Gain-bandwidth Product Research Articles

Balanced travelling-wave parametric amplifiers for practical applications

Abstract The development of superconducting travelling-wave parametric amplifiers (TWPAs) over the past decade has highlighted their potential as low-noise amplifiers for use in fundamental physics experiments and industrial applications. However, practical challenges, including signal-idler contamination, complex pump injection and cancellation, impedance mismatch, and the reciprocal nature of the device, have made it challenging to deploy TWPAs in real-world applications. In this paper, we introduce an innovative solution to these issues through phase-controlled balanced-TWPA architectures. These architectures involve placing two TWPAs in parallel between a pair of broadband couplers. By carefully controlling the phases of the tones propagating along the TWPAs, we can effectively separate the signal and idler tones, as well as the pump(s), using a straightforward injection and cancellation mechanism. The balanced-TWPA architecture offers versatility and flexibility, as it can be reconfigured either intrinsically or externally to suit different application needs. In this manuscript, we provide a comprehensive discussion of the working principles of the balanced-TWPA, including various configurations designed to meet diverse application requirements. We also present the expected gain-bandwidth products in comparison to traditional TWPAs and conduct tolerance analysis to demonstrate the feasibility and advantages of the balanced-TWPA architecture. By addressing the practical challenges associated with TWPAs, the balanced-TWPA architecture represents a promising advancement in the field, offering a more practical and adaptable solution for a wide range of applications.

Performance and reliability assessment of source work function engineered charge plasma based Ti/HfO2/Al2O3/Ge, double gate TFET

The Tunnel Field Effect Transistor (TFET) often suffers from low ON current (I ON), charge traps, and thermal variability, which limits its performance and reliability. To address these issues, the source work function engineered Ge Charge Plasma Double Gate Tunnel Field Effect Transistor (CP-DGTFET) device structure with HfO2/Al2O3 bilayer gate dielectric is designed and investigated using numerical TCAD simulations. The proposed Ti/HfO2/Al2O3/Ge CP-DGTFET device structure showed excellent DC characteristics with exceptional I ON, I ON/I OFF ratio, and minimal sub-threshold swing (S) of ∼3.04 × 10−4 A μm−1, ∼1.2 × 1010, and ∼3.4 mV/dec, respectively. Furthermore, the device’s analog characteristics displayed good transconductance, cut-off frequency, and gain bandwidth product of ∼0.75 mS/μm, ∼0.97 THz, and ∼102 GHz, respectively. Moreover, the charge trap exploration divulges that positive ITCs can enhance device performance, whereas negative ITCs can adversely impact the electrical characteristics of CP-DGTFET. Additionally, the temperature-dependent analysis showed that the OFF-state leakage current increases from ∼1.7 × 10−15 A μm−1 to 2.4 × 10−10 A μm−1 with temperature fluctuations from 275 K to 375 K. Overall, the work function-engineered CP-based Ti/HfO2/Al2O3/Ge DGTFET device structure shows great potential for improving the performance and reliability of Ge TFET technology.

Electrically Small, Near-Field Resonant Parasitic Monopole Antenna With Large Gain-Bandwidth Product and Harmonic Modes Migration

Electrically Small, Near-Field Resonant Parasitic Monopole Antenna With Large Gain-Bandwidth Product and Harmonic Modes Migration

Performance Enhancement of Ge/Si Avalanche Photodetector by Specific Sidewall Passivation Using Remote Oxygen Plasma Treatment

