Composite Transistor Research Articles

On the design of an ultra-low-power ultra-low-voltage inverter-based OTA

In this paper, an inverter-based Operational Transconductance Amplifier (OTA) is introduced. This design is tailored for applications demanding ultra-low power consumption and exceptionally reduced supply voltage. In addition to the utilization of composite transistors and forward-body-biasing, a feedforward path is also employed to enhance the voltage gain. The OTA is simulated in a 65 nm CMOS technology with a supply voltage of 0.3 V. Simulation results show a voltage gain of 42.57 dB and a power consumption of 1.06 nW.

Analog CMOS Design in Nanometer Regime

There is no doubt that the short-channel effects have affected the analysis and design of modern analog CMOS integrated circuits significantly. Thus, models that take into account these effects must be adopted in order to obtain more accurate results. In this paper, the AC small-signal low-frequency equivalent circuit of the short-channel MOSFET transistor is developed using an appropriate model. The impact of short-channel effects on the operation of basic building blocks of analog integrated circuits such as basic amplifier configurations, cascode stage, differential amplifier and composite transistor is investigated quantitatively. Additionally, the nonlinear distortion is investigated using the adopted model.

Bend‐Resistant and Energy‐Friendly GO‐PVA/PVA Polymer Electret Synaptic Transistors for Neuromorphic Computations

AbstractPolymer electret synaptic transistor is a promising three‐terminal artificial synaptic device. In this work, the electrical characteristics of the composite insulator and transistor are enhanced by modulating the concentration of the 2D nanofiller graphene oxide (GO) and the stacked film structure based on a polyvinyl alcohol (PVA) matrix. The GO‐PVA/PVA polymer electret synaptic transistors before and after dynamic/static bending exhibit typical synaptic characteristics, including short‐term plasticity, long‐term plasticity, pair‐pulse facilitation, spike‐timing‐dependent plasticity, and “learning–forgetting–relearning” features. Importantly, the device exhibits good cycling stability, uniformity and linearity in the potentiation‐depression cycling test, which is beneficial for improving the accuracy of neuromorphic computations. Also, it shows extremely low energy consumption (≈0.32 fJ). The recognition accuracy of images is simulated based on the constructed artificial neural network, which achieves 86.8% for the MNIST dataset. In addition, the devices maintain high recognition accuracy after dynamic/static bending, indicating that the devices are extremely bend‐resistant. The GO‐PVA/PVA polymer electret synaptic transistor is expected to be a potential candidate for neuromorphic computations and electronic skin.

PVF composite conductive nanofibers-based organic electrochemical transistors for lactate detection in human sweat

The detection of lactate and other bioactive molecules is of great significance in biological research, medical testing, and environmental monitoring. Organic electrochemical transistors are a kind of biosensor devices, which can convert biological signals into electrical signals. In recent years, fiber-based organic electrochemical transistors (FECTs) provide a new approach for the construction of flexible wearable biosensors, promoting greatly the development of flexible wearable electronic products. In this study, a multilayer composite electrode was first prepared by incorporating MXene and PEDOT:PSS onto electrospun oriented polyvinyl formal (PVF) nanofiber bundle, and then assembled into FECT with high sensitivity and selectivity. Meanwhile, a wearable real-time monitoring platform was built to detect the lactate concentrations in human sweat. The results showed that MXene could act as a bridge between PEDOT:PSS and PVF, and the sensing performance of PVF/MXene/PEDOT:PSS-based FECT was enhanced obviously. It had a wide linear response range of 1 nM-100 mM, a sensitivity of 0.442 NCR/decade, a quick response time of 0.5 s, a low detection concentration, an excellent reproducibility, and a superior anti-interference characteristic. Therefore, this work provided more possibilities for the development of wearable biosensor.

