Operational Amplifier Research Articles

Adjustable resonator and anti-resonator designs for speech signal processing

Novel structures with adjustable characteristics, capable of performing the process where the vowel waveform is derived from a pulse train produced by the vibrating vocal folds and vice versa, are introduced in this work. Various design techniques are exploited to implement the required resonator and anti-resonator stages. The offered design flexibility and versatility are achieved through the employment of suitable active elements which offer electronically controlled characteristics in the resonator and anti-resonator stages, such as the Operational Transconductance Amplifiers, or through the employment of stages where their frequency behavior is digitally programmed, such as the Configurable Analog Modules included in a Field Programmable Analog Array device. The provided post-layout simulation and experimental results confirm the correct operation of the introduced structures in both the frequency and time domains.

Ho:YLF regenerative amplifier delivering 22 mJ, 2.0 ps pulses at a 1 kHz repetition rate.

We report on a high-energy, few-ps, continuous-wave pumped Ho:YLF regenerative amplifier (RA) operating in a chirped-pulse amplification arrangement. A three-stage optical parametric amplifier serves as versatile seed source emitting broadband pulses centered at 2050 nm. It provides seed pulses with 4 µJ energy within the Ho:YLF amplification bandwidth centered at 2051 nm. Thanks to the high seed pulse energy, bifurcation instabilities are mitigated and gain narrowing is reduced for such a high-gain Ho-doped RA operating at few kHz repetition rate. At 1 kHz the Ho:YLF RA emits 22.5 mJ energy pulses with a compressed pulse duration of 2.0 ps in the stable single-pulse regime. The water cooled RA features a high extraction efficiency of 31% and exhibits a remarkable stability of 0.11% rms. Doubling the repetition rate to 2 kHz, RA pulse energy reaches 15 mJ. The demonstrated 10 GW peak power at 1 kHz and the 30 W average power at 2 kHz are the highest values reported to date for few-ps RAs operating at 2 µm wavelength.

16.2-μW Super Class-AB OTA with current-reuse technique achieving 130.3-μA/μA FoM

In this paper, a single-stage Super Class-AB operational transconductance amplifier (OTA) using current reuse technique is presented. It is based on two scaled current mirrors located at the tail current nodes of input pairs, reusing the current through the cross-coupled input pairs by a current gain factor of α, and delivering new currents to the output branch, enhancing the overall transconductance (Gm) by a factor of (1+α). With adaptive biasing and local common mode feedback (LCMFB), slew rate (SR), open loop gain (AOL) and gain-bandwidth product (GBW) are improved. An prototype has been designed in TSMC 0.18-μm CMOS process. Post-simulation shows the positive and negative slew rate of 22V/μs and −38.3V/μs, respectively, a GBW of 3.72 MHz, a DC gain of 65.6 dB with a phase margin of 69.2° for a capacitive load of 70 pF. The proposed OTA consumes a total power of 16.2 μW under a 1.8V supply voltage.

Design and Analysis of a High-Gain, Low-Noise, and Low-Power Analog Front End for Electrocardiogram Acquisition in 45 nm Technology Using gm/ID Method

In this work, an analog front-end (AFE) circuit for an electrocardiogram (ECG) detection system has been designed, implemented, and investigated in an industry-standard Cadence simulation framework using an advanced technology node of 45 nm. The AFE consists of an instrumentation amplifier, a Butterworth band-pass filter (with fifth-order low-pass and second-order high-pass sections), and a second-order notch filter—all are based on two-stage, Miller-compensated operational transconductance amplifiers (OTA). The OTAs have been designed employing the gm/ID methodology. Both the pre-layout and post-layout simulation are carried out. The layout consumes an area of 0.00628 mm2 without the resistors and capacitors. Analysis of various simulation results are carried out for the proposed AFE. The circuit demonstrates a post-layout bandwidth of 239 Hz, with a variable gain between 44 and 58 dB, a notch depth of −56.4 dB at 50.1 Hz, a total harmonic distortion (THD) of −59.65 dB (less than 1%), an input-referred noise spectral density of <34 μVrms/Hz at the pass-band, a dynamic range of 52.71 dB, and a total power consumption of 10.88 μW with a supply of ±0.6 V. Hence, the AFE exhibits the promise of high-quality signal acquisition capability required for portable ECG detection systems in modern healthcare.

A single-IC realizable, electronically tunable, OTA-based full-wave rectifier with simultaneous positive and negative outputs

A new voltage-mode full-wave rectifier (FWR) is proposed in this study. The proposed FWR employs two single-output operational transconductance amplifiers (OTAs), four diodes, and two grounded resistors. It has high input impedance and does not need any extra bias current or voltage sources. It simultaneously provides positive and negative rectified output signals over separate output terminals. The amplitudes of both output signals can be adjusted by varying the resistor values or the transconductance (gm) values of the OTAs. It does not include any floating passive elements, so it is suitable for integrated circuit (IC) implementations. The proposed FWR can be implemented by using a single commercially available IC such as LM13700. However, the proposed FWR has a single matching condition for gm values of the OTAs. Several simulation and experimental test results are added to confirm the theory and show the operability of the proposed circuit.

