Low-noise DC Research Articles

Cryogenic bipolar low noise dc amplifier for low frequency applications

A low-noise bipolar differential dc amplifier was studied at temperatures of 300 and 77 K. It was shown that to ensure the best amplifier performance in terms of noise figure when the operating temperature decreases from 300 to 77 K, it is advisable to use the transistor in the mode of low currents not exceeding 2 mA. It has been established that lowering the operating temperature to 77 K leads to a decrease in the input resistance of the amplifier from a value of several kiloohms to 100 Ohms, the dynamic range increases from 80 to 85 dB, and the harmonic coefficient increases from 0.09% to 1%. In addition, lowering the operating temperature to 77 K has a significant effect on the noise properties of the amplifier: the spectral density of voltage noise decreases from 1 to 0.4 nV/Hz1/2, the spectral density of current noise increases from 2.5 to 9 pA/Hz1/2, while also The threshold frequencies of 1/f noise increase: for voltage from (0.1...10) to 20 Hz and for current from (10...100) to 1000 Hz. The possibility of using an amplifier for low-temperature measurements of samples with low input resistance is substantiated.

Design and simulation of low dropout voltage regulator using 180nm technology

Low Dropout (LDO) Voltage Regulators are the linear regulators which drives upon a very small differential voltage. The main components of the Low dropout voltage regulators are Error amplifier, Pass device, voltage reference source and Voltage divider network. The low dropout voltage regulator uses a variable input to give a steady, constantly controlled, low-noise DC output voltage. This is a linear voltage regulator that includes a small voltage drop among the input as well as the output that works even when the output voltage is extremely close to the input voltage. The Error amplifier circuit which is one of the components in Low dropout voltage regulator is designed in the standard 180nm CMOS technology, with supply voltage of 1.6V, the gain of the error amplifier is 74db, Band-gap reference circuit is implemented to produce stable reference voltage which is independent of temperature variations. The bandgap reference voltage circuit gives the output voltage of 1.2V. The low dropout voltage regulator produces constant output voltage of 1.8V for the input voltage range 2.1V to 3.5V and it provides constant output voltage for load variations.

A Low-Noise DC Voltage Stabilizer Based on a General-Purpose Reference Voltage Source

A Low-Noise DC Voltage Stabilizer Based on a General-Purpose Reference Voltage Source

Dual-mode auto-calibrating resistance thermometer: A novel approach with Johnson noise thermometry.

A dual-mode auto-calibrating resistance thermometer (DART) is presented. The novel DART concept combines in one instrument the fast and accurate resistance thermometry with the primary method of Johnson noise thermometry. Unlike previous approaches, the new thermometer measures the spectral density of the thermal noise in the sensing resistor directly in a sequential measurement procedure without using correlation techniques. A sophisticated data analysis corrects the thermometer output for both the parasitic effects of the sensor wiring and the amplifier current noise. The instrument features a highly linear low-noise DC coupled amplifier with negative feedback as well as an accurate voltage reference and reference resistor to improve the gain stability over time and ambient temperature. Therefore, the system needs only infrequent calibrations with electrical quantum standards and can be operated over long intervals and a wide temperature range without recalibration. A first prototype is designed for the industrially relevant temperature range of the IEC 60751 (-200 °C to +850 °C); a later extension of the measurement range is being considered. A proof-of-principle measurement with a calibrated Pt100 sensor at room temperature yielded an uncertainty of about 100 µK/K. The final device is expected to reach uncertainties of below 10 µK/K, suitable for accurate measurements of the difference between thermodynamic temperatures and temperatures traceable to the International Temperature Scale of 1990 (ITS-90).

