time τ. However, the difference reduces remarkably for large noise correlation times. For the case of nonidentical oscillators, the incoherent state may become unstable around the maximum value of the threshold (as a function of time delay) even at lower coupling strength values in the presence of colored noise as compared to the noiseless case. We had studied the dependence of the critical value of the coupling strength (the threshold of synchronization) on given parameters of the stochastic Kuramoto model in great details and presented results for possible cases of colored Gaussian and non-Gaussian noises.

We report low noise multiplication region structures designed for avalanche photodiodes grown on InP substrates. By either implementing a single heterostructure or using a pseudograded structure in the multiplication region, better control of spatial distribution of impact-ionization for both injected and feedback carriers can be achieved; localization of the carrier impact ionization process has resulted in very low excess noise.

The experimental detection of capacitance variations with a resolution as low as few zeptoFarads (10 −21 F) is presented. This is achieved by means of a CMOS ultra-low-noise and wide-bandwidth current sensing circuit, coupled to a lock-in amplifier to perform capacitance and conductance measurements in a frequency range from DC to 1 MHz. The adoption of an integrated implementation, based on an original circuital topology, provides miniaturization and performance improvement. The mm-sized chip can be easily integrated in extremely compact sensing setups. Resolution limits are analyzed in detail and experimentally investigated by means of a mechanical fixture that converts micrometric linear displacement into sub-aF capacitance steps. The experimental results match the theoretical expectation down to a resolution of 5 zF rms (6 V at 100 kHz, with a 100 ms time constant). The achieved current resolution of 15 fA rms (at ∼ms time scale) and the tracking of 40 zF capacitance steps demonstrate how the proposed read-out circuit can serve as a versatile tool for the development of nanosensors.

A low noise constant current source used for measuring the 1/f noise in disordered systems in ohmic as well as non-ohmic regime is described. The source can supply low noise constant current starting from as low as 1 µA to a few tens of mA with a high voltage compliance limit of around 20 Volts. The constant current source has several stages which can work in a standalone manner or together to supply the desired value of load current. The noise contributed by the current source is very low in the entire current range. The fabrication of a low noise voltage preamplifier modified for bias dependent noise measurements and based on the existing design available in the MAT04 data sheet is also described.

The paper concerns Drag-Free and Attitude Control of the European satellite Gravity field and steady-state Ocean Circulation Explorer (GOCE) during the science phase. Design has followed Embedded Model Control, where a spacecraft/environment discrete-time model becomes the realtime control core and is interfaced to actuators and sensors via tuneable feedback laws. Drag-free control implies cancelling non-gravitational forces and all torques, leaving the satellite to free fall subject only to gravity. In addition, for reasons of science, the spacecraft must be carefully aligned to the local orbital frame, retrieved from range and rate of a Global Positioning System receiver. Accurate drag-free and attitude control requires proportional and low-noise thrusting, which in turn raises the problem of propellant saving. Six-axis drag-free control is driven by accurate acceleration measurements provided by the mission payload. Their angular components must be combined with the star-tracker attitude so as to compensate accelerometer drift. Simulated results are presented and discussed. he contributed to data reduction of the European astrometric mission Hipparcos. Technological studies in view of scientific and drag-free space missions, like Gaia and GOCE provided the opportunity of applying Embedded Model Control to drag-free satellites and to electro-optics. He contributed to the conception, design and implementation of the interferometric thrust-stand Nanobalance, capable of sub-micro-Newton accuracy. His research interests cover the entire field of control problems that are challenging because of complexity, uncertainty and precision.

Improving the of radio telescopes and ra- diometers and their associated receive subsystems translates into increasing the ground received signal-to-noise ratios. Therefore, low noise amplification with cooling operation is required. How- ever, the system designer must select an appropriate feedhorn antenna with low sidelobes and an adapted illumination at the edge of the reflector since the noise originated from the

The second harmonic induced voltage in the pick-up coil of a fluxgate magnetometer is generally used as a measure of the external Ž . magnetic field M.F. in applications where high stability and low noise are required. Fourth harmonic component advantages over the Ž . second harmonic, such as improved sensitivity, fundamentally at weak fields are reported in this paper. Moreover it was obtained that the fourth harmonic induced voltage linearity in open loop is greater than that of the second harmonic. q 1999 Elsevier Science S.A. All rights reserved.

