Voltage Noise Source Research Articles

High-Frequency Mathematical Model for Common-Mode Noise Voltage of Buck Converter

This paper proposes the high-frequency mathematical model for the common-mode noise voltage of a DC–DC buck converter. The high-frequency equivalent circuit considering the parasitic impedance is proposed, and then the impedance path of the common-mode noise is analyzed using this high-frequency equivalent circuit. The common-mode noise source generated by the switching device is divided into trapezoidal and ringing voltage noise sources and mathematically modeled. For high accuracy at high-frequency, a mathematical model of common-mode noise sources including the difference between rise and fall time is proposed using Fourier transform. The common-mode noise voltage is modeled by multiplying the impedance path and the noise source. In the results of the simulation, the mathematical model and experiment, the resonance frequency and the magnitude matched with less than 5% error. Through this, the common-mode noise is predicted accurately using the high-frequency mathematical model proposed in the paper.

Characterization of programmable integrated quantum voltage noise source with variable power spectral density

Characterization of programmable integrated quantum voltage noise source with variable power spectral density

Fabrication and Characterization of a Quantum Voltage Noise Source Chip for a Johnson Noise Thermometer

A Johnson noise thermometer (JNT) determines the thermodynamic temperature through cross-correlation measurement of the Johnson noise in a sense resistor at an unknown temperature. In the quantum voltage calibrated JNT system, a superconductive quantum voltage noise source (QVNS) is required to produce artificial pseudo-random noise to calibrate the gain of the cross-correlation electronics. In this paper, we present the design, fabrication, and characterization of the QVNS chip. Compared with our previous design, a new straightforward mirror symmetric layout is implemented. For this layout, the coplanar waveguides (CPWs) have the same lengths and transmission parameters. Equal pulse magnitudes are delivered to each Josephson junction array under the same output settings of the bipolar pattern generator. The modified QVNS chip is thereby enhanced because the quantum locking range is enlarged. A copper foil shielding package is used to eliminate crosstalk in this design. The first spectral comparison of two Josephson junction (JJ) arrays of with and without shielding is presented in this paper. The comparative results demonstrate that the shielding is effective. The abovementioned improvements enable us to synthesize both single and multitone waveforms with good spectral results, such that the chip satisfies the requirement of a QVNS-based JNT system for temperature measurements.

Noise Analysis in Pre-Amplifier Circuits Associated to Highly Sensitive Optically-Pumped Magnetometers for Geomagnetic Applications

This paper analyzes the noise sources in photoelectric detection circuits with several low-noise operational amplifiers cores. The fabricated circuits are low-noise pre-amplifiers that are used for optically pumped magnetometers. In the proposed circuits, the noise levels of equivalent output voltage are calculated, and the results are in accordance with measurements. With a cooperation of several operational amplifiers, we select LT1028 from linear technologies as the core for our detection circuit, which has an output signal-to-noise ratio of more than 2 × 105 up to the frequency of 100 kHz. By analyzing the individual noise sources in the detection circuit, the dominant noise source is confirmed as the photocurrent shot noise below 200 kHz. Beyond this frequency, the voltage noise source in the operational amplifier dominates. Besides, the lamp power, the radio frequency (RF) power, the temperature variations, and their influences on the sensitivity are studied and optimized. Finally, an optically pumped magnetometer with cesium head is established, showing an intrinsic sensitivity of 85 fT/√Hz. This sensitivity is realized under a geomagnetic magnetic field strength of 53 μT.

Analysis and Comparison of the Radiated Electromagnetic Interference Generated by Power Converters With Si MOSFETs and GaN HEMTs

In this article, the effects of the parameters of GaN HEMTs and Si mosfet s and the load conditions on the radiated electromagnetic interference (EMI) are analyzed based on the compositions of the equivalent noise voltage sources. These compositions include the rising and falling edges of the switching voltages, the zero-voltage-switching voltage drops and the parasitic ringing. The radiated EMI from two identical dual-active bridge converters with GaN HEMTs and Si mosfet s is investigated and compared. Experiments were conducted to validate the analysis.

Measurement of the Melting Point of Gallium Using a Johnson Noise Thermometer

We measured the thermodynamic temperature of the melting point of gallium $T_{\mathrm {Ga}}$ using a Johnson noise thermometer (JNT) with an integrated quantum voltage noise source (IQVNS) as a reference. $T_{\mathrm {Ga}}$ was calculated using the fundamental constants recommended by the Committee on Data for Science and Technology (CODATA) for the revision of the International System of Units (SI). The measured $T_{\mathrm {Ga}}$ is consistent with the value defined in the International Temperature Scale of 1990.

