Subtraction Circuit Research Articles

Brain Feature Extraction With an Artifact-Tolerant Multiplexed Time-Encoding Neural Frontend for True Real-Time Closed-Loop Neuromodulation.

Closed-loop neuromodulation is emerging as a more effective and targeted solution for the treatment of neurological symptoms compared to traditional open-loop stimulation. The majority of the present designs lack the ability to continuously record brain activity during electrical stimulation; hence they cannot fully monitor the treatment's effectiveness. This is due to the large stimulation artifacts that can saturate the sensitive readout circuits. To overcome this challenge, this work presents a rapid-artifact-recovery time-multiplexed neural readout frontend in combination with backend linear interpolation to reconstruct the artifact-corrupted local field potentials' (LFP) features. Our hybrid technique is an alternative approach to avoid power-hungry large-dynamic-range readout architectures or large and complex artifact template subtraction circuits. We discuss the design and measurements of a prototype implementation of the proposed readout frontend in 180-nm CMOS. It combines time multiplexing and time-domain conversion in a novel 13-bit incremental ADC, requiring only 0.0018 mm2/channel of readout area despite the large 180-nm CMOS process used, while consuming only 4.51 μW/channel. This is the smallest reported area for stimulation-voltage-compatible technologies (i.e. ≥ 65 nm). The frontend also yields a best-in-class peak total harmonic distortion of -72.6 dB @2.5-mVpp input, thanks to its implicit DAC mismatch-error shaping property. We employ the chip to measure brain LFP signals corrupted with artifacts, then perform linear interpolation and feature extraction on the measured signals and evaluate the reconstruction quality, using a set of sixteen commonly used features and three stimulation scenarios. The results show relative accuracies above 95% with respect to the situation without artifacts. This work is an ideal candidate for integration in high-channel-count true closed-loop neuromodulation systems.

Design and research of wireless optical power meter based on IoT big data and physical quantity

In response to the problems of low accuracy, high radiation, and high power consumption in industrial UV power detection, the author proposes a design scheme based on a low-power microcontroller MSP430 as the core controller, two UV photoelectric sensors as detectors, and wireless LoRa as the data transmission method. This scheme adopts dual sensors and achieves photoelectric conversion and ambient light filtering through a subtractive amplification circuit. It also uses high-precision programmable AD acquisition chips to achieve controllable amplification of the signal and convert analog signals into digital quantities for transmission to the main controller MSP430. The improved sliding average filtering method is used to perform digital filtering on the collected data and calculate the corresponding power value, data is transmitted to the upper computer for real-time display through wireless Lora. Research and experiments have shown that the dual sensors have a good agreement with the standard values. The difference between the measured values after digital filtering and the standard values is small, and the linearity of digital filtering is good. It can be seen from the two figures that the higher the power value, the higher the lighting temperature. It has been proven that the entire system operates stably, with high accuracy, low power consumption, and can remotely and real-time detect changes in ultraviolet light power. It can be widely used in the field of industrial ultraviolet light detection.

A power-efficient dynamic-time current mode comparator

This paper presents a power-efficient dynamic-time current comparator for current mode signal processing. The proposed circuit utilizes a switched feedback-based inverter and a clock-shaping circuit. The switched feedback-based inverter can detect the polarity of the sensed current from the current subtraction circuit. While the clock-shaping circuit can manage the power consumption. Since the proposed current comparator exhibits a high sensitivity to ultra-low input current with a low input offset, it can be exploited in a current mode successive-approximation-register analog-to-digital converters for a wide range of wearable applications. Moreover, a design methodology for an efficient and robust current comparator is presented. The circuit is designed and simulated in TSMC 0.13 µm CMOS technology, and occupies a silicon area of 7834 µm2. The proposed current comparator consumes a power of 14 µW with a single power supply of 1.2 V. It provides a resolution of 2 nA, and a delay of 4.6 ns. Moreover, the post-layout simulation results indicate a good agreement compared to the prior art.