Rail-to-rail input/output bulk driven class AB operational amplifier with improved composite transistors

Rail-to-rail input/output bulk driven class AB operational amplifier with improved composite transistors

POWER AMPLIFIER BASED ON COMPOSITE INJECTION-VOLTAIC TRANSISTORS

The problem of high-current radio engineering devices is related to the fact that the use of high-power transistors and other semiconductor devices is limited by such a phenomenon as a secondary breakdown, in which there is a sharp decrease in the voltage on the device with simultaneous internal current lacing, and the device fails. To solve the problem of secondary breakdown, schemes have been proposed that operate stably at reverse voltage values 4-5 times higher than usual and at power dissipation 2-3 times higher than the maximum allowable power for an individual device. The problem is proposed to be solved by using composite transistors. This is the most optimal way, since passive elements are not used.

Electrical characteristics of metal–semiconductor–metal (MSM) varactors fabricated on In0.53Ga0.47As/InAs/In0.53Ga0.47As composite channel HEMT structure

In this paper, we have fabricated and characterized metal–semiconductor–metal (MSM) varactors with gate lengths ranging from 120, 180, and 290 nm on In0.53Ga0.47As/InAs/In0.53Ga0.47As composite channel high electron mobility transistor structure. We applied the buried-Pt gate technology to study the electrical characteristics of the MSM varactors depending on the gate-to-channel distance. The fabricated MSM varactors exhibited a cutoff frequency of 185 GHz for annealed varactors and 174 GHz for non-annealed varactors with L g of 120 nm, respectively. Also, non-annealed MSM varactors show an excellent capacitance ratio (=C max/C min) of 5.1 with L g of 290 nm, this is because of the longer gate-to-channel distance compared to annealed MSM varactors. The figure of merit (FOM = f 0·C max/C min) of the MSM varactors, which represents the performance of the MSM varactors, shows 451 and 438 for non-annealed and annealed devices, respectively.

Fabrication and Characterization of In0.53Ga0.47As/InAs/In0.53Ga0.47As Composite Channel Metamorphic HEMTs (mHEMTs) on a GaAs Substrate.

In this work, we successfully demonstrated In0.53Ga0.47As/InAs/In0.53Ga0.47As composite channel metamorphic high electron mobility transistors (mHEMTs) on a GaAs substrate. The fabricated mHEMTs with a 100 nm gate length exhibited excellent DC and logic characteristics such as VT = -0.13 V, gm,max = 949 mS/mm, subthreshold swing (SS) = 84 mV/dec, drain-induced barrier lowering (DIBL) = 89 mV/V, and Ion/Ioff ratio = 9.8 × 103 at a drain-source voltage (VDS) = 0.5 V. In addition, the device exhibited excellent high-frequency characteristics, such as fT/fmax = 261/304 GHz for the measured result and well-matched modeled fT/fmax = 258/309 GHz at VDS = 0.5 V, which is less power consumption compared to other material systems. These high-frequency characteristics are a well-balanced demonstration of fT and fmax in the mHEMT structure on a GaAs substrate.

A linearity enhancement technique for low-noise transconductance amplifiers in SAW-less receivers

A new linearization technique for the transconductance of MOS transistors has been proposed. In the presented method a new composite transistor has been proposed. Moreover, composite transistors with different operating points are connected in parallel to boost the transconductance and cancel the distortion of the overall structure. The superiority of the proposed technique over the previously reported methods is that it also improves the linearity for high-power input signals. A detailed analysis has been given to prove the effectiveness of the newly proposed technique. In order to verify the analysis, a Low-Noise Transconductance Amplifier has been designed exploiting the presented approach and the extensive post-layout simulation results demonstrate at least 26 dB and 7 dB improvements in IIP3 and 1-dB compression point, respectively.

Layer-by-layer assembly of composite conductive fiber-based organic electrochemical transistor for highly sensitive detection of sialic acid

A novel composites conductive fiber based on Poly(diallyldimethylammonium chloride) and multi-walled carbon nanotubes/Poly(3, 4-ethylenedioxythiophene)-Poly(styrenesulfonate) has been prepared using layer-by-layer assembly (LBL) technology. The characterization results showed the composites film was successful prepared on the cotton fiber and had flexibility, conductivity and washability. The fiber-based organic electrochemical transistors (FECTs) have been assembled by the LBL composite fiber, which exhibit an on/off ratio of 5.12*102±17.99, a peak transconductance value of 8.7 mS, a switching response time of 1.2 s, and excellent cycle stability. Bending and repetitive hand-washing cycles of fibers have no significant influence on the electrical properties of FECTs. Moreover, FECTs maintain stable electrical properties within a week. The gate electrode of the FECT was modified with 3-aminophenylboronic acid to prepare a sialic acid (SA) biosensor. The SA biosensor based on FECTs presented a sensitivity of 57.66 mV per decade, a good linear response in a wide concentration range of 1 nM-1 mM, a linear coefficient R2=0.9848. This biosensor can be successful used to detect the SA content in saliva. Most importantly, the sensor can be integrated into fabrics with no significantly change in the device performance before and after weaving, providing an efficient detection platform for wearable healthcare application.

