Unijunction Research Articles

Brief communication Modelling the static emitter characteristics of unijunction transistors

An empirical formula is presented for the static emitter characteristic of the unijunction transistor (UJT). The three parameters of the formula can be calculated easily from separate regions in the device characteristic using manual calculations.

Modeling of bistable device I-V characteristic resulting from conductivity modulation in semiconductors

The bistable I-V characteristic in a silicon diode-like device structure that resembles the double-base diode is predicted by numerical solution. This bistable characteristic results from the conductivity modulation effect coupled with an ohmic voltage drop produced by the current through a shunt resistor. The back-surface field effect has a significant influence on the minority-carrier transport of this type of bistable I-V characteristic. A two-dimensional numerical simulation is performed to explore the steady-state bistable I-V characteristic including a negative dynamic conductance region. To better understand this mechanism, a DC equivalent circuit based on a one-dimensional current-flow model is proposed. The I-V characteristic obtained by this equivalent circuit agrees well with an exact two-dimensional numerical simulation result. >

A new static memory cell based on thenegative resistance characteristic of a UJT

This paper indicates the possibility of a new static RAM cell based on the negativeresistance in the output voltage-current characteristics of a unijunction transistor (UJT). The dependence of the negative resistance characteristic on the parameters of the UJT and its impact on the performance of the RAM cell are discussed. The possibility of integrating the components of the cell into a single structure in order to reduce its overall size is also discussed.

Digital magnetic fluxmeter using unijunction transistor probe

A simple circuit has been described which measures a magnetic field using the magnetic field dependent properties of a unijunction transistor. The transistor forms part of the relaxation oscillator circuit whose frequency changes with magnetic field.

Dynamic response of a unijunction transistor in the presence of a magnetic field

The influence of a magnetic field on the small-signal dynamic response of a unijunction transistor (UJT) and the performance of a UJT sine-wave oscillator in the presence of an externally applied magnetic field are discussed. A theoretical analysis of the magnetically-induced changes in differential negative resistance and inductance (which describe the dynamic response of a UJT) is proposed for low frequencies. The change in differential negative resistance and inductance due to a magnetic field has been attributed to the corresponding change in basic electrophysical parameters (carrier mobility and carrier lifetime) of the device under investigation. This theoretical analysis has been experimentally verified. Subsequently, these results have been used in a study of magnetically-induced changes in the amplitude and frequency of a UJT sine-wave oscillator. This study suggests its possible application as a magnetic transducer.

Switching behaviour of unijunction transistor in the presence of magnetic field

The influence of magnetic field on some switching parameters (turn-on time, turn-off time and amplitude of the current pulse appearing at base 1 terminal) of a unijunction transistor has been theoretically and experimentally investigated. The various switching parameters are shown to be governed by the magneto-concentration effect.

On the inductive behaviour of the unijunction transistor in magnetic field

On the inductive behaviour of the unijunction transistor in magnetic field

THE PERIOD-ADDING PHENOMENA IN THE UNIJUNCTION TRANSISTOR SECOND ORDER CIRCUIT

This paper introduces the period-adding phenomena which occur in the unijunction transistor second order circuit. We also studied the generating process of period-adding phenomena on the phase plane and spetrum diagram.

PERIOD BIFURCATION AND CHAOTIC BEHAVIOR IN UNI-JUNCTION TRANSISTOR SECOND ORDER RLC SERIES CIRCUIT

This note deals with a new nonlinear circuit which is the forced second order unijunction transistor oscillator. It can exhibit period bifurcation and chaotic behavior when driving parameter varies in a large range.

A Novel Linear Temperature-to-Voltage/Time Converter Using Unijunction Transistor as a Sensor

A simple circuit incorporating the interbase resistance of a UJT as a sensor is described to yield linear temperature-to-voltage/time conversion over a wide dynamic range 253–410°K.

