Total Input Noise Research Articles

Design and Implementation of a Test Fixture for ELF Schumann Resonance Magnetic Antenna Receiver and Magnetic Permeability Measurements

This paper presents a prototype test fixture for the absolute calibration and estimation of the equivalent magnetic flux noise of the extremely low frequency (ELF) Schumann resonant (SR) magnetic antenna receiver and rods’ magnetic permeability measurement. The test fixture, for ELF the SR detector’s calibration, consists of a constructed coil, the signal generator, and the oscilloscope. The ELF SR detector used has been operating since 2016 near the Doliana village in the Ioannina prefecture, Northwestern Greece. At precisely this spot, far away from electromagnetic noise, the whole setup and experiment took place. The experiments performed with the proposed test fixture showed a sensitivity of 70 nV/pT/Hz and an apparent magnetic permeability at around 250 for the magnetic antenna. The total sensitivity of the ELF receiver was 210 mV/pT near 20 Hz, while the total input noise was around 0.04 pT.

Analysis for Effects of Hearing Aids Performance by Applicability of Hydrophobic Nano-Coating Technique: A Pilot Study

Received November 4, 2015 Revised December 17, 2015 Accepted December 21, 2015 Address for correspondence Gi Jung Im, MD, PhD Department of OtolaryngologyHead and Neck Surgery, Korea University College of Medicine, 73 Inchon-ro, Seongbuk-gu, Seoul 02841, Korea Tel +82-2-920-5345 Fax +82-2-925-5233 E-mail logopas@korea.ac.kr Background and ObjectivesZZAlthough popular as a method for aural rehabilitation with hearing impairment, hearing aids are susceptible to inflow of foreign materials such as water, sweat, and dust, causing corrosion of the circuit board and eventual device failure. Performance of hearing aids is evaluated by assessing the applicability of hydrophobic nano-coating technique using waterproof hearing aids electronic devices. Subjects and MethodZZPerformance was evaluated using a Fonix 7000 for the maximum output sound pressure level (Max OSPL 90), high frequency average full on gain (HFA FOG), total harmonic distortion and input noise level for 13 hearing aids. Nine of the 13 hearing aids were tested after nano-coating was applied to 2.5 μm of thickness. Fro the immersion test, hearing aids were subjected to 1 m of depth of water and performance was immediately measured; they were also measured after a day and also after a month. ResultsZZIn the coated group, Max OSPL 90, HFA FOG were significantly reduced but the corrosion of the circuit board was not observed. The four hearing aids without nano-coating failed to work immediately after the immersion test. However, there were no changes in performance after a month of immersion in any of the aids. For the non-coated group, corrosion of the circuit board was observed after 1 month. ConclusionZZNano-coating is a competitive technology and an advangtage to have to ensure waterproof effect and corrosion prevention. Thus it should be recognized as essential technology to enhance performance of hearing aids. Korean J Otorhinolaryngol-Head Neck Surg 2016;59(4):281-6

A Battery-Powered Activity-Dependent Intracortical Microstimulation IC for Brain-Machine-Brain Interface

This paper describes an activity-dependent intracortical microstimulation (ICMS) system-on-chip (SoC) that converts extracellular neural spikes recorded from one brain region to electrical stimuli delivered to another brain region in real time in vivo. The 10.9-mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> SoC incorporates two identical 4-channel modules, each comprising an analog recording front-end with total input noise voltage of 3.12 μV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rms</sub> and noise efficiency factor (NEF) of 2.68, 5.9-μW 10-bit successive approximation register analog-to-digital converters (SAR ADCs), 12.4-μW digital spike discrimination processor, and a programmable constant-current microstimulating back-end that delivers up to 94.5 μA with 6-bit resolution to stimulate the cortical tissue when triggered by neural activity. For autonomous operation, the SoC also integrates biasing and clock generation circuitry, frequency-shift-keyed (FSK) transmitter at 433 MHz, and dc-dc converter that generates a power supply of 5.05 V for the microstimulating back-end from a single 1.5-V battery. Measured results from electrical performance characterization and biological experiments with anesthetized rats are presented from a prototype chip fabricated in AMS 0.35 μm two-poly four-metal (2P/4M) CMOS. A noise analysis for the selected low-noise amplifier (LNA) topology is presented that obtains a minimum NEF of 2.33 for a practical design given the technology parameters and power supply voltage. Future considerations in the SoC design with respect to silicon area and power consumption when increasing the number of channels are also discussed.