Localized Stress Effects on the Single Event Effects Sensitivity of Microelectronics

Understanding the single event effects (SEE) sensitivity of microelectronic devices and circuits is essential for long-term mission success in ionizing radiation environments. SEEs occur when a single ionizing particle strikes a device with enough energy to cause anomalous malfunction or even a catastrophic failure event. It is conventionally viewed as an electrical phenomenon, whereas this study investigates the possible role of multi-physics. Specifically, we show that localized mechanical stress in electronic devices significantly impacts the degree of SEE sensitivity. We present a technique that indirectly maps both electrical and mechanical field localization to spatially map SEE sensitivity without any need for radiation test sources. It is demonstrated on the operational amplifier LM124 under both pristine and stressed conditions. To validate our hypothesis, our experimental results are compared with those obtained from the well-established pulsed laser SEE technique. Excellent agreement between these results supports our hypothesis that SEE susceptibility may have fundamental roots in both electrical and mechanical fields. Therefore, the ability to map the localizations in these fields may indirectly map the SEE sensitivity of large area electronics, which is very expensive in time and resources.

High-gain ultra-wideband bismuth-doped fiber amplifier operating in the O + E + S band.

We present a double-pass bismuth (Bi)-doped fiber amplifier (BDFA) providing high-gain wideband amplification from 1330 to 1480 nm. A peak gain of 38 dB with 4.7 dB noise figure (NF) was obtained at 1420 nm for a -23 dBm input signal, with >20 dB gain from 1335 to 1475 nm. We achieved 30 and 21.5 dB peak gains with 122 nm (1341-1463 nm) and 140 nm (1333-1473 nm) 6 dB-gain bandwidth for -10 and 0 dBm input signal, respectively. For a 0 dBm signal, the power conversion efficiency (PCE) reached 23.7%, and the in-band optical-signal-to-noise ratio (OSNR) across the wideband BDFA was >44 dB. Also, the absorption and luminescence characteristics have been studied for different Bi-doped phosphosilicate fibers (BPSFs) fabricated in-house.

CMOS operational amplifier design for industrial and biopotential applications: Comprehensive review and circuit implementation

This paper provides a detailed exploration of CMOS operational amplifiers (Op-Amps) aimed at enhancing understanding of their development, design, and application. To achieve this, a comprehensive examination of the common characteristics, parameters, and bibliographic reviews of Op-Amps, distinguishing among various chosen operational amplifiers. A comprehensive bibliographic review of the operational amplifier's keywords between 2008 and 2018 has also been conducted. A bibliometric analysis of 4997 documents from the Web of Science (WOS) Collection is conducted using VOSviewer software. Furthermore, an analysis and comparison of these Op-Amps across functional aspects relevant to industrial and biomedical applications, emphasising the salient characteristics of each technique. After the survey, a novel Op-Amp design is proposed, incorporating a differential amplifier at the first stage, along with a compensating capacitor and a high gain stage. The biasing circuitry is replaced with an active load resistor (MOS transistor), simplifying layout design, and reducing the amplifier's area and power consumption compared to traditional two-stage designs. The power source for this design is 3.3 V. This designed operational amplifier achieved a gain of 62.9449 dB, a high CMRR of 92.8079 dB, and a unity gain bandwidth of 33 MHz, and the optimised layout area is 0.001476 μm2. The proposed circuit was designed and simulated utilising the Cadence Virtuoso 180 nm CMOS process. The simulation results show that the desired criteria have been met. Additionally, the challenges and future possibilities in analog circuits, laying the groundwork for research in both analogue and digital circuits to tackle complex real-world issues have been addressed.

Front-end electronics development of large-area SiPM arrays for high-precision single-photon time measurement

TRopIcal DEep-sea Neutrino Telescope (TRIDENT) plans to incorporate silicon photomultipliers (SiPMs) with superior time resolution in addition to photomultiplier tubes (PMTs) into its detection units, namely hybrid Digital Optical Modules (hDOMs), to improve its angular resolution. However, the time resolution significantly degrades for large-area SiPMs due to the large detector capacitance, posing significant challenges for the readout electronics of SiPMs in hDOM. We analyzed the influences of series and parallel connections when constructing a large-area SiPM array and designed a series-parallel connection SiPM array with differential output. We also designed a high-speed pre-amplifier based on transformers (MABA-007159) and radio frequency amplifiers (BGA2803), and an analog multi-channel summing circuit based on operational amplifiers (LMH6629). We measured the single photon time resolution (SPTR) of a 4 × 4 SiPM (Hamamatsu S13360-3050PE) array (12 × 12 mm2) of approximately 300 ps FWHM. This front-end readout design enables the large-area SiPM array to achieve high-precision single photon time measurement in one readout channel.