The limits of the noise performance of detector readout front ends in CMOS technology have been studied. A theoretical minimal number of equivalent noise charge (ENC) that can be achieved by a CMOS technology is derived, taking both thermal noise and 1/f noise into account. Design criteria and techniques of CMOS readout front ends are presented so as to fully

High-power transmission capacity at low-energy losses, low noise emissions, high reliability, and ease of maintenance, as well as convenient cost-effectiveness, are required for industrial applications regarding variable electro-hydraulic supply systems. Only up-to-date principles regarding volumetrically controlled hydraulic energy using variable supply systems and appropriate control strategy have proven satisfactory for these requirements. The aim of the present work was to study the applicability of a low-priced drive concept using a speed-controlled induction motor in combination with a constant-displacement pump applied in a load-sensing control strategy. The suggested approach of the drive concept has been experimentally verified on a prototype of the drive. A hydraulic press-brake used for the machining of casting products in the automotive industry was taken into consideration.

This letter presents, for the first time, measured data on a Bragg reflection grating based fiber-optic prism true time delay processor for transmit/receive phased array beamforming. Measurements taken over a 3.5-GHz bandwidth demonstrates high resolution beamsteering and highly linear low-noise phase data. The system takes maximum advantage of component reuse and fully integrates the transmit and receive modes in one efficient hardware compressive topology.

A novel design of low noise amplifier for medical ultrasound transducers is described in this paper. Unlike conventional low noise preamplifiers, this design proposes a new circuit configuration which has electronically adjustable matching resistance that allows the preamplifier to be compatible with a variety of medical ultrasound transducers. The design employs current feedback operational amplifier to enhance the gain-bandwidth independence

Th e generation of femtosecond optical pulses 1 has opened up a range of applications from real-time monitoring of chemical reactions through to ultrahigh-bit-rate optical communications 2 , and has led to new concepts in femtosecond optical networking, signal processing and transmission. In fact, lasers operating at multigigahertz repetition rates are now becoming key components for high-capacity telecommunication systems, photonic switching devices, optical interconnects, clocks for very-large-scale integrated microprocessors and high-speed electro-optic sampling systems.

In the past two decades, imaging sensors and detectors have developed tremendously. This technology has found its way into a number of areas, such as space missions, synchrotron light sources, and medical imaging. Nowadays, detectors and custom ICs are routine in high-energy physics applications. Electronic readout circuits have become a key part of every modern detector system. Many sensing circuits in detectors depend upon accumulating charge on a capacitor. The charge uncertainty on the capacitor when it is reset causes a signal error known as reset noise. Therefore, low noise readout circuitry capable of driving high input capacitance is essential for detector systems.

The concept of concurrent multiband low-noise-amplifiers (LNAs) is introduced. A systematic way to design concurrent multiband integrated LNAs in general is developed. Applications of concurrent multiband LNAs in concurrent multiband receivers together with receiver architecture are discussed. Experimental results of a dual-band LNA implemented in a 0.35m CMOS technology as a demonstration of the concept and theory is presented.