Common mode electronic noise in differential circuits

Differential circuits are assumed to reject common-mode noise yet no parameter is available to describe that rejection as the Common Mode Rejection Ratio (CMRR) applies only to deterministic signals, not to random noise. We propose a model and a method to analyze the contribution of the input common-mode electronic noise to the output voltage noise of differential circuits. The analysis shows that the same parameter-matching conditions that improve the CMRR determine common-mode noise rejection but CMRR is more sensitive to mismatching. For example, a low-frequency CMRR as low as 8 dB implies that more than 82% of common-mode noise is rejected. Thus, often only differential-mode noise is relevant. However, if the equivalent input current noise sources predominate over equivalent input voltage noise sources, cross-correlation between them partially yields common-mode noise that will also be rejected. We also propose a simple test that yields an estimate of that correlation.

Low-Frequency Noise Investigation of 1.09 μm GaAsBi Laser Diodes.

GaAsBi is a suitable and very attractive material system to be used as an active layer in laser diodes (LDs). To understand the performance and the reliability of such devices and also for further laser diode improvements, the origin of noise sources should be clarified. A detailed study of near-infrared 1.09 μm wavelength GaAsBi type-I laser diodes using the low-frequency noise spectroscopy in a temperature range of (180–300) K is presented. Different types of voltage fluctuation spectral density dependencies on the forward current far below the lasing threshold have been observed. According to this, investigated samples have been classified into two groups and two equivalent noise circuits with the corresponding voltage noise sources are presented. Calculations on the voltage spectral density of the electrical noise and current-voltage characteristic approximations have been performed and the results are consistent with the experimental data. The analysis showed that one group of LDs is characterized by 1/fα-type electrical fluctuations with one steep electrical bump in the electrical noise dependence on forward current, and the origin of these fluctuations is the surface leakage channel. The LDs of the other group have two bumps in the electrical noise dependence on current where the first bump is determined by overall LD defectiveness and the second bump by Bi-related defects in the active area of LD with characteristic Lorentzian-type fluctuations having the activation energy of (0.16–0.18) eV.

Properties of the surface generation-recombination noise in 1.94 µm GaSb-based laser diodes

A detail investigation of generation-recombination (g-r) noise in 1.94 µm GaSb-based type-I ridge waveguide laser diodes (LDs) has been performed in a temperature range (230–295) K. Lorentzian-type noise spectra have been observed in the current range below the threshold at the forward and reverse biases of the LDs with the same characteristic time (3.7 μs) and activation energy (≈0.37 eV) of charge carriers transitions associated with the g-r processes. An equivalent electrical circuit possessing the voltage noise source is presented, which allows the description of both the current-voltage characteristic and the voltage fluctuation spectral density of the laser diode. Results indicate that the origin of the g-r noise in the investigated samples is the surface recombination caused by the surface leakage current channel between n+GaSb and p+GaSb contacts, which is practically independent from the applied bias polarity.

Development of quantum voltage noise source chip for precision measurement of Boltzmann constant

The Johnson noise thermometer is used to precisely measure Boltzmann constant by comparing the thermal noise caused by charge movement and the quantized voltage reference noise synthesized by the quantum voltage noise source (QVNS). The QVNS signal is synthesized based on quantized voltage pulses produced by two channels of superconducting Josephson junction arrays, which are designed for cross-correlation electronics. The Nb/NbxSi1-x/Nb Josephson junction is used as a core device of QVNS chip in this work for its non-hysteretic current-voltage (I-V) characteristics and conveniently adjustable barrier parameters.In this paper, we present the design consideration, fabrication process, and measurement results of the QVNS chip. The QVNS chip contains two Josephson junction arrays, each consists of four 6 μm×12 μm junctions and is embedded in a 50 Ω coplanar waveguide transmission line. The random noise in signals from the two driven channels is eliminated by cross-correlation, and then an accurate quantum noise is obtained. Test chips with different areas of Josephson junctions are also designed on the same mask, aiming at estimating the variation range of Ic. The typical fabrication process for voltage standard chips in our laboratory is used for preparing the QVNS chip.The sample is measured at 4.2 K. The DC I-V curve shows that the critical current Ic is 6.1 mA. The I-V characteristics of the junctions under 5 GHz microwave radiation are measured. For a series array of four junctions, a 41.44 μV one-stage Shapiro step is observed. Calculation shows that the error between the measurement and theoretical value of 41.36 μV is about 1.9‰, which means that the QVNS chip performs well under microwave radiation and can be used for synthesizing the AC quantum voltage reference noise.A single-frequency 100 kHz sinusoidal waveform is synthesized by the QVNS chip under pulse driven signal. A spectrum of the synthesized sinusoidal waveform shows a single peak, which means that the digital pulse signal is perfectly filtered by Josephson junction arrays and the synthesized signals possess quantum accuracy. The results indicate that our chip has good dynamic response and works well in synthesizing a single-frequency AC quantum voltage signal. This work can provide core devices for the noise thermometry system and support the precise measurement of Boltzmann constant as well as redefinition of Kelvin in future. As a next step, the design and package will be further improved, and the probe module will be optimized to reduce the measurement uncertainty.

