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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.

This paper presents the design of an ultra-low power, ultra-low-noise paralle active load operational transconductance amplifier (PAL-OTA) in a 65 nm CMOS process, dissipating only 1.6 μW. The proposed design employs a singlestage differential pair configuration with a parallel active load, operating at a 0.8V supply voltage. The parallel active load increases the effective gate width, reducing flicker noise and contributing to the overall noise performance of the OTA, achieving an exceptionally low input-referred noise of 179.8 pV/√Hz. Simulation results demonstrate that the design achieves a favourable trade-off between power consumption, noise performance, and gain. The use of an active load significantly enhances the amplifier’s stability, increasing the phase margin from 80° to 90°. This makes the OTA particularly well-suited for ultra-low power analog systems.

The International Roadmap for Devices and Systems (IRDS) forecasts that, for silicon-based metal–oxide–semiconductor (MOS) field-effect transistors (FETs), the scaling of the gate length will stop at 12 nm and the ultimate supply voltage will not decrease to less than 0.6 V (ref.  1 ). This defines the final integration density and power consumption at the end of the scaling process for silicon-based chips. In recent years, two-dimensional (2D) layered semiconductors with atom-scale thicknesses have been explored as potential channel materials to support further miniaturization and integrated electronics. However, so far, no 2D semiconductor-based FETs have exhibited performances that can surpass state-of-the-art silicon FETs. Here we report a FET with 2D indium selenide (InSe) with high thermal velocity as channel material that operates at 0.5 V and achieves record high transconductance of 6 mS μm −1 and a room-temperature ballistic ratio in the saturation region of 83%, surpassing those of any reported silicon FETs. An yttrium-doping-induced phase-transition method is developed for making ohmic contacts with InSe and the InSe FET is scaled down to 10 nm in channel length. Our InSe FETs can effectively suppress short-channel effects with a low subthreshold swing (SS) of 75 mV per decade and drain-induced barrier lowering (DIBL) of 22 mV V −1 . Furthermore, low contact resistance of 62 Ω μm is reliably extracted in 10-nm ballistic InSe FETs, leading to a smaller intrinsic delay and much lower energy-delay product (EDP) than the predicted silicon limit. A two-dimensional field-effect transistor made of indium selenide is shown to outperform state-of-the-art silicon-based transistors, operating at lower supply voltage and achieving record high transconductance and ballistic ratio.

In this research article, a grounded resistorless meminductor emulator is proposed. The proposed emulator uses one voltage differencing transconductance amplifier (VDTA) and one operational transconductance amplifier (OTA) with corresponding grounded capacitances. It can be operated in both decremental and incremental configurations. The comparison of the proposed emulator with available literature is also included. The proposed meminductor emulator circuit has been designed and simulated in Cadence Virtuoso Analog Design Environment using 180 nm gdpk technology parameters. Moreover, the application of the proposed emulator as a second-order bandpass filter (BPF) is also given. The simulation results agree well with the theory and confirm the meminductor functionality.

In this paper, we present a novel operational transconductance amplifier (OTA) topology based on a dual-path body-driven input stage that exploits a body-driven current mirror-active load and targets ultra-low-power (ULP) and ultra-low-voltage (ULV) applications, such as IoT or biomedical devices. The proposed OTA exhibits only one high-impedance node, and can therefore be compensated at the output stage, thus not requiring Miller compensation. The input stage ensures rail-to-rail input common-mode range, whereas the gate-driven output stage ensures both a high open-loop gain and an enhanced slew rate. The proposed amplifier was designed in an STMicroelectronics 130 nm CMOS process with a nominal supply voltage of only 0.3 V, and it achieved very good values for both the small-signal and large-signal Figures of Merit. Extensive PVT (process, supply voltage, and temperature) and mismatch simulations are reported to prove the robustness of the proposed amplifier.