SiC gate-controlled bipolar field effect composite transistor with polysilicon region for improving on-state current

A novel silicon carbide gate-controlled bipolar field effect composite transistor with polysilicon region (SiC GCBTP) is proposed. Different from the traditional electrode connection mode of SiC vertical diffused MOS (VDMOS), the P+ region of P-well is connected with the gate in SiC GCBTP, and the polysilicon region is added between the P+ region and the gate. By this method, additional minority carriers can be injected into the drift region at on-state, and the distribution of minority carriers in the drift region will be optimized, so the on-state current is increased. In terms of static characteristics, it has the same high breakdown voltage (811 V) as SiC VDMOS whose length of drift is 5.5 μm. The on-state current of SiC GCBTP is 2.47 × 10−3 A/μm (V G = 10 V, V D = 10 V) which is 5.7 times of that of SiC IGBT and 36.4 times of that of SiC VDMOS. In terms of dynamic characteristics, the turn-on time of SiC GCBTP is only 0.425 ns. And the turn-off time of SiC GCBTP is similar to that of SIC insulated gate bipolar transistor (IGBT), which is 114.72 ns.

A 7.6-ns Delay Subthreshold Level-Shifter Leveraging a Composite Transistor and a Voltage-Controlled Current Source

A novel level shifter (LS) circuit that uses a new low-power approach based on a parasitic capacitance voltage controlled current source is presented to minimize the propagation delay (PD) and maximize the voltage conversion range. This new scheme uses a simplified circuit including a dependent current source, a composite transistor made of three interconnected n-channel MOSFETs (TnM), one CMOS input inverter, and one CMOS output buffer to provide a fast response time. The circuit utilizes the combined action of the equivalent parasitic capacitance of the TnM, the value of which changes dynamically according to the transient value of the input voltage, and the dependent current source to shift the input signal level up from subthreshold voltage levels to +3.0 V, with minimal delay and power consumption. The LS circuit fabricated in 0.35 μm CMOS technology occupies a silicon area of only 25 μm×25 μm. The LS shows measured rising and falling PDs of, respectively, 4 and 11.2 ns. The measured results show that the presented circuit outperforms other solutions over a wide frequency range of 1 to 130 MHz. The fabricated circuit consumes a static power 31.5 pW and a dynamic power of 3.4 pJ per transition at 1 kHz, V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DDL</sub> =0.8 V, and a capacitive load of C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> =0.1 pF.

Оптимизация работы схемы электронного предохранителя с регулируемым током перегрузки

The article discusses the application of a rapid action electrical fuse with controllable overload current in the schemes of industrial and household electrical equipment. There has been found a deficiency in the basic version of the scheme. A variant of the circuit was proposed, which helps to get rid of the drawback in the basic version: if a condenser with relatively large capacity (C ≥ 100 μF) is present in the protected circuit (in the load circuit), the circuit may not reach the operating mode, because, when the condenser is on, its large charging current triggers the electronic fuse and the load remains unconnected. This situation can be avoided only if the charging current of the condenser is greatly reduced, for which a current source on a field-effect transistor VT3 and a timing circuit R10R11C1 were introduced into the circuit. As C1 is being charged, through the current source VT3 there is a smooth increase in the bias voltage at the emitter junctions of the composite transistor switch VT1VT2 with a gradual increase in its conductivity. As a result, the starting current through the capacitive load at the first moment of time turns out to be much less, and the electronic fuse enters the operating mode. The optimal relationships were found between individual elements of the circuit, their values and modes of operation, depending on the size and nature of the load, while, thanks to the use of the domestic element base, the cost of the device turned out to be minimal compared to other circuits of a similar type. The research data can be used for operation of the devices of a similar type in the household and for industrial applications.