Abstract We report on an obvious performance enhancement of separated absorption charger-layer multiplication (SACM) Ge/Si avalanche photodetector with the sidewalls passivated by low temperature remote oxygen plasma (ROP) treatment. The dangling bonds on the Ge surface can be efficiently passivated by the formation of ideal Ge/GeO2 interface. With ROP passivation, the leakage current of device shows a (3~4)-fold decrease at 300 K, resulting in a dark current (Idark) of 3.5×10-6 A at 90% avalanche voltage (Vbr) and 3.4×10-7 A at punch-through voltage (Vpuhch-through) for the 26-μm-diameter device. At 200 K, more than 10-fold decrease is demonstrated, and the passivation mechanism is revealed. Moreover, a multiplication gain of 94 is obtained under 1550 nm illumination. The device with ROP passivation shows an improved gain bandwidth product (GBP) of 190 GHz. The enhanced high frequency response of the device with ROP passivation can be ascribed to the relief of the retarding effect caused by the interface state on the sidewalls. An opening eye diagram at 28 Gbps without using any trans-impedance amplifier (TIA) is demonstrated, indicating a reliable device transmission performance.

Theoretical proposal for a broadband on-chip multistage quantum amplifier

Abstract A broadband on-chip multistage quantum amplifier (MQA) for reading out multiple superconducting qubits is proposed. The bandwidth of quantum amplifier is enhanced by concatenating amplifiers with modular nonreciprocal elements, which are superconducting isolators and circulators based on tunable inductor bridge. The circuit model of MQA is built and simulated. The variation of bandwidth, gain and Gain-bandwidth Product (GBP) of MQA with the number of stages and bandpass of the constitutive amplifiers are simulated. It is revealed that the bandwidth can be as large as ∼ 3.2 GHz with a gain of 20 dB at 4-8 GHz frequency range. For a 4-stage MQA composed of four quantum amplifiers with 20 dB gain and 0.3 GHz BW-pass, the bandwidth is 2.14 GHz at 20 dB gain, which is quite cost-efficient. Due to its non-reciprocity, MQA can effectively prevent signals from reflecting to quantum processors. In addition, MQA breaks the limitation of GBP and is easy to integrate with superconducting circuits. The MQA would play a crucial role in the high-fidelity readout of multiple qubits in large-scale superconducting quantum computers.

Adaptive composite bandwidth and automatic gain control receiver for 6G wireless optical communication

The advent of 6G communication promises a transformative leap in wireless connectivity, ushering in an era of unprecedented data rates, ultra-low latency, and pervasive connectivity. To harness the full potential of 6G networks, it is imperative to address the unique challenges posed by evolving communication environments. In this context, we present a novel framework that integrates Adaptive Composite Bandwidth and Automatic Gain Control techniques into the 6G communication paradigm. Optical wireless receivers experience large input current difference due to the large transmitted power, noise from ambient light and the varying efficiencies of different photodiode receivers. With its large dynamic range of μA to mA, transimpedance amplifiers are suitable to handle photodiode efficiency with a large dynamic range. The receiver design proposed in this article incorporates two characteristic parameter adjustments, namely, bandwidth and automatic gain. By adjusting the bandwidth the signal-to-noise ratio of the incoming signal is automatically controlled. By controlling the bandwidth, the unwanted noise is reduced and amplifier output is liable to low noise and enhances the dynamic range without extra filtering. The automatic gain control adapts its gain based on slight change in the input signal at the receiver front-end. This optimization technique ensures low photo-detection and amplification noise to achieve better quality of service. The results indicate that the bootstrap transimpedance amplifier gain is around 53.3 dB and frequency cut-off at 109.7 MHz. Thus, when gain control capacitance is varied between 50 pF to 1 nF, the bandwidth adjustment falls in the range 7.5–104.1 MHz, and the amplifier’s second stage gain becomes 10.4 dB. The overall gain of the proposed configuration with automatic gain control integrated into the transimpedance amplifier increases up to 31.1 dB, while the bandwidth increases from 9.4 to 60.7 MHz. Consequently, the gain bandwidth product is optimized from 10.4 to 31.1 dB. The main contribution of this work is optimizing the product by selecting a capacitance value within the given range that maximizes the gain-bandwidth product. This optimization paradigm is predicated on identifying a capacitance value that minimizes the gain-bandwidth product, thereby effectuating effective noise mitigation. This proposed framework embodies a significant contribution to the domain of 6G communications, heralding a new epoch in the optimization of wireless connectivity through the strategic integration of adaptive bandwidth and automatic gain control mechanism.