A 0.52 μW, 38 nV/√Hz Chopper Amplifier With a Low-Noise DC Servo Loop, an Embedded Ripple Reduction Loop, and a Squeezed Inverter Stage

To realize an ultralow-power, low-noise amplifier for bio-potential recording, we investigate three design techniques. The first technique uses a noise-efficient squeezed inverter (SQI) stage biased at the supply of the $2{V} _{\mathrm{ DSAT}}$ saturation limit. The challenge of interfacing the SQI stage with such a low supply is addressed by proposing a new capacitively-coupled chopper instrumentation amplifier (CCIA) with a low-noise DC servo loop (L-DSL) and an embedded ripple reduction loop (E-RRL). The second technique is reducing the high noise contribution of the conventional DSL. The proposed L-DSL reduces the input-referred noise (IRN) by removing the charge dividing effect. The proposed E-RRL inserted inside the gain stage cancels the offset and achieves a ripple suppression without loading the output. The CCIA is implemented using a $0.18~\mu \text{m}$ CMOS process. The measured results show that the L-DSL successfully creates a sub-Hz high-pass corner needed to block the electrode offset. The E-RRL achieves a ripple suppression of 39 dB. The CCIA achieves 32 nV/ $\surd $ Hz noise density, which is slightly increased to 38 nV/ $\surd $ Hz when the L-DSL is enabled. The integrated noise over 800 Hz bandwidth is 0.9 and 1.1 $\mu \text{V}_{\mathrm{ rms}}$ without and with the L-DSL, respectively. The mid-band gain of 39.6 dB is achieved by consuming $0.52~{\mu }\text{W}$ . These results correspond to a favorable noise efficiency factor (NEF) of 2.1 and a power efficiency factor (PEF) of 1.2.

Stability analysis and experimental validation of the supercapacitor‐assisted low‐dropout regulator

The supercapacitor-assisted low-dropout (SCALDO) regulator is a unique new design approach to develop high efficiency, high current and low noise DC–DC converters, where a supercapacitor (SC) is used in the series path of a low dropout (LDO) regulator to act as a lossless voltage dropper. In the published literature, there has been much discussion about the stability of an LDO regulator, where different approaches are applied to frequency compensate depending on the LDO architecture. Given the case that the SCALDO technique is a combination of an LDO regulator and an SC, this study presents an analysis and experimental validation of the stability, based on a 12–5 V SCALDO prototype, proving that the effect of the SC energy recovery method does not make the overall regulator carry a stability issue in general.

A Table-Top Pilot Experiment for Narrow Mass Range Light Cold Dark Matter Particle Searches

This report presents the detection framework and a proposal for a pilot table-top experiment (supported by simulations and preliminary test results) for adoption into narrow mass range light Cold Dark Matter (CDM) searches, specifically for axions or Axion-Like Particles (ALPs) in a resonant cavity-based scheme. The novelty of this proposal lies in an attempt to concentrate searches corresponding to specific axion masses of interest (coinciding with recent proposals), using multiple cavities in a symmetric scheme, instead of using noisy and complicated tuning mechanisms, and in reduction of associated hardware by employing simpler underlying instrumentation instead of heterodyne mode of detection, by means of a low-noise ac amplification and dc phase-sensitive detection scheme, in order to make a viable and compact table-top experiment possible. These simplifications could possibly be valuable in substantially reducing detection hardware, experiment complexities (and associated noise) and long run-times, while maintaining low noise similar to conventional axion searches. The feasibility of proposed scheme and the experiment design are demonstrated with some calculations, simulations and preliminary tests with artificial axion signals injected into the cavities. The technique and ideas reported here have significant potential to be developed into a small-scale table-top, narrow-range, dark matter axion/ALP spectroscopy experiment, in addition to aiding in the on-going resonant cavity-based and broadband experiments.

A Low-Noise and Quasi-Ideal DC Current Source Dedicated to Four-Probe Low-Frequency Noise Measurements

In this paper, a dc current source dedicated to fourprobe low-frequency noise measurements is presented. An output impedance value of 3 MQ with a maximum output current of 1.5 mA was achieved. The white noise level of the current source was measured to be 4 × 10 -23 A 2 · Hz-1 with a corner frequency of 30 Hz. Thanks to its quasi-ideal behavior in terms of noise level and high output impedance value, this current source can be used to measure the intrinsic noise of materials using four-point measurements without any experimental or analytical corrections.