Input noise modelling of deep submicron MOSFETs

This paper presents a noise model using the channel length modulation (CLM) effect to calculate the total equivalent noise current, referred to the gate (input) of the MOSFET. It is shown here that for short channel MOSFETs the total input noise depends on the electron warming in the channel, the voltage fluctuations due to the gate polysilicon resistance, and the induced thermal noise at the gate. Taking velocity saturation effect and carrier heating effect in the gradual channel region, complete thermal noise modelling of short-channel MOSFETs including the induced gate noise and its correlation coefficients is presented.

Using High Frequency Operational Amplifiers for Low Noise Design

In this paper we present a comprehensive noise and stability analysis of both the current feedback and the voltage feedback op-amp when connected as transimpedance amplifiers with capacitive current sources. It is generally assumed that the current feedback op-amp is noisier than the voltage feedback op-amp; we show how external component values play an important role in determining the total equivalent input noise current spectral density and show that the voltage feedback op-amp may, in certain cases, be noisier than the current feedback op-amp. Both amplifier types are compared in terms of stability, noise and bandwidth; we find that the current feedback op-amp is particularly suited for operation as a transimpedance amplifier. Theoretical analysis is confirmed by simulations of equivalent circuits of the current feedback op-amp and the voltage feedback op-amp, and simulations of the macro models of two high performance commercially available op-amps, namely the Elantec EL2260 current feedback op-amp and the Elantec EL2244 voltage feedback op-amp.

A CMOS IC for portable EEG acquisition systems

We present a monolithic low-power, low-noise analog front-end electroencephalogram acquisition system. It draws only 500 /spl mu/A from a standard 9-V battery, making it suitable for use in portable systems. Although fabricated in a standard CMOS technology, by using current feedback techniques it achieves a common mode rejection ratio of 100 dB while the total input noise referred to input is kept below 1.5 /spl mu/V (rms).

Noise and small-signal performance of three different monolithic InP-based 10 Gbit/s photoreceiver OEICs

Three circuit concepts (high impedance, common gate, and transimpedance) for a 10 Gbit/s monolithic receiver OEIC consisting of an InGaAs/InP pin photodiode and InAlAs/InGaAs/InP HEMTs are compared in terms of noise and small-signal performance using on-wafer measurements. A total equivalent input noise current of 13.5 pA/√Hz within the bandwidth of the transimpedance circuit is the lowest value ever reported for a monolithic InP-based 10 Gbit/s receiver OEIC.

Design considerations of high-dynamic-range wide-band amplifiers in BiCMOS technology

Design techniques of high-dynamic-range wideband amplifiers in BiCMOS technology for matching either a telescope (capacitive) or a wire (resistive) antenna are presented. The advantage of the BiCMOS process over bipolar and CMOS ones in designing such high-performance amplifiers is theoretically studied. It is analytically shown that by optimal combination of bipolar and MOS devices, BiCMOS amplifiers can be designed that show superior performance over bipolar and CMOS realizations. The design principles were verified by measurements on a bipolar test amplifier implemented in a linear gate array of a BiCMOS technology. A total equivalent input noise level as low as 0.25 mu V/sub RMS/ within a 2.5-kHz IF band is achieved and a dynamic range of 135 dB was measured without the use of any automatic gain control.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Noise characterization of GaAs MESFETs for the design of optical amplifiers

The principal noise sources of GaAs MESFETs are taken into account in order to completely characterize the equivalent circuit model that has been utilized in the design of a low-noise small-signal amplifier for optical receivers. The total input noise current of the amplifier, due to correlated gate and drain MESFET noise, has been estimated for evaluating the excess channel noise factor F for different values of the photodiode capacitance. A method is demonstrated for easy identification of the matching network parameters and photodiode capacitance that mmimize the noise. Finally, the minimum noise gain, gain-frequency dependence, input and output voltage standing wave ratios, noise figure, and bandwidth of the amplifier are evaluated in the 8 to 12 GHz frequency range. A gain of 22.1 1 dB and a noise figure less than 3 dB in a bandwidth larger than 4 GHz are obtained.