Unveiling the influence of temperature and interface traps on the performance of source-all-around vertical TFET

This study investigates the electrical performance of a line-tunneling based source-all-around vertical Tunnel Field-Effect Transistor (SAA-VTFET) under diverse temperature and trap charge conditions. The proposed device achieves remarkable performance improvements across DC and AC parameters by employing strategically engineered III-V semiconductors and a wide source-channel tunneling heterojunction. Key metrics like on-state current (ION = 6.35 × 10−5 A/μm), off-state current (IOFF = 3.17 × 10−17 A/μm), threshold voltage (VT = ⁓0.18V), subthreshold swing (SSavg = ⁓7 mV/dec), transconductance (gm = 0.16 mS), cut-off frequency (fc = ⁓0.42 THz), gain bandwidth product (GBP), delay (τ), and various capacitances are thoroughly analyzed. Sentaurus TCAD 3D simulations employed in this study demonstrate the promising future of SAA-VTFETs in low-power and high-speed electronics.

Design, optimization, and performance analysis of GaP/Si heterojunction Fin-TFET with MoS2 nanoribbon channel

This article presents the design and optimization of GaP/Si heterojunction Fin-TFET with a MoS2 channel. The elevated fin structure, coupled with ultrathin MoS2 layers and the tuneable bandgap properties of MoS2 material, significantly enhances gate control over the channel and improves device performance. Additionally, the GaP/Si heterojunction with a heavily doped n-type source pocket leads to a narrow barrier junction, promoting Band-to-Band Tunneling (BTBT). The optimized Fin-TFET boasts exceptional electrical characteristics: a high ON-current (7.72 × 10−5 A/μm), an ultra-low OFF-current (4.16 × 10−17 A/μm), and leading to an outstanding ION/IOFF ratio (7.23 × 1012). Furthermore, the device demonstrates a steep subthreshold slope (SS) of 6 mV/dec (point) and 16.8 mV/dec (average), alongside impressive analog performance with a transconductance (gm) of 2.75 × 10−4 S, a cut-off frequency (fc) of 1.3 × 1012 THz, and a gain-bandwidth product (GBP) of 0.17 × 1012 THz. The entire analysis was conducted utilizing the Sentaurus TCAD-3D simulation tool.

Avalanche photodiode with ultrahigh gain–bandwidth product of 1,033 GHz

Avalanche photodiode with ultrahigh gain–bandwidth product of 1,033 GHz

Plasmonic tuning of nano-antennas for super-gain light amplification

Nanoscale conductive materials are often used for inducing localized free electron oscillations known as plasmons. This is due to their high electronic excitability under optical irradiation owing to their super-small volume. Recently, plasmons have been of interest for enhancing the gain-bandwidth product of optical amplifiers. There are currently two well-established mechanisms for light amplification. The first one is via stimulated emission of radiation (lasers) using a given energy source and often an optical feedback mechanism. The second one is based on the nonlinear coupling of a low-intensity input wave and a high-intensity pump wave for energy exchange (parametric amplifiers). Both techniques have shortcomings. Lasers have a small operation bandwidth and offer a limited gain, but require moderate energy pumping to operate. Whereas optical parametric amplifiers (OPAs) offer a high operation bandwidth along with a much higher optical gain, with the drawback of requiring intense pumping to be functional. The aim of this paper is to introduce a technique that combines the advantages and eliminates the drawbacks of both techniques in the nanoscale to allow for a better amplification performance in integrated optical devices. This is achieved by inducing a plasmonic chirp in conductive nanomaterials a.k.a nano-antennas, which enables the confinement of an enormous electric energy density that can be coupled to an input beam for amplification. Using the Finite Difference Time Domain numerical-method with the material parameters of well-known semiconductors, intramaterial condensation of electric energy density is observed in semiconductor nano-antennas for certain plasmonic chirp-frequencies which enables broadband high-gain optical amplification based on free-electron oscillations that is promising for small-scale optical devices requiring a high gain-bandwidth product. The results are in good agreement with semiempirical data.