Low Noise Programmable DC Amplifier with Remote Control

Introduction. In modern experimental technology, the direction associated with the development of information-measuring systems for recording, pre-processing and analyzing excess low-frequency noise (flicker noise) is well known. Currently, such measuring systems are mainly presented in the form of particular solutions, due to the large variety of research goals and objectives. At the same time, for automation of the experiment, multichannel measuring complexes with the possibility of flexible reconfiguration of the measuring channel according to the task are highly demanded. It is obvious that any distributed measuring channel is represented as a multi-stage scheme with given functions and parameters of each stage, which makes it difficult for the measuring system to adapt to different conditions and tasks of the experiment. The logical solution to this problem is a deep unification of all components of the measuring channel while maintaining good performance characteristics. One of the main problems with this is the evaluation of the intrinsic noise of electronic elements, which provide for changing the parameters of the amplifier.Objective. Experimental analysis of the intrinsic noise of electronic potentiometers, development of the concept and study of parameters of a low-noise DC amplifier with a high degree of unification, the possibility of external electronic control and the use of built-in characteristics correction algorithms.Materials and methods. To achieve the set result, a method for measuring the noise of electronic potentiometers was proposed and experimental studies were carried out.Results. According to the calculation results and experimental studies, it was shown that the specific noise of the electronic potentiometers corresponds to the noise of the metal-film resistors, which makes it possible to use them in low-noise amplification stages. The developed circuit solutions allow the implementation of a unified amplifying module with cascading to build low-noise measuring DC paths based on electronic potentiometers. External and internal digital control allows you to significantly improve the performance of the measuring path as a whole and allows you to adapt it to a wide range of tasks.Conclusion. As part of the study, a method was proposed for measuring the noise of electronic potentiometers, analytical and experimental studies were carried out, and a prototype of a low-noise amplifier was developed and investigated.

An All-Digital Low-Noise Switching DC–DC Buck Converter Based on a Multi-sampling Frequency Delta-Sigma Modulation with Enhanced Light-Load Efficiency

This paper presents an all-digital technique to control DC–DC switching buck converters for noise-sensitive low-power applications. The controller is designed based on a multi-sampling frequency digital delta-sigma modulator, whose sampling frequency is adjusted according to the load current. The proposed controller demonstrates the efficiency performance of the digital pulse-width modulation controller counterpart at heavy load while reducing output spikes by 37 dB without any additional processing. At light load, the controller scales down the switching frequency by scaling down delta-sigma modulator sampling frequency. Consequently, light-load efficiency is improved by more than 40% compared to its fixed frequency counterpart. In particular, the proposed solution adopts a unity-gain signal-transfer function delta-sigma modulator that avoids excess phase in the control loop. The proposed technique is compact, scalable and compatible with the standard digital CMOS implementation. Experimental and simulation results characterizing the proposed solution are provided.

A correlation noise spectrometer for flicker noise measurement in graphene samples

We present a high-resolution digital correlation spectrum analyzer for the measurement of low frequency resistance fluctuations in graphene samples. The system exploits the cross-correlation method to reject the amplifiers’ noise. The graphene sample is excited with a low-noise DC current. The output voltage is fed to two two-stage low-noise amplifiers connected in parallel; the DC signal component is filtered by a high-pass filter with a cutoff frequency of 34 mHz. The amplified signals are digitized by a two-channel synchronous ADC board; the cross-periodogram, which rejects uncorrelated amplifiers’ noise components, is computed in real time. As a practical example, we measured the noise cross-spectrum of graphene samples in the frequency range from 0.153 Hz to 10 kHz, both in two- and four-wire configurations, and for different bias currents. We report here the measurement setup, the data analysis and the error sources.