Stability and noise performance of constant transimpedance amplifier with inductive source

The design of a low-noise wideband transimpedance amplifier which matches an inductive source is considered. The presence of an inductive source makes it difficult to design such an amplifier to meet both low-noise and stability requirements. A novel feedback configuration is proposed. The use of this configuration gives good noise performance and at the same time realizes a constant transimpedance. The stability and signal transfer conditions for four different cases are derived. Noise analysis and optimization performed for each case yield amplifiers with optimal noise performance. Four amplifiers have been designed to verify the analytical results. The amplifier is suitable to be implemented in bipolar junction transistor technology and can be used as the preamplifier in an upconversion radio receiver. A transimpedance of 220 k Omega and total equivalent input noise current density between 0.35 to 0.75 pA/ square root Hz have been achieved in the whole AM band. A reduction of two in noise current has been measured when a JFET (junction field-effect-transistor) is used as input instead of a bipolar transistor. >

Analysis of sensitivity degradation caused by the flicker noise of GaAs-MESFETs in fiber-optic receivers

The total input noise current and sensitivity of the fiber-optic receiver was calculated. The flicker noise source was included by adopting a pertinent flicker noise model. Power penalties caused by the flicker noise were calculated for various fiber-optic receivers using the calculated noise current. It has been found that the flicker noise affects the sensitivity over the whole range of the bit rates, and that the total input capacitance is an important parameter affecting the power penalty which is serious in the case of a high-impedance-type p-i-n FET receiver. The optimum feedback resistance for practical p-i-n FET receiver design is also suggested.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Input noise in the hysteretic rf SQUID: Theory and experiment

The spectral density of the low-frequency open-circuit intrinsic input noise of the hysteretic rf-biased SQUID is calculated. The noise level, which affects the optimized power sensitivity of the SQUID, is found to be strongly model dependent and thus also constitutes an interesting probe of device physics. The results of the calculation are significantly different from previous predictions. A direct measurement of the total input noise of a typical rf-biased SQUID system is reported. The results, which are consistent our calculation, correspond to a system noise temperature of 3.1±0.4 mK at a frequency of 1 kHz. This value is consistent with the Manley-Rowe equations and with previous experimentally determined upper limits.

‘Quantization’ of stochastic variables: Description and effects on the input noise sources in a BWR

A set of macrostochastic and discrete variables, with Markovian properties, is used to characterize the state of a BWR, whose input noise sources are of interest. The ratio between the auto-power spectral density (APSD) of the neutron noise fluctuations and the square modulus of the transfer function (SMTF) defines ‘the total input noise source’ (TINS), the components of which are the different noise sources corresponding to the relevant variables. A white contribution to TINS arises from the birth and death processes of neutrons in the reactor and corresponds to a ‘shot noise’ (SN). Non-white contributions arise from fluctuations of the neutron cross-sections caused by fuel temperature and steam content variations. These terms, called ‘flicker noises’ (FN) are characterized by cut-off frequencies related to time constants of reactivity feedback effects. The respective magnitudes of the shot and flicker noises depend not only on the frequency, the feedback reactivity coefficients or the power of the reactor, but also on the ‘quantization’ of the continuous variables introduced, such as fuel temperature and steam content. The effects of this last ‘quantization’ on the shapes of the noise sources and their sum are presented in this paper.

The LINEATOR&amp;#8212;A low-noise protective device

The unidirectional and low-noise properties of the Cuccia coupler have been combined with the high-power capabilities of all-copper cavities to yield a new stable protective device for a solid-state amplifier for a superpower radar. A prototype LINEATOR has been constructed and tested at 1,295 Mc, with the capability of withstanding at least 50 kw of peak incident power, providing greater than 100 db of isolation to the solid-state amplifier during the pulse. Recovery is automatic and essentially instantaneous, such that during the receiving period, the terminal insertion loss is approximately 0.3 db, with a total effective input noise temperature less than 35° K. The LINEATOR is a passive nonreciprocal electron-beam-type device, similar to a circulator, except with a linear, rather than a circular, configuration. The prototype model was constructed with four ports, three of which are for signal-handling purposes, and one is for initial beam noise removal.

An Operational Ruby Maser for Observations at 21 Centimeters with a 60-Foot Radio Telescope

A maser preamplifier designed for radiometry at a wavelength of 21 cm is described. The maser is mounted at the focus of the 60-ft reflector of the Harvard College Observatory and is being used principally for observations of hydrogen-line radiation from extra-galactic nebulae. An automatic gain stabilization system for the maser using a modulated-noise reference signal is described and an example of an observation made with this stabilization scheme is included. The total input noise temperature of the radiometer is 85°K, without the gain stabilization, and 148°K with the stabilization.