Hemoglobin–Polyaniline Composite and Electrochemical Field Effective Transistors

A composite of hemoglobin/polyaniline was prepared. The chemical structure of this obtained composite was confirmed using infrared absorption spectroscopy measurement. The luminol reaction of the composite manifested chemical emissions from the composite. Furthermore, electrochemical transistors using the composite were created. The hemoglobin/polyaniline-based electrochemical transistor could switch to external current flow via an electrochemical reaction. The color of the transistor surface changed from green to red upon applying electrochemical potential.

Self-Biased and Supply-Voltage Scalable Inverter-Based Operational Transconductance Amplifier with Improved Composite Transistors

This paper deals with a single-stage single-ended inverter-based Operational Transconductance Amplifiers (OTA) with improved composite transistors for ultra-low-voltage supplies, while maintaining a small-area, high power-efficiency and low output signal distortion. The improved composite transistor is a combination of the conventional composite transistor and forward-body-biasing to further increase voltage gain. The impact of the proposed technique on performance is demonstrated through post-layout simulations referring to the TSMC 180 nm technology process. The proposed OTA achieves 54 dB differential voltage gain, 210 Hz gain–bandwidth product for a 10 pF capacitive load, with a power consumption of 273 pW with a 0.3 V power supply, and occupies an area of 1026 μm2. For a 0.6 V voltage supply, the proposed OTA improves its voltage gain to 73 dB, and achieves a 15 kHz gain–bandwidth product with a power consumption of 41 nW.

Conjugated polymer–zeolite hybrids for robust gas sensors: Effect of zeolite surface area on NO2 sensing ability

• Conjugated polymer–zeolite hybrids effectively adsorbs gas molecules, which improves its NO 2 sensing performance. • The NO 2 adsorbed by zeolite can exert a p-type doping as an electron acceptor, thereby inducing an increase in the on-current. • The PST-11:P3HT film exhibited the higher NO 2 responsivity and sensitivity because of its greater surface area. • The zeolites embedded in the P3HT effectively protected the polymer from oxidation by water or oxygen. The organic field-effect transistor-based gas sensors are promising next-generation gas sensors with reliably high sensitivity and broad potential for various applications, such as E-skin and portable gas sensors, because they are lightweight, mechanically flexible, and cost-effective. However, despite the high gas responsivity of organic gas sensors, they still face challenges from the device instability under ambient conditions, which lags far behind inorganic-based gas sensors. We here report the fabrication of a novel organic–inorganic hybrid gas sensor based on the hybridization of zeolite and a conjugated polymer. We incorporate zeolite materials, PST-11 and Omega, in a conjugated polymer, P3HT, matrix, which significantly improves its NO 2 sensing performance in conjunction with high responsivity and high recovery rates due to the high surface-to-volume ratio and orderly structure of two zeolites. Comparing those two zeolites, the PST-11:P3HT film, in particular, exhibited higher NO 2 responsivity and sensitivity because of its larger specific surface area than Omega. We also demonstrate that the zeolite materials embedded in the semiconductor polymer can protect the blend film from oxidation during long-term storage under ambient conditions by the zeolite’s ability to adsorb oxidizing molecules, which leads to good long-term stability of composite transistor devices under ambient atmosphere. This study demonstrates that zeolite-based materials have potential applications in organic gas sensors.

