Bias Resistance Research Articles

Cooled P-InAsSbP/n-InAs/N-InAsSbP double heterostructure photodiodes

Double heterostructure (DH) photodiodes (PDs) with InAs active layer and back-side illumination have been studied in the 100–300K temperature range. Temperature dependence of a spectral response was standard for InAs based PDs while saturation current (or zero bias resistance) was characterized by a single value of the activation energy with domination of a diffusion current at most temperatures. As a result the simulated detectivity value was beyond the known numbers for homo- and heterojunction InAs PDs.

The Solving of Bias Resistor and Its Effect on the RS485 Fieldbus

 Abstract—The RS485 fieldbus has been widely used in communication, data collecting and related fields. The stable communication is the premise of its application. Maximum load, terminal resistor and bias resistor are three main parameters of RS485 field bus, which directly influence the stable of system. This paper adopts the current flow method to solve the theoretical value of bias resistor based on the equivalent circuit model of RS485 field bus, and further analyzes the influence on the maximum load and terminal resistor. The research result offers a theoretical basis for the application of RS485 filed bus and is very useful in many applications. 

A Switchable Microwave Reflector Using Pin Diodes

A switchable microwave reflector, reflection of which is actively controlled using diodes was proposed. Pin diodes have large resistance and capacitance without DC bias and small resistance and inductance with DC bias in microwave band. The reflector was designed by using the characteristics. In this paper, effects of a periodic structure on the reflector were verified with simulation and equivalent circuit model. A prototype reflector was able to switch between about -20 dB and -0.1 dB reflection coefficient at 2 GHz.

POSFET touch sensing transducers: Interface electronics design methodology based on the transconductance-to-drain-current efficiency gm/ID

This paper deals with tactile sensing systems based on a piezoelectric polymer poly(vinylidene fluoride-trifluoroethylene) film on the gate area of a MOS (Metal Oxide Semiconductor) transistor: Piezoelectric Oxide Semiconductor Field Effect Transistor, POSFET. More specifically, we present the design and analysis of the interface electronic circuit between the touch sensor transducer and the signal conditioning circuit stage. The circuit configuration is based on a NMOS transistor in common-drain and floating gate bias configuration. Such configuration enhances and complements the transducer's response. However, the circuit interface design suffers of the very difficult analytical tractability. For this reason, a graphical methodology, intended to give a criterion for achieving the selection of the most appropriate bias resistance value has been developed. The methodology utilizes the Advanced Compact MOSFET (ACM) model and the gm characteristic as function of the NMOS transistor drain current ID.A design space map shows confidence regions where the specifications such as touch sensing device gain, current consumption and source resistance value are met. The design methodology enables to push the performance of the POSFET by selecting the most appropriate bias resistance value and it reduces time-consuming iterations which are normally required. As a proof of concept of the proposed methodology, measurements as well as a design example are presented.

Self-Adjusting Bias-Resistor Unit for a Semiconductor Detector

A self-adjusting resistor unit is described that stabilizes the bias voltage of a semiconductor detector, while always keeping the parallel thermal noise of the bias resistor significantly below the detector shot noise. The user is exempted from adjusting the bias resistor to the detector leakage current for achieving optimum operating conditions. Moreover, the unit avoids the drop of the operation voltage on the detector when the reverse current increases up to several orders of magnitude without any further intervention. The self-adjusting unit can lead to a significant extension of the time of operation of the detector under stable conditions.

Resistive damping implementation as a method to improve controllability in stiff ohmic RF-MEMS switches

This paper presents in detail the entire procedure of calculating the bias resistance of an ohmic RF-MEMS switch, controlled under resistive damping (charge drive technique). In case of a very stiff device, like the North Eastern University switch, the actuation control under resistive damping is the only way to achieve controllability. Due to the short switching time as well as the high actuation voltage, it is not practical to apply a tailored control pulse (voltage drive control technique). Implementing a bias resistor of 33 MΩ in series with the voltage source, the impact velocity of the cantilever has been reduced 80 % (13.2 from 65.9 cm/s), eliminating bouncing and high initial impact force during the pull-down phase. However, this results in an affordable cost of switching time increase from 2.38 to 4.34 μs. During the release phase the amplitude of bouncing has also been reduced 34 % (174 from 255 nm), providing significant improvement in both switching operation phases of the switch.

High linearity current communicating passive mixer employing a simple resistor bias

A high linearity current communicating passive mixer including the mixing cell and transimpedance amplifier (TIA) is introduced. It employs the resistor in the TIA to reduce the source voltage and the gate voltage of the mixing cell. The optimum linearity and the maximum symmetric switching operation are obtained at the same time. The mixer is implemented in a 0.25 μm CMOS process. The test shows that it achieves an input third-order intercept point of 13.32 dBm, conversion gain of 5.52 dB, and a single sideband noise figure of 20 dB.