Improvement of C-shaped pocket TFET with sandwiched drain for ambipolar performance and analog/RF performance

A novel structure of tunneling field effect transistor device (CSP-SD-TFET) is proposed, which adds a sandwiched drain to the C-shaped pocket TFET (CSP-TFET). This structure can increase the resistance of the drain, share the lateral electric field at the tunneling junction between the channel and the drain, reduce the lateral electric field at the tunneling junction, and suppress the generation of ambipolar current. The DC and analog/RF characteristics of CSP-SD-TFET are simulated and analyzed by Sentaurus TCAD, and the sandwiched structure parameters of the drain are optimized. The results show that the sandwiched drain structure suppresses the ambipolar current and on-state current, so the parameters of the sandwiched drain structure need to be a compromise between low ambipolar current and high on-state current. The optimized CSP-SD-TFET device has good DC characteristics, such as low average subthreshold swing SSavg (12.2mV/dec), high on/off current ratio Ion/Ioff (2.5 × 1011), high on-state current Ion (9.02 × 10−4 A/μm) and low ambipolar current Iamb (5.41 × 10−17A/μm). The RF performance of the CSP-SD-TFET, such as the cut-off frequency fT (1 × 1011 Hz) and gain-bandwidth product GBP (5.66 × 1010 Hz), are improved. It can be seen that the CSP-SD-TFET device not only has good DC characteristics but also improves analog/RF characteristics.

Achievement of non-charge layer InGaAs/Si avalanche photodiodes by introducing a groove ring at the bonding interface

The avalanche photodiode (APD) is a prototypical example of a fast and high-gain detector, particularly in the infrared band, where it plays a crucial role in both military and civil optoelectronic devices. The combination of indium gallium arsenide (InGaAs) and silicon (Si) offers an ideal solution for achieving high-performance APDs. For traditional InGaAs/Si APDs, the incorporation of a p-Si charge modulation layer between InGaAs and Si is necessary for electric field modulation. This ensures that a high electric field is maintained in the multiplication layer while keeping it low in the absorption layer. However, the preparation of the p-Si charge modulation layer necessitates a tedious and expensive ion implantation process. Besides, the ion implantation process can also lead to material surface contamination that significantly affects the performance of the device. In this paper, an InGaAs/Si APD without the charge layer is reported. This approach is based on semiconductor direct bonding technology, wherein a groove ring is introduced into the bonding interface to replace the charge layer to regulate the electric field distribution. The electric field of the absorption layer and the multiplier layer is controlled by adjusting the number of grooved rings. By introducing 11 grooved rings into the bonding interface, we achieve a remarkable gain bandwidth product of 88.55 GHz. These findings hold significant implications for the future development of non-charge layer InGaAs/Si APDs with high-gain bandwidth products.

Integrated Circuit of a Chua's System Based on the Integral-Differential Nonlinear Resistance with Multi-Path Voltage-Controlled Oscillator.

In this paper, we present a fully integrated circuit without inductance implementing Chua's chaotic system. The circuit described in this study utilizes the SMIC 180 nm CMOS process and incorporates a multi-path voltage-controlled oscillator (VCO). The integral-differential nonlinear resistance is utilized as a variable impedance component in the circuit, constructed using discrete devices from a microelectronics standpoint. Meanwhile, the utilization of a multi-path voltage-controlled oscillator ensures the provision of an adequate oscillation frequency and a stable waveform for the chaotic circuit. The analysis focuses on the intricate and dynamic behaviors exhibited by the chaotic microelectronic circuit. The experimental findings indicate that the oscillation frequency of the VCO can be adjusted within a range of 198 MHz to 320 MHz by manipulating the applied voltage from 0 V to 1.8 V. The circuit operates within a 1.8 V environment, and exhibits power consumption, gain-bandwidth product (GBW), area, and Lyapunov exponent values of 1.0782 mW, 4.43 GHz, 0.0165 mm2, and 0.6435∼1.0012, respectively. The aforementioned circuit design demonstrates the ability to generate chaotic behavior while also possessing the benefits of low power consumption, high frequency, and a compact size.