A New Piecewise-Compensated Bandgap Reference Circuit with a Trimming Procedure

A new CMOS bandgap reference (BGR) circuit with a piecewise-compensation circuit and a trimming network is proposed and designed to obtain a bandgap reference voltage with a low-temperature coefficient and a high precision, taking into account the effect of non-ideal factors on the results. The proposed piecewise compensation circuit is designed to achieve a constant reference voltage by using a current mirror to mirror the current, combined with a subtractive circuit and an additive circuit to obtain a low-temperature coefficient over an extensive temperature range. The trim network part is used to change the voltage value of the output reference by controlling the magnitude of the resistance value of the resistors connected to the circuit. The design and simulation of the proposed bandgap reference circuit are obtained by using Cadence Spectre simulation by SMIC 0.18 μm CMOS technology. The results indicates that when the power is 3.3 V and the temperature scope is within -40 °C to 125 °C, the output voltage is 1.2 V with the temperature coefficient equal to 0.658 ppm/°C. When the power varies within 3.2 V to 3.4 V, the linear regulating rate is 0.001019 %/V.

An Effective Method for Improving Low-Frequency Response of Geophone

The natural frequency of traditional velocity sensors such as moving coil geophones limits their measurable low-frequency range, and the damping ratio affects the flatness of the sensor in the amplitude and frequency curves, resulting in variations in sensitivity over the available frequency range. In this paper, the structure and working principle of the geophone are analyzed and its dynamics are modeled. After synthesizing the negative resistance method and zero-pole compensation, two commonly adopted low-frequency extension methods, a method for improving low-frequency response, which is a series filter and a subtraction circuit to increase the damping ratio, is proposed. Applying this method to improve the low-frequency response of the JF-20DX geophone, which has a natural frequency of 10 Hz, results in a flat response to acceleration in the frequency range from 1 to 100 Hz. Both the PSpice simulation and actual measurement show a much lower noise level via the new method. Testing the vibration at 10 Hz, the new method has a 17.52 dB higher signal-to-noise ratio than the traditional zero-pole method. Both theoretical analysis and actual measurement results show that this method has a simple circuit structure, introduces less circuit noise, and has a low-frequency response improvement effect, which provides an approach for the low-frequency extension of moving coil geophones.

Controllable modulation of the oxygen vacancy-induced adjustment of memristive behavior for direct differential operation with transistor-free memristor.

To achieve the goal of neuromorphic computing hardware implementation with extremely high efficiency, low power consumption, and high density, it is necessary to develop transistor-free memristors and implement differential operation without subtraction circuits. In this study, argon ion irradiation was used during the fabrication process of a single crystalline LiNbO3 (LN) thin film to controllably introduce oxygen vacancies (OVs) into the bottom surface, which realized the modulation of OVs based on the excellent environment provided by a single-crystalline thin film. The memristive behavior of memristors was then modulated by regulating the distribution of OVs, and the effect of OVs distributed near the bottom surface of the single crystalline LN thin film on the memristive behavior was analyzed. In this way, two transistor-free memristors with opposite memristive behavior directions were fabricated. Two transistor-free memristors exhibit excellent synaptic plasticity and reliable multilevel resistance states. Based on two transistor-free memristors, a novel differential pair was constructed. Hardware implementations of direct differential operation without subtraction circuits were achieved. This study provides a new pathway to develop a transistor-free memristor and achieve differential operation without subtraction circuits in neuromorphic computing, which will simplify the peripheral circuits, improve integration density, and reduce power consumption and latency.

A Triode-Based Analog Gate and Its Application in Chaotic Circuits

Signum and absolute value functions show great potential in chaos generation. Aiming to design an easy-to-use non-smooth circuit component, a Triode-based Analog Gate (TAG) is designed, which consists of only one triode, two op-amps and four resistors for analog signal selection. By choosing external resistors and signals, TAG can be easily extended to absolute value circuit, scalar multiplication circuit, analog selector-mixed subtraction circuit, sum signal selector circuit and piecewise selector circuit. The importance of this class of circuit modules is intensified by its low cost, high accuracy, easy integration and expansion. In this report, a hyperchaotic circuit, a circuit for attractor doubling and multi-scroll generation are consequently designed based on TAG circuits showing their great flexibility and extendibility.