Optical Triggering of 12 kV 1 cm<sup>2</sup> 4H-SiC Thyristors

We report on switch-on of 12 kV, 1cm2 optically triggered 4H-SiC thyristor fabricated by CREE Inc., to Imax=270 А with current rise time of ~ 3 s. Temperature dependence of holding current Ih in this thyristor has been experimentally studied in the temperature range from 300 to 425 K. It is shown that measurements of Ih temperature dependence under condition of optical switch-on at small anode bias and large load resistance reveal the existence of a ”weak point” within the optical window. This point is characterized by a much smaller critical charge than that within the remaining part of the window.

Performance of gas source MBE grown InAlGaAs photovoltaic detectors tailored to 1.4 μm

InAlGaAs photodiodes with 50% cut-off wavelength of 1.41μm at room temperature have been grown by using gas source MBE with convenient and reliable procedure, and the performances have been characterized in detail. The InAlGaAs absorption layer shows a mismatch of −8×10−5 to the InP substrate with a full width at half maximum of around 20arcs. Dark current of 247pA at reverse bias of 10mV and zero bias resistance of 41MΩ has been measured for the devices at room temperature with 200μm mesa diameter. The dark current of this InAlGaAs photodetector is about 20 times lower than the In0.53Ga0.47As photodetector with similar structure processed at the same time.

A New Circuit Model of Small-Signal Amplifier Using MOSFETs in Triple Darlington Topology

A small-signal amplifier with three identical MOSFETs in Darlington's topology is proposed and qualitatively analyzed perhaps for the first time. Unlike CS- MOSFET amplifiers, the voltage gain of the proposed circuit is found considerably higher than unity. This amplifier can be used to amplify audio range signal excursions swinging in 0.1- 2mV range. In the narrow-band performance range, the proposed amplifier produces simultaneously high voltage and current gains with low harmonic distortion. These properties offer a flexible application range to the proposed circuit as high-voltage-narrow-band amplifier in permissible audio- frequency range. An additional biasing resistance RA is to be essentially used in the proposed circuit to maintain its voltage/current amplification property. Variations in voltage gain as a function of frequency and different biasing resistances, temperature dependency of performance parameters like voltage gain, bandwidth, current gain, input/output noises and total harmonic distortion of the amplifier are perused to provide a wide spectrum to the qualitative studies.

Energy Harvesting Tests With Galfenol at Variable Magneto-Mechanical Conditions

This paper deals with the experimental characterization of Galfenol (iron-gallium alloy) and its energy harvesting capabilities. Two rods are considered, one with a stress annealing treatment. The impact on the harvesting performance of magnetic bias, mechanical prestress and termination resistor are considered. Moreover, the performed measurements allow to verify an important feature of the energy conversion of this magneto-mechanical material: the energy harvested loops, in the B-H plane, are confined within the magnetic characteristics at the extrema of the applied stress. This suggests the significance of the static characteristics in the energy conversion process.

Accurate analysis of conduction and resistive-switching mechanisms in double-layered resistive-switching memory devices

Resistive-switching and current conduction mechanisms have been studied in TiN/Ti/TiOx/HfOx/TiN resistive-switching random access memories (RRAMs). From I-V characteristics and temperature measurement, thermionic emission is found to be the most appropriate mechanism representing the dominant current conduction in all the bias regions and resistance states. Low-frequency noise power spectrum is measured to analyze accurately the conduction mechanism, which corroborates the thermionic-emission. Also, using the migration of oxygen ions depending on the polarity of the applied field, we propose the resistive-switching model of a double-layered RRAM to explain the unique resistive-switching characteristics.

Flexible PVDF-TrFE pyroelectric sensor driven by polysilicon thin film transistor fabricated on ultra-thin polyimide substrate

In this work we present a flexible pyroelectric sensor composed by a PVDF-TrFE capacitor realized on ultra-thin polyimide film (5μm thick), integrated with a n-channel low temperature polysilicon thin film transistor also fabricated on ultra-thin polyimide (8μm thick). Exploiting a multi-foil approach, the pyroelectric capacitors and the transistors were attached one over the other reaching a final thickness of about 15μm. The bottom contact of the sensor capacitance was connected to the gate of the transistor by a silver ink, while, for bias and load resistances, we used external elements. The active sensor area was defined by a circular capacitor with a diameter of about 2mm. In order to enhance PVDF-TrFE pyroelectric properties, an external stepwise voltage was applied to the structure up to values of 160V at a temperature of about 80°C. The devices were then tested, at different working frequencies (up to 800Hz) under a specific infrared radiation provided by a He–Ne laser, with a wavelength of 632nm and maximum power of 5mW. An output signal of tens of millivolt was observed at 10Hz, exploiting the pre-amplification of polysilicon thin film transistor.

Punch-through protection of SSDs

The effectiveness of punch-through protection (PTP) structures on n-on-p AC-coupled silicon strip detectors using pulses from a 1064nm IR laser, which mimics beam accidents, is investigated. The voltages on the strip implants are measured as a function of the bias voltage and incoming particle flux. We present a 4-resistor model to describe the sensor after large particle fluxes, which is then used to characterize the effectiveness of PTP structures. The effectiveness of PTP structures is presented in terms of total strip implant to bias rail length, type of surface treatment used for strip isolation, coverage of the polysilicon bias resistor, and radiation damage from protons, neutrons and pions.