Reduced OFF-state current and suppressed ambipolarity in a dopingless vertical TFET with dual-drain for high-frequency circuit applications

In this article, a dopingless TFET with dual-drain and reversed T-shaped channel (DLVIT-TFET) is investigated to offer improvement in ON-state current (IOn) along with the reduction in OFF-state leakage current (IOff) and in ambipolarity. The investigated device has a dual channel region which helps in improving the on-state parameters like IOn and subthreshold swing (SS) due to the extended tunneling area. The inverted T-shaped channel minimizes the charge carriers to tunnel during the off-state, thereby reducing the magnitude of IOff. The results obtained from 2D TCAD simulation show that the investigated device provides ∼1 order of improvement in IOn and ∼3 orders of improvement in IOff. Furthermore, DLVIT-TFET offers an ∼3 orders of improvement in ambipolar current (IAmb) due to a reduction in peak electric field at channel-drain interface caused by splitting of drain potential at ambipolar state. Moreover, various analog/RF parameters such as transconductance (gm), gate parasitic capacitance (Cgd, and Cgs), cut-off frequency (fTmax), gain-bandwidth product (GBP), transconductance-frequency product (TFP) and transit time (τ) are found to be improved in DLVIT-TFET compared to the conventional DL-TFET. In addition, the transient analysis of DLVIT-TFET based inverter is analyzed, which shows improvement in the parameters like propagation delay and voltage swing. Finally, reliability of the investigated device is discussed by considering the effect of interface trap charges (ITCs) and variation in ambient temperature and it is observed that DLVIT-TFET is more immune to such defects and environmental factors than the conventional one.

Influence of the Gain–Bandwidth of the Front-End Amplifier on the Performance of a QEPAS Sensor

The quartz tuning fork used as an acoustic sensor in quartz-enhanced photo-acoustic spectroscopy gas detection systems is usually read out by means of a transimpedance preamplifier based on a low-noise operational amplifier closed in a feedback loop. The gain–bandwidth product of the operational amplifier used in the circuit is a key parameter which must be properly chosen to guarantee that the circuit works as expected. Here, we demonstrate that if the value of this parameter is not sufficiently large, the response of the preamplifier exhibits a peak at a frequency which does not coincide with the series resonant frequency of the quartz tuning fork. If this peak frequency is selected for modulating the laser bias current and is also used as the reference frequency of the lock-in amplifier, a penalty results in terms of signal-to-noise ratio at the output of the QEPAS sensor. This worsens the performance of the gas sensing system in terms of ultimate detection limits. We show that this happens when the front-end preamplifier of the quartz tuning fork is based on some amplifier models that are typically used for such application, both when the integration time of the lock-in amplifier filter is long, to boost noise rejection, and when it is short, in order to comply with a relevant measurement rate.

2–26.5 GHz GaN ultra‐wideband amplifier with over 2 W output power

AbstractA 2–26.5GHz broadband amplifier monolithic microwave integrated circuit (MMIC) based on the 0.15 μm GaN high electron mobility transistor process has been developed. The broadband amplifier adopts a two‐stage distributed amplifier cascade structure, which improves the gain of the broadband amplifier. Further, the capacitive coupling is used to improve the gain bandwidth product of the power amplifier. To improve the output return loss of the wideband amplifier, a tuning stub is introduced at the output of the circuit. The on‐wafer measurement results show that the amplifier has a gain greater than 18 dB, gain flatness less than ±1.4 dB, and saturated output power >35 dBm with a >13% power added efficiency in the whole band.