A novel gain boost and slew rate enhanced CMOTA

Abstract The design of a novel current mirror operational transconductance amplifier is proposed to address the issues of low gain and limited swing rate under conditions of low voltage and power consumption. In order to improve the gain and swing rate of the amplifier, the increase and lift technology and swing rate increase technology are introduced to the traditional op-amp Simulation and verification based on 0.18 μm BCD process and candence. The results show that under 10 pF load capacitance, the gain is increased by 42 dB and the swing rate is increased by 130 times compared with the conventional transconductance op amp.

A high-gain high-drive operational amplifier

Abstract This paper presents a high-gain, high-drive operational amplifier based on the 0.18 μm technology. The first stage employs a current-reuse common-source common-gate structure to enhance gain, while the second stage utilizes a transconductance-enhanced push-pull output stage. This design achieves high-drive performance while retaining a high gain. Simulation using Cadence software demonstrates that, under a 5 V power supply voltage, the amplifier exhibits a low-frequency gain of 120 dB, with output sink and source current capabilities reaching 17.7 mA and 2.53 mA, respectively.

A 12-bit 2.5-bit/phase two-stage cyclic ADC with phase scaling and low-power Sub-ADC for CMOS image sensor

This paper proposed a 12-bit 2.5-bit/phase two-stage cyclic Analog-to-Digital Converter (ADC) with phase scaling and low-power Sub-ADC for CMOS image sensors. The phase scaling technique reduces the performance requirements of operational amplifiers for the cyclic ADC. Furthermore, the Sub-ADC architecture based on tri-state comparators reduces the power consumption of the Sub-ADC. The implemented cyclic ADC is designed with 110 nm process. Simulation results demonstrate that the proposed 12-bit, 1 MS/s, 2.5-bit/phase, two-stage cyclic ADC achieves an effective number of bits (ENOB) of 11.4-bit with a power consumption of 0.185 mW per column. Compared with the traditional fixed phase structure, the power consumption of the phase scaling structure is reduced by 22.3 %. Additionally, the cyclic ADC attains a Figure of Merit (FoM) of 68.5fJ/step.

P‐81: Multimodal Intelligent Display Backplane Blocks

The display of the future is multimodal, integrating optical sensors, RFID antennas, ultrasound transducers, etc. The sensors produce a large amount of redundant data, which should be preprocessed on the substrate, ideally on the backpanel. Control gates and select and data drivers need to be more configurable and partitionable to create operational flexibility. This paper presents various circuit blocks for processing and control, including operational amplifiers, high‐resolution analog‐to‐digital converters, a microprocessor, DC‐DC converters, and high resolution sensor pixel array architectures. Moreover, the performance of the basic building blocks is compared in LTPS and IGZO technology.

P‐71: Analysis of Bright, Vertical, Chain‐Like Spot Occurrence on Mobile OLED Screen Due to the Electromagnetic Interference of Nearby GSM Device

Electromagnetic Interference (EMI) plays a significant role on degraded image quality under specific operating conditions. During our product characterizations, we analyzed an event that shows bright vertical chain‐like spots on mobile Organic Light‐emitting Diode (OLED) display due to the transmit operation of Global System for Mobile (GSM) phone nearby the device under test (DUT). The cause of the event is laid out as follows. The transmitted Radio Frequency (RF) power travels through Flexible Printed Circuit (FPC) to Display Driver Integrated Circuit (DDIC). Then the transistors respond to RF power as unintended RF diodes, which generate unexpected Direct Current (DC) voltage, which pushes the panel‐driving buffer Operational Amplifier's (OPAMP) output drifted.

Leveraging Concentration Imbalance-Driven DNA Circuit as an Operational Amplifier to Enhance the Sensitivity of Hepatitis B Virus DNA Detection with Hybridization-Responsive DNA-Templated Silver Nanoclusters

Leveraging Concentration Imbalance-Driven DNA Circuit as an Operational Amplifier to Enhance the Sensitivity of Hepatitis B Virus DNA Detection with Hybridization-Responsive DNA-Templated Silver Nanoclusters

Automatic Power Factor Compensation (APFC) for Industrial Power Use to Minimize Penalty