Sixty-gigahertz power (PA) and low-noise (LNA) amplifiers have been implemented, based on algorithmic design methodologies for mm-wave CMOS amplifiers, in a 90-nm RF-CMOS process with thick 9-metal-layer Cu backend and transistor T MAX of 120 GHz/200 GHz. The PA, fabricated for the first time in CMOS at 60 GHz, operates from a 1.5-V supply with 5.2 dB power gain, a 3-dB bandwidth 13 GHz, a P 1dB of +6.4 dBm with 7% PAE and a saturated output power of +9.3 dBm at 60 GHz. The LNA represents the first 90-nm CMOS implementation at 60 GHz and demonstrates improvements in noise, gain and power dissipation compared to earlier 60-GHz LNAs in 160-GHz SiGe HBT and 0.13-m CMOS technologies. It features 14.6 dB gain, an IIP 3 of 6.8 dBm, and a noise figure lower than 5.5 dB, while drawing 16 mA from a 1.5-V supply. The use of spiral inductors for on-chip matching results in highly compact layouts, with the total PA and LNA die areas with pads measuring 0 35 0 43 mm 2 and 0 35 0 40 mm 2 , respectively. Index Terms-Characteristic current densities, CMOS millimeter-wave integrated circuits, MAX , T , inductors, low-noise amplifier (LNA), millimeter-wave, noise figure, power amplifier (PA), receiver, transformers, V-band, 60 GHz.

This paper presents an analysis of sub-2.5-V topologies and design methodologies for SiGe BiCMOS and sub-90nm CMOS building blocks to be used in the next generation of 40-100 Gb/s wireline transceivers. Examples of optimal designs for 40-80Gb/s broadband low-noise input comparators, low-voltage high-speed MOS- and BiCMOS CML logic gates, 30-100 GHz low-noise oscillators, and 40/80 GHz output drivers with wave shape control are provided.

Significant progress has been made in systems that interpret the electrical signals of the brain in order to control an actuator. One version of these systems senses neuronal extracellular action potentials with an array of up to 100 miniature probes inserted into the cortex. The impedance of each probe is high, so environmental electrical noise is readily coupled to the neuronal signal. To minimize this noise, an amplifier is placed close to each probe. Thus, the need has arisen for many amplifiers to be placed near the cortex. Commercially available integrated circuits do not satisfy the area, power and noise requirements of this application, so researchers have designed custom integrated-circuit amplifiers. This paper presents a comprehensive survey of the neural amplifiers described in publications prior to 2008. Methods to achieve high input impedance, low noise and a large time-constant high-pass filter are reviewed. A tutorial on the biological, electrochemical, mechanical and electromagnetic phenomena that influence amplifier design is provided. Areas for additional research, including sub-nanoampere electrolysis and chronic cortical heating, are discussed. Unresolved design concerns, including teraohm circuitry, electrical overstress and component failure, are identified.

The design of a miniaturized FM radio transmitter using a tunnel diode as the main active element to broadcast information regarding body activity such as muscle and heart potentials to a remote receiver and recorder is reported. This FM transmitter has extremely high sensitivity. A maximum value of 500 kc/mV is obtained. The equivalent input noise of the complete transmitter

This paper describes a high-performance strain sensing microsystem. A MEMS capacitive strain sensor converts an input strain to a capacitance change with a sensitivity of 26.5 aF per 0.1 µε. Low-noise integrated sensing electronics employing a continuous time synchronous detection architecture convert the capacitive signal to an output voltage for further signal processing. The prototype microsystem achieves a minimum detectable strain of 0.09 µε over a 10 kHz bandwidth with a dynamic range of 81 dB. The sensing electronics consume 1.5 mA from a 3V supply.

This paper reviews recent research conducted at the University of Toronto on the development of CMOS transceivers aimed at operation in the 90-170-GHz range. Unique nanoscale CMOS issues related to millimeter-wave circuit design in the 65-nm node and beyond are addressed with an emphasis on transistor and top-level layout issues, low-voltage circuit topologies, and design flow. A Doppler transceiver and two receivers fabricated in a 65-nm GPLP CMOS technology are described, along with a single pole, double throw antenna switch with better than 5-dB insertion loss and 25-dB isolation in the entire 110-170-GHz band. The first receiver has an IQ architecture with a fundamental frequency voltage-controlled oscillator, and is intended for wideband passive imaging applications at 100 GHz. The measured noise figure and downconversion gain are 7-8 and 10.5 dB, respectively, while the 3-dB bandwidth extends from 85 to 100 GHz. The second receiver has double-sideband architecture, operates in the 135-145-GHz range (the highest for CMOS receivers), and features an 8-dB gain LNA, a double-balanced Gilbert cell mixer, and a dipole antenna. The 90-94-GHz Doppler transceiver, the highest frequency reported to date in CMOS, is intended for the remote monitoring of respiratory functions. A Doppler shift of 30 Hz, produced by a slow-moving (4.8 cm/s) target located at a distance of 1 m, was measured with a transmitter output power of approximately +2 dBm and a phase noise of 90 dBc/Hz at 1 MHz offset. The range correlation effect is demonstrated for the first time in CMOS by measuring the phase noise of the received baseband signal at 10-Hz offset, clearly indicating that 1 noise has been canceled and it does not pose a problem in short-range applications, where neither a phase-locked loop nor a frequency divider are needed.