The NIST Johnson Noise Thermometry System for the Determination of the Boltzmann Constant.

In preparation for the redefinition of the International System of Units (SI), five different electronic measurements of the Boltzmann constant have been performed using different Johnson noise thermometry (JNT) systems over the past seven years. In this paper, we describe in detail the JNT system and uncertainty components associated with the most recent National Institute of Standards and Technology (NIST) determination of the Boltzmann constant: k = 1.380642 9(69) × 10-23 J/K, with a relative standard uncertainty of 5.0 × 10-6 and relative offset of -4.05 × 10-6 from the Committee on Data for Science and Technology (CODATA) 2014 recommended value. We discuss the input circuits and the approach we used to match the frequency response of two noise sources. We present new measurements of the correlated noise of the 4 K on-chip resistors in the quantum-accurate, pseudorandom, voltage-noise source, which we used to estimate the correlated, frequency-dependent, nonthermal noise in our system. Finally, we contrast our system with those used in other measurements and speculate on future improvements.

Measurement of the Boltzmann constant by Johnson noise thermometry using a superconducting integrated circuit

We report on our measurement of the Boltzmann constant by Johnson noise thermometry (JNT) using an integrated quantum voltage noise source (IQVNS) that is fully implemented with superconducting integrated circuit technology. The IQVNS generates calculable pseudo white noise voltages to calibrate the JNT system. The thermal noise of a sensing resistor placed at the temperature of the triple point of water was measured precisely by the IQVNS-based JNT. We accumulated data of more than 429 200 s in total (over 6 d) and used the Akaike information criterion to estimate the fitting frequency range for the quadratic model to calculate the Boltzmann constant. Upon detailed evaluation of the uncertainty components, the experimentally obtained Boltzmann constant was J K−1 with a relative combined uncertainty of . The value of k is relatively lower than the CODATA 2014 value (Mohr et al 2016 Rev. Mod. Phys. 88 035009).

A Boltzmann constant determination based on Johnson noise thermometry

A value for the Boltzmann constant was measured electronically using an improved version of the Johnson Noise Thermometry (JNT) system at the National Institute of Standards and Technology (NIST), USA. This system is different from prior ones, including those from the 2011 determination at NIST and both 2015 and 2017 determinations at the National Institute of Metrology (NIM), China. As in all three previous determinations, the main contribution to the combined uncertainty is the statistical uncertainty in the noise measurement, which is mitigated by accumulating and integrating many weeks of cross-correlated measured data. The second major uncertainty contribution also still results from variations in the frequency response of the ratio of the measured spectral noise of the two noise sources, the sense resistor at the triple-point of water and the superconducting quantum voltage noise source. In this paper, we briefly describe the major differences between our JNT system and previous systems, in particular the input circuit and approach we used to match the frequency responses of the two noise sources. After analyzing and integrating 50 d of accumulated data, we determined a value: J K−1 with a relative standard uncertainty of and relative offset from the CODATA 2014 recommended value.

Measuring the Boltzmann’s Constant Using Superconducting Integrated Circuit

We report on our progress in measuring the Boltzmann’s constant by Johnson noise thermometry (JNT) using an integrated quantum voltage noise source (IQVNS) that is fully implemented with superconducting integrated circuit technology. The IQVNS generates calculable pseudo white noise voltages to calibrate the JNT system. Thermal noise of a resistor placed at the temperature of the triple point of water was measured precisely by the IQVNS-based JNT. We accumulated more than 2000 data points to determine the Boltzmann’s constant. The experimentally obtained Boltzmann’s constant was $k_{\mathrm {exp}} = 1.3806493 \times 10^{-23}$ J/K with a relative statistical uncertainty of $8.6 \times 10^{-6}$ , which agreed well with the 2014 Committee on Data for Science and Technology value with a relative offset of $+ 0.6\times 10^{-6}$ .