Measurement system of ultra‐low moisture content in oil based on the microwave transmission method

AbstractAs an important index of industrial oil, moisture content affects the performance of oil. With the increase of requirement to the oil quality, the measurement of ultra‐low moisture content is gradually concerned. To achieve nondestructive measurement of the moisture content in oil, this paper analyzes the principle of dielectric loss of oil‐water mixture and proposes a measurement system based on the microwave transmission method. The hardware of the system, horn antenna, and experimental device were designed and built. The system uses a subtracter circuit together with a high‐performance microwave chip and high‐precision analog‐to‐digital converter to detect 1dB microwave attenuation. The results showed that the system can measure the moisture content of 0.01%–0.8% in quenching oil and the single detection absolute error is less than ±0.05%, and the average detection absolute error of 10 detections is less than ±0.02%. This study is useful for nondestructive detection of the moisture content in oil and provides a reference for related product development.

Efficient Designs of Quantum Adder/Subtractor Using Universal Reversible Gate on IBM Q

Reversible arithmetic and logic unit (ALU) is a necessary part of quantum computing. In this work, we present improved designs of reversible half and full addition and subtraction circuits. The proposed designs are based on a universal one type gate (G gate library). The G gate library can generate all possible permutations of the symmetric group. The presented designs are multi-function circuits that are capable of performing additional logical operations. We achieve a reduction in the quantum cost, gate count, number of constant inputs, and delay with zero garbage, compared to relevant results obtained by others. The experimental results using IBM Quantum Experience (IBM Q) illustrate the success probability of the proposed designs.

Prototype of simultaneous bidirectional data-transmitter in 65 nm CMOS

This article presents a design and implementation of an I/O circuit block capable of simultaneous bidirectional data-transmission in CMOS integrated circuits. Merging data-transmitter and receiver into common bonding pad is feasible not only to reduce the number of transmission lines from a considerable number of chips, but also to realize more area-efficient data handling in consequence of flexible inter-chip communication. This feature is attractive from the viewpoint of detector systems in high energy experiments, in which reducing materials such as cables from silicon trackers in inner vertex layers is of major importance to suppress multiple-scattering and to achieve good overall detector performances. The circuit block presented here is designed on the basis of a current subtraction circuit and two distinct current-mode logic drivers. Its principle is also applicable to widely-used low-voltage differential signal drivers and easy for process migration. The prototype chip was fabricated in a 65 nm CMOS technology. Working principle has been demonstrated in preliminary laboratory testing.

Характеристики обнаружения когерентной системы селекции движущихся целей при рассогласовании параметров квадратурных каналов.

ntroduction. Operation of adaptive system of moving targets selection is considered, which is represented by single intermittent subtractor with coherent accumulator, which is tuned in frequency. System of moving targets selection is made in the form of two quadrature channels, in which high-frequency passive interference and signal from moving object are converted to video frequency with subsequent rejection, accumulation and comparison with threshold level. Setting the task. Investigation of the effect of the inevitable in practice amplitude and phase misalignments of quadrature channel parameters on the detection characteristics of the adaptive selection system of moving targets. Method. Method of complex variable is used, in which passive interference and signal from moving object at input and output of adaptive selection system of moving targets are presented in the form of pair of real components shifted in phase by ninety degrees. Results. Models of passive interference and signal from moving object are presented taking into account possible in practice amplitude and phase mismatches of quadrature channels parameters. The structure of the processing device is shown, which includes a series-connected generator of quadrature components of passive interference and a signal from a moving object, an adaptive cutting filter in the form of a single intermittent subtraction circuit with a frequency-tuned rejection zone, an adaptive coherent accumulator and a threshold device. Expressions are obtained for complex correlation functions of passive interference and signal from moving object at output of coherent accumulator taking into account inevitable amplitude and phase mismatches of quadrature channels parameters. Dependencies of probability of correct detection of signal from moving object against the background of passive interference from value of deviation of transmission coefficients of quadrature channels and phase mismatch of reference voltages for different values of average frequency of spectral density of passive interference are calculated and constructed. Conclusion. Significant dependence of probability of correct detection of signal from moving object on average frequency of spectral density of passive interference, as well as amplitude and phase mismatches of quadrature channels parameters is shown.

A high-order curvature compensated voltage reference based on lateral BJT

This paper presents a curvature compensated voltage reference (VR), which is based on lateral PNP bipolar junction transistor (BJT). The proposed VR is fabricated in 0.18 μm CMOS process. The circuit consists of two first-order current-mode band gap references (BGR) and a subtraction circuit. Temperature characteristics of lateral PNP BJT is utilized for temperature curvature compensation. Moreover, in order to reduce the errors introduced by the conventional subtraction circuit, an improved subtraction circuit is proposed for improving performance of curvature compensation. Test results of prototype chips show the proposed VR has an average 2.36 ppm/° C within temperature range of −40 ° C to 120 °C. Power supply rejection ratio (PSRR) of the proposed VR achieves 69.5 dB at 100 Hz.