Designing a Low-Power LNA and Filter for Portable EEG Acquisition Applications

A circuit with a low-power low-noise amplifier and a Gm-C ultra-low-power filter is proposed in this paper for portable electroencephalogram (EEG) acquisition applications. The proposed circuit contains a two-stage chopper-stabilized fully recycling folded cascode (TSRFC) amplifier and a second-order continuous-time Gm-C low pass filter (LPF) with ultra-low-power consumption. The noise and input offset are reduced using the chopper-stabilized technique. A two-stage amplifier that consists of composite transistors and a recycling structure is proposed for the amplifier. Compared to a typical folded cascode CMOS amplifier, the proposed design has higher DC gain and slew rate as well as lower input-referred noise. This circuit has an adjustable second-order Gm-C LPF with very low power consumption. The amplifier achieves a midband gain of 70 dB and a −3dB bandwidth in the range 0.1–212 Hz. Moreover, the amplifier is designed in 0.18- $\mu \text{m}$ CMOS process and the chip area of the proposed circuit with pads is $450\times 450\,\,\mu \text{m}^{2}$ . The adjustable LPF has a 100 Hz cut-off frequency. The proposed circuit has an input-referred noise of $0.7~\mu $ Vrms, (0.1 ~ 100Hz) and a power consumption of 380 nW at 1 V supply.

Design of low power, programmable low-Gm OTAs and Gm-C filters for biomedical applications

In this paper, two programmable operational transconductance amplifiers (POTAs)—one using bulk driven attenuator (BDA) and another using programmable current mirror (PCM) are proposed in order to achieve low-Gm and high dynamic range. These OTAs are denoted as BDA-POTA and PCM-OTA respectively and are realized using composite transistors operated in the subthreshold region. The pseudo resistor is used for achieving programmability in the former and for improving the linearity and dynamic range in the latter. The proposed OTAs and two 4th order programmable Butterworth low pass filters (LPF) are designed and implemented in CMOS 180 nm technology with a supply voltage of 0.9 V. Their performances are evaluated through post-layout simulations and are found to be superior compared to those of POTAs reported in the literature for biomedical applications. The power consumption, transconductance, dynamic range and input-referred noise of BDA-POTA and PCM-OTA are [25.2 nW, (7.89–15.61 nS), (77.54–74.89 dB), (39.86–51.19 µVrms)] and [72.81 nW, (5.49–174.5 nS), (91.20–84.39 dB), (17.19–34.92 µVrms)] respectively. The power dissipation and cut off frequency range of the LPF using BDA-POTA and PCM-OTA are [197.8 nW, (30–100 Hz)] and [209.8 nW, (16–971 Hz)] respectively. The latter achieves 13.6 times wider programmability with only 5% increase in power dissipation. The proposed LPFs have better FOM compared to those reported in the literature.

Ultra-Low-Voltage Inverter-Based Operational Transconductance Amplifiers with Voltage Gain Enhancement by Improved Composite Transistors

This paper proposes topological enhancements to increase voltage gain of ultra-low-voltage (ULV) inverter-based OTAs. The two proposed improvements rely on adoption of composite transistors and forward-body-biasing. The impact of the proposed techniques on performance figures is demonstrated through simulations of two OTAs. The first OTA achieves a 39 dB voltage gain, with a power consumption of 600 pW and an active area of 447 μm2. The latter allies the forward-body-bias approach with the benefit of the independently biased composite transistors. By combining both solutions, voltage gain is raised to 51 dB, consuming less power (500 pW) at the cost of an increased area of 727 μm2. The validation has been performed through post-layout simulations with the Cadence Analog Design Environment and the TSMC 180 nm design kit, with the supply voltage ranging from 0.3 V to 0.6 V.

Novel gate-controlled bipolar composite field effect transistor with large on-state current

Novel gate-controlled bipolar composite field effect transistors (GCBFET) based on vertical MOSFETs are proposed and investigated in this paper for the first time, named VD-GCBFET and U-GCBFET, respectively, which feature the base-gate short connection mode instead of the conventional base-source short connection mode. When the devices are turned on, the composite bipolar junction transistor (BJT) provides an additional holes injection path, which is conducive to obtaining larger forward on-state current. Two conductive paths provided by the composite BJT and MOS structure not only improve the integration degree, but also greatly increase the forward on-state current while the breakdown mechanism remains unchanged. The simulation results show that, with the same structural parameters, the proposed GCBFETs have the same breakdown voltage and much lower threshold voltage compared with the corresponding vertical MOSFETs. Meanwhile, the proposed GCBFETs gain much larger forward on-state current which is over two orders of magnitude higher than that of the corresponding vertical MOSFETs. Moreover, due to the introduction of extra holes by the composite BJT, the proposed GCBFET has similar slow switching speed as IGBT.