Demonstration of Johnson noise thermometry with all-superconducting quantum voltage noise source

We present a Johnson noise thermometry (JNT) system based on an integrated quantum voltage noise source (IQVNS) that has been fully implemented using superconducting circuit technology. To enable precise measurement of Boltzmann's constant, an IQVNS chip was designed to produce intrinsically calculable pseudo-white noise to calibrate the JNT system. On-chip real-time generation of pseudo-random codes via simple circuits produced pseudo-voltage noise with a harmonic tone interval of less than 1 Hz, which was one order of magnitude finer than the harmonic tone interval of conventional quantum voltage noise sources. We estimated a value for Boltzmann's constant experimentally by performing JNT measurements at the temperature of the triple point of water using the IQVNS chip.

Johnson Noise Thermometry Based On Integrated Quantum Voltage Noise Source

We performed Johnson noise thermometry (JNT) using an integrated quantum voltage noise source (IQVNS) that generates pseudorandom noise with an RMS value determined by the product of the flux quantum, the clock frequency of IQVNS, $f_{\mathrm{clk}}$ , and a calculable coefficient. The working principle is different from the conventional QVNS. The waveform of the IQVNS was analyzed thoroughly, and the source checked to see that it worked properly as intended, particularly in regard to its applicability as a reference for JNT measurements. The thermal noise power of a resistor at the triple point of water was measured with the IQVNS to derive a value of the Boltzmann constant.

Improved design of integrated quantum voltage noise source

We present the design improvement of an integrated quantum voltage noise source (IQVNS) aimed at low-cost user-friendly Johnson noise thermometers with high accuracy. A problem in our previous design of the IQVNS was mainly associated with lax synchronization with low- and high-frequency clock signals, making the whole system complicated and less robust. We have employed on-chip generation of low-frequency clocks by downconverting a high-frequency reference clock so that the whole IQVNS operates with a single clock. Counterflow-clocking architecture has been introduced both in chip- and subsystem-level pipelines for achieving wider timing margins. The improved IQVNS has been fabricated by using our standard niobium-junction technology and successfully tested.

Design and test of component circuits of an integrated quantum voltage noise source for Johnson noise thermometry

We present design and testing of a pseudo-random number generator (PRNG) and a variable pulse number multiplier (VPNM) which are digital circuit subsystems in an integrated quantum voltage noise source for Jonson noise thermometry. Well-defined, calculable pseudo-random patterns of single flux quantum pulses are synthesized with the PRNG and multiplied digitally with the VPNM. The circuit implementation on rapid single flux quantum technology required practical circuit scales and bias currents, 279 junctions and 33mA for the PRNG, and 1677 junctions and 218mA for the VPNM. We confirmed the circuit operation with sufficiently wide margins, 80–120%, with respect to the designed bias currents.

Boltzmann Constant Measurements Using QVNS-Based Johnson Noise Thermometry at NMIJ, AIST

Among various methodologies of thermodynamic temperature measurements, Johnson noise thermometry (JNT) has an advantage that the structure and size of the temperature sensing probe are similar to conventional probes for contact thermometry. Another distinguishing feature is that the measurements are all electronic. Furthermore, the application of a quantum voltage noise source (QVNS), first introduced by the National Institute of Standards and Technology (NIST), has improved the accuracy of JNT during the past ten years. These developments have been driven under the rationale to determine the Boltzmann constant $$k$$ , in support of the proposed redefinition of the kelvin, and later to provide practical realization of the kelvin. At NMIJ, AIST, we have been developing a QVNS-based JNT system to first measure the Boltzmann constant and then aim to extend the temperature range to higher temperatures where $$T-T_{90}$$ data are lacking. An impact feature of our system is that most of our key elements have been built independently from NIST and the National Institute of Metrology, China (NIM); in particular that the Josephson junction array has been built in house at NeRI, AIST, and its driving method differs from that of either NIST or NIM. In this paper, the unique elements of the system as well as our initial results on the Boltzmann constant measurements are reported.

Integrated quantum voltage noise source for Johnson noise thermometry

We have been developing a new implementation of quantum voltage noise source (QVNS), an integrated QVNS (IQVNS), for Johnson noise thermometry (JNT) in thermal metrology. We designed an IQVNS chip based on rapid single flux quantum (RSFQ) technology. A general formula for the output power spectrum has been derived by using a Fourier analysis method, which shows that the spectrum is calculable with sufficiently small errors for practical JNT measurements.