18-GHz, 4.0-aJ/bit Operation of Ultra-Low-Energy Rapid Single-Flux-Quantum Shift Registers

We demonstrate rapid single-flux-quantum (RSFQ) circuits with reduced energy consumption by lowering the driving voltages and critical currents of Josephson junctions (JJs). At lowered voltages, the energy statically consumed by bias resistors (which is dominant in RSFQ circuits) is reduced. In addition, we show that when RSFQ circuits are driven by lowered constant voltages, the dynamic energy consumption resulting from the switching of JJs is reduced because of the suppression of the amplitudes of the signal voltage pulses, even though the switching speed becomes slower. Utilization of miniaturized JJs with smaller critical currents also leads to the reduction of static and dynamic energy consumption without decreasing the switching speed. We have designed and tested ultra-low-energy 8-bit shift registers, and verified the correctness of high-speed operations up to 18 GHz. The average energy consumption, including that at the bias resistors, was measured at 4.0 aJ/bit, which represents an energy efficiency two orders of magnitude better than that of standard RSFQ circuits.

18-GHz, 4.0-aJ/bit Operation of Ultra-Low-Energy Rapid Single-Flux-Quantum Shift Registers

We demonstrate rapid single-flux-quantum (RSFQ) circuits with reduced energy consumption by lowering the driving voltages and critical currents of Josephson junctions (JJs). At lowered voltages, the energy statically consumed by bias resistors (which is dominant in RSFQ circuits) is reduced. In addition, we show that when RSFQ circuits are driven by lowered constant voltages, the dynamic energy consumption resulting from the switching of JJs is reduced because of the suppression of the amplitudes of the signal voltage pulses, even though the switching speed becomes slower. Utilization of miniaturized JJs with smaller critical currents also leads to the reduction of static and dynamic energy consumption without decreasing the switching speed. We have designed and tested ultra-low-energy 8-bit shift registers, and verified the correctness of high-speed operations up to 18 GHz. The average energy consumption, including that at the bias resistors, was measured at 4.0 aJ/bit, which represents an energy efficiency two orders of magnitude better than that of standard RSFQ circuits.

Analysis of current voltage characteristics of MWIR homojunction photodiodes for uncooled operation

Dark currents n+/ν/p+ Hg0.69Cd0.31Te mid wave infrared photodiodes were measured at room temperature. The diodes exhibited negative differential resistance at room-temperature, but with increasing leakage currents as a function of reverse bias. The current–voltage characteristics were simulated and fitted by incorporating trap assisted tunneling via traps and Shockley–Read–Hall generation recombination process due to dislocations in the carrier transport equations. The thermal suppression of carriers was simulated by taking energy level of trap (Et), trap density (Nt) and the doping concentrations of n+ and ν regions as fitting parameters. Values of Et and Nt were 0.78Eg and ∼6–9×1014cm−3 respectively for most of the diodes. Variable temperature current voltage measurements on variable area diode array (VADA) structures confirmed the fact that variation in zero bias resistance area product (R0A) is related to g–r processes originating from variation in concentration and kind of defects that intersect a junction area.

INFRARED SENSOR ON THE BASIS OF LEAD-TIN CHALCOGENIDE MULTICOMPONENT SOLID SOLUTIONS

The linear photovoltaic infrared sensor arrays have been formed on the basis of -layer//(KCl, )/Al(Pb) and Pb/ -layer/ barrier-surface structures, which were obtained by the liquid phase epitaxy and thermal vacuum deposition techniques. At the80 170170 K, peak wavelength 8 12,2 and cutoff wavelength 8,3 12,8 they had the zero bias resistance area product = 0,18 2,72 , peak quantum efficiency =0,28 0,52 and peak detectivity (0,61 4,51) 1010 cm·

Amplifier Bias Stability Design on Output Range Temp. Coefficient

The limitations of empiric design methods for amplifier biasing stability were pointed out. Critical bias and output range of voltage divider biasing amplifier were discussed. The relationship between bias temperature coefficient and β temperature coefficient was discussed as well. The ratio of bias temperature coefficient to β temperature coefficient is defined as effecting factor. Amplifier bias stability is designed based on output range temperature coefficient. The methods for designing base biasing resistance of voltage divider biasing amplifier on the basis of output range temperature coefficient and for analyzing biasing stability of this amplifier are introduced.

Estimation of Nb Junction Temperature Raised Due to Thermal Heat from Bias Resistor

Superconducting integrated circuits should be operated at low temperature below a half of their critical temperatures. Thermal heat from a bias resistor could rise the temperature in Josephson junctions, and would reduce their critical currents. In this study, we estimate the temperature in a Josephson junction heated by a bias resistor at the bath temperature of 4.2K, and introduce a parameter β that connects the thermal heat from a bias resistor and the temperature elevation of a Josephson junction. By using β, the temperature in the Josephson junction can be estimated as functions of the current through the resistor.