Design and application of germanium based complementary TFET devices with step tunneling paths

Expanding tunneling has consistently been one of the approaches to enhance the on-state current (Ion) and performance of Tunnel Field-Effect Transistor (TFET). This paper proposes a novel structure for TFET called Step Tunneling Path TFET (STP TFET). The stepped tunneling path is achieved by preparing majority carrier channel and introducing pocket doping layers and lightly doped channel extension regions in the channel. Taking Germanium TFET as an example, the complementary structures, electrical parameters, DC and analog characteristics of STP TFET are investigated. Simulation results demonstrate that, compared to normal TFET, STP TFET exhibits significant improvements in Ion (n-TFET∼18/p-TFET∼45 times), cut-off frequency (n-TFET∼6/p-TFET∼16 times), Gain Bandwidth Product enhancement (n-TFET∼22/p-TFET∼16 times), and Transconductance Frequency Product enhancement (n-TFET∼3/p-TFET∼15 times). Furthermore, in the C-TFET inverter, the transient rise and fall times have decreased by 149 and 199 ns, respectively, while the voltage gain has increased by 6.7 times. The proposed device shows promising potential for applications in high-speed and low-power circuit designs.

A precision current sensing circuit with chopper amplifier of symmetric topology

Precision current detection is essential in smart power switches. In this paper, a current-sensing amplifier with symmetric topology is presented, which adopts the chopping technique to improve sensing accuracy. This design offers four advantages at the same time. Firstly, the rail-to-rail complementary differential pairs are achieved to obtain a full input voltage swing, and the Class AB output stage is incorporated to increase the slew rate. Secondly, symmetric topology with the current shunt source provides moderate gain enhancement without extra power consumption and further increases the gain bandwidth product. Thirdly, the chopping technique is applied to achieve a significant reduction in the amplifier's input offset without an extra low pass filter. Fourthly, the constant GM-C biasing circuit is introduced to improve the robustness of system response and current sensing accuracy under process variations. The four advantages can be substantiated through the application of a 0.5-μm BCD technology process, with multiple simulation results, including frequency responses and current sensing accuracy in process corners and temperature variations. The mismatch Monte-Carlo and noise analyses are also conducted with the chopper on or off. Chip experimental results show that the current sensing error is within ±1.6 % from 0.01 A to 3 A load current. Furthermore, multiple tests have been conducted to determine the absolute values of the input offset voltages, ranging between 20 μV and 50 μV, which is a relatively small amount to vastly improve the sensing accuracy.

Optimization of DE-QG TFET using novel CIP and DCT techniques

In this paper, two novel techniques Channel-Intermediate-Pocket (CIP) and Dual-Channel-Type (DCT) are proposed to optimize the Drain Engineered-Quadruple Gate TFET (DE-QG TFET). The proposed DCT technique is realized by making half of the channel area with lightly doped n- and the other half with the lightly doped p- channel. The CIP technique is implemented by inserting a pocket exactly at the junction of lightly doped n- &p- channel regions. Using the proposed techniques, the Ioff is reduced by ∼3.3 times (2 × 10-17 A/μm), the Iamb is reduced by a magnitude of two orders (2.39 × 10-17 A/μm) and by using the Dual-Oxide technique, the Ion is increased by 5 times (0.641 mA/μm) that of the conventional DE-QG TFET. Also, a steeper subthreshold swing (SS) of ∼57 mV/dec and one order of magnitude increase in the Ion/Ioff ratio of 3.19 × 1013 is achieved. Further, the peak overshoot voltage is suppressed by 86%, the transconductance (gm) is increased by ∼3 times (757 μA/V), and both the cut-off frequency (fT) and the Gain Bandwidth Product (GBW) are increased by ∼2.3 times (49 GHz & 5.2 GHz) respectively. The proposed device is mainly targeted towards Analog/RF applications.

Gain-Bandwidth Product Compensation Technique by 16-Unit Tail Current Control for a Radiation Tolerant Preamplifier With 0.9% Amplitude Drop up to 5 Mrad

Gain-Bandwidth Product Compensation Technique by 16-Unit Tail Current Control for a Radiation Tolerant Preamplifier With 0.9% Amplitude Drop up to 5 Mrad