A novel low-cost QFN (Quad Flat Non-Leaded) package is introduced for GaAs MMIC packaging. The air-cavity QFN package is designed and implemented with an HTCC process using Alumina substrate. To operate the package up to 40 GHz, several key methods are proposed in this paper. A low noise and a buffer amplifier are packaged for practical application examples and compared with bare die measurements to verify the QFN package performance. A maximum of 4.5 dB insertion loss degradation occurred at 40 GHz. To authors' knowledge, this is the highest operating frequency for QFN type packages with low loss ever reported.

Significant progress has been made in systems that interpret the electrical signals of the brain in order to control an actuator. One version of these systems senses neuronal extracellular action potentials with an array of up to 100 miniature probes inserted into the cortex. The impedance of each probe is high, so environmental electrical noise is readily coupled to the neuronal signal. To minimize this noise, an amplifier is placed close to each probe. Thus, the need has arisen for many amplifiers to be placed near the cortex. Commercially available integrated circuits do not satisfy the area, power and noise requirements of this application, so researchers have designed custom integrated-circuit amplifiers. This paper presents a comprehensive survey of the neural amplifiers described in publications prior to 2008. Methods to achieve high input impedance, low noise and a large time-constant high-pass filter are reviewed. A tutorial on the biological, electrochemical, mechanical and electromagnetic phenomena that influence amplifier design is provided. Areas for additional research, including sub-nanoampere electrolysis and chronic cortical heating, are discussed. Unresolved design concerns, including teraohm circuitry, electrical overstress and component failure, are identified.

A CMOS preamplifier optimized for piezoelectric transducers is presented. The extensive use of CMOS-compatible lateral bipolar transistors (CLBT's) and careful layout leads to a very low noise along with good untrimmed dc and ac characteristics. These features make it competitive with bipolar and JFET realizations. In addition, long coaxial lines can be driven without significant alteration of performance using the two uncommitted on-chip buffers. This circuit was fabricated in a standard 3 -p i p-well CMOS technology, opening perspectives to monolithic integration of data acquisition subsystems.

Columnar CsI(Tl) screens are now routinely used in indirect digital x-ray imaging detectors. The CsI(Tl) scintillator provides high density, high atomic number, and high scintillation efficiency. These properties, coupled with the fact that CsI(Tl) can be grown in columnar form, provide excellent spatial resolution, high x-ray absorption, and low noise resulting in detectors with high overall detective quantum efficiency (DQE(f)). While such screens are now commercially available, developments leading to further improvements in scintillator performance are ongoing at RMD. Here we report on the recent progress in developing very thin (10 µm) to very thick (~3 mm) columnar screens and discuss their application potential in digital radiology and nuclear medicine.

This letter presents a novel Hartley low phase noise differential CMOS voltage-controlled oscillator (VCO). The low noise CMOS VCO has been implemented with the TSMC 0.18m 1P6M CMOS technology and adopts full PMOS to achieve a better phase noise performance. The VCO operates from 4.02 to 4.5 GHz with 11.3% tuning range. The measured phase noise at 1-MHz offset is about 119 dBc/Hz at 4.02 GHz and 122 dBc/Hz at 4.5 GHz. The power consumption of the VCO core is 6.75 mW.