Dual anode single-photon avalanche diode for high-speed and low-noise Geiger-mode operation.

The after-pulsing effect is a common problem in high-speed and low-noise single-photon detection based on single-photon avalanche diodes (SPADs). This article presents a dual anode InGaAs/InP SPAD (DA-SPAD) with two separate anode output ports that can be utilized for discriminating relatively weak avalanche signals, providing a simple and robust configuration of the SPAD-based single-photon detection system. Weak avalanche signals with amplitudes below the amplitude of the parasitic capacitive response of the SPAD were easily detected by the DA-SPAD and a simple subtraction circuit. The gated Geiger-mode performance of the DA-SPAD was also investigated. At a gating frequency of 1 GHz, the detection efficiency was 20.4% with an after-pulse probability of 3.5% at a temperature of -20 °C.

Selective electroless metallization of non-conductive substrates enabled by a Fe3O4/Ag catalyst and a gradient magnetic field

The formation of printed circuit patterns on non-conductive substrates has many applications in high value sectors such as electronics manufacturing. Current semi-additive and subtractive circuit manufacturing processes use photolithography to pattern substrates coated with a thin or relatively thick metal film. This process is often wasteful and expensive. Using an innovative approach; composite Fe3O4-Ag nanoparticles were synthesized and attracted to a magnetic field. The nanoparticles catalysed electroless copper deposition. Such a catalyst is new to electroless plating and was deposited selectively on a dielectric substrate using a gradient magnetic field. In this way, subsequent electroless copper plating occurred exclusively where the magnetic field was applied, whilst the remaining surface was free of deposited metal. The advantage of this additive method of manufacture is that less material is needed and less waste is produced.

A Sub-1 ppm/°C Precision Bandgap Reference With Adjusted-Temperature-Curvature Compensation

This paper presents a precision bandgap reference with an innovative adjusted-temperature-curvature compensation circuit that obtains a good temperature coefficient (TC) over a wide temperature range. The proposed compensation circuit for enhancing the voltage accuracy of the bandgap reference combines an addition circuit, subtraction circuit, and current mirror to achieve an adjusted piecewise linear temperature current over an entire temperature range. The proposed bandgap reference was designed and fabricated using a standard Taiwan Semiconductor Manufacturing Company (TSMC) $0.18~\mu \text{m}$ 1P6M CMOS technology. Measurements on eight samples indicated that the proposed bandgap reference achieved a TC that varies from 1.67 to 10.55 ppm/° from −40 °C to 140 °C with a supply voltage of 1.8 V. The measured 547 mV reference voltage achieved a precision line regulation that is less than 0.08%/V for supply voltages between 1.3 and 1.8 V. The proposed circuit dissipated $28~\mu \text{A}$ with a supply voltage of 1.8 V, and an active area of 0.0094 mm2. The circuit was designed to operate on a low supply voltage down to 1.3 V.

전이중 통신을 위한 자기간섭 제거 기법 구현

ABSTRACT Full-duplex communication can enhance wireless capacity by enabling simultaneous transmission and reception of the signals on the same frequency spectrum. Such a benefit, however, is only achieved when strong self-interference is well canceled below a sufficient level. To achieve this goal, there have been several approaches for cancellation, each of which is combined with digital-domain cancellation for a higher gain. In this paper, we implement two self-interference cancellation techniques and integrate them with a software defined radio-based wireless communication testbed. Two cancellation techniques (antenna cancellation and noise subtraction) are implemented and the cancellation gain is measured via real experiments. The results show that the gain of the antenna placement technique highly depends on the placement of a receiving antenna and the highest gain is achieved at the expected point, and we show that combining the noise subtraction circuit with the antenna placement further improves the cancellation gain.