A new limit of the 129Xenon Electric Dipole Moment

We report on the first preliminary result of our 129Xe EDM measurement performed by the MIXed collaboration. The aim of this report is to demonstrate the feasibility of a new method to set limits on nuclear EDMs by investigating the EDM of the diamagnetic 129Xe atoms. In our setup, hyperpolarized 3He serves as a comagnetometer needed to suppress magnetic field fluctuations. The free induction decay of the two polarized spin species is directly measured by low noise DC SQUIDs, and the weighted phase difference extracted from these measurements is used to determine a preliminary upper limit on the 129Xe EDM.

Temperature-stabilized differential amplifier for low-noise DC measurements.

A tabletop low-noise differential amplifier with a bandwidth of 100 kHz is presented. Low voltage drifts of the order of 100 nV/day are reached by thermally stabilizing relevant amplifier components. The input leakage current is below 100 fA. Input-stage errors are reduced by extensive circuitry. Voltage noise, current noise, input capacitance, and input current are extraordinarily low. The input resistance is larger than 1 TΩ. The amplifiers were tested with and deployed for electrical transport measurements of quantum devices at cryogenic temperatures.

A full W-band low noise amplifier module for millimeter-wave applications**Project supported by the Major Program of the National Natural Science Foundation of China (No. 61434006) and the National Natural Science Foundation of China (No. 61401457).

A full W-band low noise amplifier (LNA) module is designed and fabricated. A broadband transition is introduced in this module. The proposed transition is designed, optimized based on the results from numerical simulations. The results show that 1 dB bandwidth of the transition ranges from 61 to 117 GHz. For the purpose of verification, two transitions in back-to-back connection are measured. The results show that transmission loss is only about 0.9–1.7 dB. This transition is used to interface integrated circuits to waveguide components. The characteristic of the LNA module is measured after assembly. It exhibits a broad bandwidth of 75 to 110 GHz, and has a small signal gain above 21 dB. The noise figure is lower than 5.2 dB throughout the entire W-band (below 3 dB from 89 to 95 GHz) at room temperature. The proposed LNA module exhibits potential for millimeter wave applications due to its high small signal gain, low noise, and low DC power consumption.

Active and Passive Combined Mixer for Low Flicker Noise and Low dc Offset

A direct-conversion mixer with low flicker noise and low dc offset is presented for WLAN applications. The design consists of a folded-type active mixer with a resonant inductor in cascade with a source-driven passive mixer, operating at half the conventional LO frequency. Because of this unique topology, neither direct nor indirect flicker noise of the active mixer appears at the mixer output. Moreover, the dc offset voltage from the LO self-mixing is lowered, and the burden of designing a high-frequency VCO is relieved. The measurement results show a noise figure of 12.2 dB at 10 kHz, a conversion gain of 11.4 dB, and an IIP3 of $-10.5 ~{\rm dBm}$ while the mixer consumes 8.7 mW for a 1 V supply voltage. The design is implemented in a Dongbu Hitek 0.11 $\mu{\rm m}$ CMOS process with a chip area of 1.3 $\,\times\,$ 0.98 ${\rm mm}^{2}$ .

A Low-Noise DC seismic accelerometer based on a combination of MET/MEMS sensors.

Molecular-electronic transducers (MET) have a high conversion coefficient and low power consumption, and do not require precision mechanical components thus allowing the construction of cost- and power-efficient seismic accelerometers. Whereas the instrumental resolution of a MET accelerometer within the 0.1–100 Hz frequency range surpasses that of the best Micro-Electro Mechanical Systems (MEMS) and even some force-balanced accelerometers, the fundamental inability to register gravity or, in other words, zero frequency acceleration, significantly constrains the further spread of MET-based accelerometers. Ways of obviating this inherent zero frequency insensitivity within MET technology have so far, not been found. This article explores a possible approach to the construction of a hybrid seismic accelerometer combining the superb performance of a MET sensor in the middle and high frequency range with a conventional on chip MEMS accelerometer covering the lower frequencies and gravity. Though the frequency separation of a signal is widely used in various applications, the opposite task, i.e., the combining of two signals with different bandwidths is less common. Based on theoretical research and the analysis of actual sensors' performance, the authors determined optimal parameters for building a hybrid sensor. Description and results for implementation of the hybrid sensor are given in the Experimental section of the article. Completing a MET sensor with a cost-effective MEMS permitted the construction of a low noise DC accelerometer preserving the noise performance of a MET sensing element. The work presented herein may prove useful in designing other combined sensors based on different technologies.