Abstract: In this proposed system, two zero crossing detectors are used for detecting zero crossing of voltage and current. The project is designed to minimize penalty for industrial units using automatic power factor correction unit. The microcontroller used in this project belongs to 8051 family. The time lag between the zero-voltage pulse and zero-current pulse is duly generated by suitable operational amplifier circuits in comparator mode is fed to two interrupt pins of a microcontroller. The program takes over to actuate appropriate number of relays from its output to bring shunt capacitors into load circuit to get the power factor till it reaches near unity. The capacitor bank and relays are interfaced to the microcontroller using a relay driver. It displays time lag between the current and voltage on an LCD. Furthermore, the project can be enhanced by using thyristor control switches instead of relay control to avoid contact pitting often encountered by switching of capacitors due to high in rush current

Application of Digital Galvanometer Scanner System for CO2 Fractional Laser Safety Improvement

An analog PID controller-based galvanometer scanner is widely used by fractional laser medical equipment (FLME) to scan lasers across tissue surfaces, achieving the desired therapeutic effect. This type of driver, primarily composed of passive components and operational amplifiers, can only accept commands from the central controller of the FLME, with a simple hardware circuit-based fault diagnosis; thus, the safety of the FLME is compromised. To address these issues, the failure mechanisms of galvanometers and their impact on the safety of FLME are thoroughly analyzed first. Then, an adaptive limit protection method, a coil open circuit fault diagnosis, a communication timeout protection based on two handshakes, and a galvanometer control timeout protection are proposed, respectively, based on a digital driver platform, to supplement the deficiencies in the original fault diagnosis and protection system. This ensures the safety of the FLME. Finally, the effectiveness of the proposed strategies is validated through experiments.

Advancements in Filter Technology: Evolution and Applications

This paper explores the historical trajectory and contemporary applications of signal processing filters. From the early days of analog filters to the current digital era, the paper traces their evolution, emphasizing key developments in active RC filters, monolithic integrated op amps, and the transition to switched-capacitor and continuous-time filters. Fundamentals of analog and digital filters are outlined, distinguishing their processing of continuous-time and discrete-time signals. The classification of filters, including low-pass, high-pass, band-pass, and band-stop, is discussed with insights into their specific applications. The paper delves into crucial applications in audio processing, video processing, communication systems, power management, and sensor signal processing, showcasing filters' pivotal role in enhancing signal quality across diverse fields. Addressing emerging technologies, the paper highlights adaptive and deep learning filters, projecting the future trends in filter technology. It anticipates developments in analog integrated filters, emphasizing the growing significance of integrated circuits technology. This comprehensive review aims to deepen readers' understanding and inspire continued innovation in signal processing.

A New CMOS FTFNDITA Implementation and Its Application

ABSTRACT This research article presents a new design of a CMOS analog building block, termed a Four Terminal Floating Nullor Differential Input Transconductance Amplifier (FTFNDITA). This new analog building block can operate up to the MHz range and offers low-power dissipation circuitry. The proposed FTFNDITA works with ± 1.65 V power supply. Moreover, a ICs-based FTFNDITA is also developed using an off-self commercially available Current Feedback Operational Amplifier (CFOA) as IC AD844 and Operational Transconductance Amplifier (OTA) as IC LM13700 or IC CA3080. To extend the application perspective of the proposed FTFNDITA blocks, a few fundamental analog signal processing circuits like the design of Floating Inductor Simulator (FIS), First-Order Low-Pass Filter (FLPF), Floating Capacitance Multiplier (FCM), and its extension for active filter design, are incorporated. In addition, a non-ideality investigation is also performed to test the deviation between the ideal and practical design. Finally, PSPICE and experimental verifications are observed to validate the functionality of FTFNDITA.

Development and characterization of a dedicated dose monitor for ultrahigh-dose-rate scanned carbon-ion beams

The current monochromatic beam mode (i.e., uHDR irradiation mode) of the scanned carbon-ion beam lacks a dedicated dose monitor, making the beam control challenging. We developed and characterized a dedicated dose monitor for uHDR-scanned carbon-ion beams. Furthermore, a simple measurable dose rate (dose rate per spot (DRspot)) was suggested by using the developed dose monitor and experimentally validating quantities relevant to the uHDR scanned carbon-ion beam. A large plane-parallel ionization chamber (IC) with a smaller electrode spacing was used to reduce uHDR recombination effects, and a dedicated operational amplifier was manufactured for the uHDR-scanned carbon-ion beam. The dose linearity of the IC was within ± 1% in the range of 1.8–12.3 Gy. The spatial inhomogeneity of the dose response of the IC was ± 0.38% inside the ± 40-mm detector area, and a systematic deviation of approximately 2% was measured at the edge of the detector. uHDR irradiation with beam scanning was tested and verified for different doses at the corresponding dose rates (in terms of both the average dose rate and DRspot). We confirmed that the dose monitor can highlight the characteristics (i.e., dose, dose rate, and dose profile) of uHDR-scanned carbon-ion beams at several dose levels in the monochromatic beam mode.