Wide range temperature sensor with adaptive nonlinearity cancellation (ANC) technique for HVICs

A new temperature sensor utilising an adaptive nonlinearity cancellation circuit is proposed among two base-emitter voltages (VBEPT and VBEIO) of the diode-connected bipolar junction transistors driven in saturation region with a proportional to absolute temperature current and an independent of absolute temperature current, respectively. In this way, the nonlinear effect originated from the temperature dependence of saturation current (IS) drift can be cancelled adaptively through subtraction circuits. The measurements indicate that the proposed temperature sensor can achieve a sensitivity of −9.75 mV/°C with linearity up to 99.95% over the temperature range of 170°C (−40–130°C).

Research and Design of Laser Displacement Measurement Based on the PSD

This paper introduces a kind of measuring system based on two-dimensional position sensitive detector PSD and single-chip signal processing, and have discussed the key technology. Two-dimensional position sensitive detector (2 D-PSD) is a kind of testing device of light spot position information and the output signal is a kind of current signal related to the location information. PSD output signal processing circuits are usually made by the I/V conversion circuit ,the addition, the subtraction and division arithmetic circuit. System can quickly, accurately and easily realize the position measurement, with a simple implementation, low power consumption, fast response, etc, It can be applied to many remote laser center positioning measurement and general industrial control occasions.

CupraEtch DE - Recyclable Anisotropic Etch: Differential Etch for SAP Manufacturing

The demand for ever finer circuitry especially for IC-substrate manufacturing has lead the way from the traditional subtractive circuit formation to additive, semi-additive, and modified semi-additive technology. Fully additive processing remains a niche technology, while semi-additive (SAP) and especially modified semi-additive processing (mSAP) are already widely used in the IC-substrate manufacturing business. Both SAP and mSAP require a copper seed layer in order to be able to pattern plate the desired circuitry. In SAP this seed layer consists only of a layer of electroless copper, with a thickness ranging from 0,3 μm to 1,5 μm depending on the design and manufacturer. Therefore after pattern plating and resist stripping only the thin electroless copper seed layer needs to be removed for circuit formation. Considering mSAP several different variations exist. In some cases the seed layer consists only of sputtered copper, in others it is a layer of electroless copper with strike copper plating as protective layer, and in other cases half-etched copper panels are being used. Depending on which type of mSAP was applied the seed layer thickness can be in the nanometer range but also up to 10 μm. Nevertheless for both SAP and mSAP the copper seed layer has to be removed through etching to finalize the circuit formation. Typical etching solutions contain sulfuric acid and hydrogen peroxide in addition to organic stabilizers and banking agents. Two draw-backs have been observed with peroxide based etchants; firstly the solution requires feed and bleed operation to maintain the maximal copper content and to replenish spent oxidizer, and secondly peroxide based etchants etch three-dimensionally with the same etching speed no mater if sprayed or in immersion. The first draw back has economical as well as ecological effects, since considerable amounts of chemical waste is being generated and thereby requires waste treatment. The second drawback has functional effects, since the three-dimensional etching causes undercut of the conductor tracks of several micrometers, thereby affecting the mechanical stability of the track as well as the electrical properties (i.e. impedance control). In order to prevent these two draw-backs of the typical peroxide based etchants a different etchant system has been developed. The novel etchant is based on ferric sulfate and thereby offers the possibility to regenerate the solution in bypass equipment, therefore eliminating the need for feed and bleed operation. Furthermore, besides regenerating the oxidizer pure copper is plated, which could either be re-used internally or sold to recyclers. In addition this ferric sulfate based etchant causes minute to none undercut eliminating the second draw back of peroxide based etchants. This paper describes the newly developed ferric sulfate based etchant. The focus will be on the etch performance in comparison to hydrogen peroxide etchants. In addition regeneration equipment suitable for this application will be illustrated and discussed, especially under economical and ecological aspects.

Measurement Method of Vehicle Shaft Revolution Speed Based on Capacitive Grating Sensor

Due to the narrow interior space of vehicle, the compact structure limited the method of revolution speed measurement based on photoelectric and magnetoelectric, so a new measurement method based on capacitive grating sensor is presented here. The sensor will output alternating capacitance signal by fixed the mobilizable grating on the shaft and fixed the stator grating on the bracket. The capacitance signal will turn into the corresponding sine wave signal to the speed through differential pulse width modulation circuit, subtraction circuit and low-pass filter circuit, and will output a square wave of the same frequency with the sine wave through phase locked loop circuit. Then the speed measurement will be realized by counting the signal pulse. Experiments show that this method has the characteristics of non-contact measuring and high sensitivity.