Low-noise single-layer YBa2Cu3O7-x dc superconducting quantum interference devices magnetometers based on step-edge junctions

We report the performance of twenty-four high temperature superconducting dc superconducting quantum interference devices (SQUIDs) whose Josephson junctions were formed from a YBa2Cu3O7-x (YBCO) grain boundary on an engineered MgO step-edge substrate. Each device has the same SQUID design with an inductance of 65 pH, and consisted of two SQUIDs with different junction widths, connected in series, and directly coupled to a large pick-up loop of 7.5 mm × 8.8 mm on a 1 × 1 cm2 chip. 58% of the devices had a peak-to-peak modulation voltage, ΔV, larger than 30 μV. The typical values of the white flux and field noise were 4.7 μΦo and 56 fT/Hz, respectively, in a magnetically shielded environment with 1/f corner frequency at 15–20 Hz. In an unshielded environment, there was no degradation of white noise.

A Phased Array Antenna Using Ferroelectric CPW Phase Shifter Active Modules

A phased array antenna using ferroelectric coplanar waveguide (CPW) phase shifter active modules is presented based on a Ba0.6Sr0.4TiO3 (BST) thin film. The ferroelectric BST thin film was deposited on an MgO substrate by using pulsed laser deposition. The active module amplifies an RF signal with low noise and changes the phase of a received RF signal to control the main beam of the array antenna. It is composed of low noise amplifier (LNA), dc block, and ferroelectric CPW phase shifter. The prototype of 6×12 phased array patch antenna with the active modules using a ferroelectric phase shifter is proposed. The proposed array antenna continuously scanned its main beam in elevation plane to 32° from its broadside direction at 11.85 GHz by applying the continuous dc voltage to the ferroelectric phase shifter.

Low noise DC to DC converters for the sLHC experiments

The development of front-end systems for the ATLAS tracker at the sLHC is now in progress and the availability of radiation tolerant buck converter ASICs enables the implementation of DC to DC converter based powering schemes. The front-end systems powered in this manner will be exposed to the radiated and conducted noise emitted by the converters. The electromagnetic compatibility between DC to DC converters and ATLAS short strip tracker hybrid prototypes has been studied with specific susceptibility tests. Different DC to DC converter prototypes have been designed following a noise optimization methodology to match the noise requirements of these front-end systems. The DC to DC converter developed in this manner presents a negligible emission of noise that was confirmed by system tests on an ATLAS tracker front-end module prototype. As a result of this, power converters can now be integrated in close vicinity of front-end chips without compromising their overall noise performance.

The National High Magnetic Field Laboratory

The National High Magnetic Field Laboratory (NHMFL) is a collaboration between Florida State University, the University of Florida, and the Los Alamos National Laboratory. The DC Field Facilities are located at the main campus for the NHMFL in Tallahassee, Florida and are described in this paper. The DC Field Facility has a variety of resistive and superconducting magnets. The DC Field Facility infrastructure, the most powerful in the world, is able to provide 57 MW of continuous low noise DC power. Constant magnetic fields of up to 45 tesla in a 32 mm bore and 20 tesla in 195 mm bore are available at no charge to the user community. The users of the facility are selected by a peer reviewed process. Roughly 400 research groups visit the lab to conduct experiments each year. Experimental capabilities provided by the NHMFL are magneto-optics, millimeter wave spectroscopy, magnetization, dilatometry, specific heat, electrical transport, ultrasound, low to medium resolution NMR, EMR, and materials processing. Measurements of properties can be made on samples at temperatures from 20 mK to 1000 K, pressures from ambient to 10 GPa, orientation and currents from 1 pA to 10 kA.