Molecular binding to receptors on the surface of field-effect transistors (FETs) can be sensed through changes in transconductance. However, the saline solutions typically used with biomolecules create an electrical double layer that masks any events that occur within about 1 nanometer from the surface. Nakatsuka et al. overcame this limitation by using binding to large, negatively charged DNA stem loop structures that, upon ligand binding, cause conformational changes that can be sensed with an FET, even in solutions with high ionic strength. The authors demonstrate the sensing of charged molecules such as dopamine in artificial cerebrospinal fluid as well as neutral molecules such as glucose and zwitterion molecules like sphingosine-1-phosphate. Science , this issue p. 319 Large conformational changes induced in charged DNA stem-loop receptors can be sensed in high–ionic strength solutions. Detection of analytes by means of field-effect transistors bearing ligand-specific receptors is fundamentally limited by the shielding created by the electrical double layer (the “Debye length” limitation). We detected small molecules under physiological high–ionic strength conditions by modifying printed ultrathin metal-oxide field-effect transistor arrays with deoxyribonucleotide aptamers selected to bind their targets adaptively. Target-induced conformational changes of negatively charged aptamer phosphodiester backbones in close proximity to semiconductor channels gated conductance in physiological buffers, resulting in highly sensitive detection. Sensing of charged and electroneutral targets (serotonin, dopamine, glucose, and sphingosine-1-phosphate) was enabled by specifically isolated aptameric stem-loop receptors.

This paper presents a new low-voltage versatile mixed-mode filter which uses a multiple-input/output differential difference transconductance amplifier (MIMO-DDTA). The multiple-input of the DDTA is realized using a multiple-input bulk-driven MOS transistor (MI-BD-MOST) technique to maintain a single differential pair, thereby achieving simple structure with minimal power consumption. In a single topology, the proposed filter can provide five standard filtering functions (low-pass, high-pass, band-pass, band-stop, and all-pass) in four modes: voltage (VM), current (CM), transadmittance (TAM), and transimpedance (TIM). This provides the full capability of a mixed-mode filter (i.e., twenty filter functions). Moreover, the VM filter offers high-input and low-output impedances and the CM filter offers high-output impedance; therefore, no buffer circuit is needed. The natural frequency of all filtering functions can be electronically controlled by a setting current. The voltage supply is 0.5 V and for a 4 nA setting current, the power consumption of the filter was 281 nW. The filter is suitable for low-frequency biomedical and sensor applications that require extremely low supply voltages and nano-watt power consumption. For the VM low-pass filter, the dynamic range was 58.23 dB @ 1% total harmonic distortion. The proposed filter was designed and simulated in the Cadence Virtuoso System Design Platform using the 0.18 µm TSMC CMOS technology.

Owing to the mixed electron/hole and ion transport in the aqueous environment, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)-based organic electrochemical transistor has been regarded as one of the most promising device platforms for bioelectronics. Nonetheless, there exist very few in-depth studies on how intrinsic channel material properties affect their performance and long-term stability in aqueous environments. Herein, we investigated the correlation among film microstructural crystallinity/composition, device performance, and aqueous stability in poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) films. The highly organized anisotropic ordering in crystallized conducting polymer films led to remarkable device characteristics such as large transconductance (∼20 mS), extraordinary volumetric capacitance (113 F·cm −3 ), and unprecedentedly high [ μC * ] value (∼490 F·cm −1 V −1 s −1 ). Simultaneously, minimized poly(styrenesulfonate) residues in the crystallized film substantially afforded marginal film swelling and robust operational stability even after >20-day water immersion, >2000-time repeated on-off switching, or high-temperature/pressure sterilization. We expect that the present study will contribute to the development of long-term stable implantable bioelectronics for neural recording/stimulation. The lack of understanding of mixed transport in ion-permeable conjugated polymer films hinders the advance of organic electrochemical transistors for bioelectronics. Here, the authors elucidate the structure-property-performance relationships for conventional and crystallized PEDOT:PSS films.

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.

The proposed work focuses on the design of a current-reused biomedical amplifier; it is a microwatt-level electrocardiogram (ECG) analog circuit design that addresses low power consumption and noise efficiency. As implantable devices require unobtrusiveness and longevity, the current reuse technique in this circuit effectively enhances power and noise efficiencies. Using 90 nm technology enables efficient circuit implementation, yielding promising simulation results. At 100 Hz, the noise performance reaches 62.095 nV/√Hz, while the power consumption is only 8.3797 µW. These advancements are pivotal for next-generation implantable devices, ensuring reliable operation and reducing frequent battery replacements, improving patient convenience. Moreover, the high noise efficiency ensures that ECG signals are captured with high fidelity, crucial for accurate monitoring and diagnosis. This research addresses the challenges in implantable ECG analog circuit design and sets a benchmark for future developments. The techniques employed can be adapted for other bio signal monitoring devices, broadening the impact on healthcare technology. Ultimately, this advancement contributes to more efficient, reliable, and long-lasting medical devices, enhancing patient monitoring and healthcare on a broader scale.