Using Unijunction Transistor as a Temperature Sensor

A novel circuit employing the interbase resistance of a medium n-doped unijunction transistor (2N 2646) as a temperature sensor has been described which yields linear temperature-to-voltage conversion over the range–20°C to 130°C with sensitivity equal to 10 mV/°C and linearity better than 1.5% up to 130°C.

Note on the Temperature Dependence of the Interbase Resistance of a Unijunction Transistor

The temperature dependence of the interbase resistance of heavily n-doped unijunction transistors (2N 2646) in the 150–410°K range is shown to obey an empirical relation of the form RT=RTo exp [B(T—To], where, RT and RTo are interbase resistance at T K and T0°K respectively, and B is a constant of the UJT channel material.

Theoretical analysis of a magneto-unijunction transistor

A theoretical explanation of the magnetic changes in electrical parameters (peak point voltage, valley point voltage and valley point current) of a unijunction transistor is proposed and compared with experimental results.

The unijunction transistor used as a high sensitivity magnetic sensor

It is shown that the unijunction transistor (UJT) may be biased so that it exhibits a critical phenomenon comparable to a second-order phase transition ( e.g., critical point of a fluid, Curie point of a magnet.). When biased at this point, the UJT behaves like a high sensitivity and high selectivity sensor for weak alternating magnetic fields, through a parametrically excited oscillation effect.

An UJT-controlled pulse microcalorimeter heating circuit

We have constructed a heating circuit based on a unijunction transistor (UJT) oscillator which delivers reproducible energy pulses of about 4.5 J to a microcalorimeter. The device was used to determine heats (enthalpies) of solution of several homologous, linear alkanes in glacial acetic acid so as to provide correction factors to convert heats of hydrogenation determined in acetic acid into heats of hydrogenation of the pure liquid alkene to the liquid alkane. This paper treats the relationship between our data and those in the literature. Because heat of solution is a function of the mole ratio of solute to solvent, it is necessary for this ratio to be the same in heat of solution studies as it was in the hydrogenation studies one wishes to correct.

Semiconductors : critical exponents of the unijunction transistor transition

The negative resistance phenomenon in the unijunction transistor is interpreted as a phase transition, for which the critical exponents β, γ' and δ are measured. Far from the critical point, these exponents have classical values : β = 1/2, γ' = 1, δ = 3. Close to the critical point, β and γ' decrease to 0.2 and 0.2 respectively.

Entrainment boundaries of relaxation oscillators coupled by low pass filters

Abstract A simple electronic network employing unijunction transistors has been used to obtain qualitative information regarding the entrainment behavior of relaxation oscillators coupled by low pass filters. Using arbitrary criteria, entrainment boundaries have been determined over the frequency range from 0.14 to 0.5 Hz for filters having time constants of 0.55,1.1 and 1.7 s. It is shown that the efficacy of entrainment is related to filter time constant and the Fourier structure of the bilaterally coupled signals

Noise measurements near an electrical transtion: Critical working conditions of the unijunction transistor

The transition from a low electrical conduction state to a high conduction state in unijunction transistors is studied. Under precise experimental conditions a “critical point” exists for the working of the device. The current fluctuations (noise) close to this critical point are measured and studied. The authors point out two experimental facts observed near the critical point: (a) the large increase of the noise level, and (b) the emergence of a 1 ƒ 2 noise (from the 1 ƒ noise observed far from the critical point). The increase of the level of noise and the change in the shape of the noise spectrum are symptomatic facts of the existence of cooperative phenomena when the device works near the critical point.

Rapid Testing for Noise Immunity of Electron Devices

Current switching in power control devices sometimes has serious noise difficulties. This paper presents a method of testing and measuring noise immunity. The noise immunity of a thyristor with magnetic core or unijunction transistor is analyzed and measured. The experiment agrees well with the theory.

A two-phase plasma-coupled static shift register

In designing an experimental 2-bit plasma-coupled shift register, fabricated with standard bipolar technology, it is shown that a simplification of the existing plasma-coupled device (PCD) concept by omission of the double base diode not only decreases the power dissipation and increases the ease of fabrication, but also increases the attractive simplicity of the basic cell. The average power dissipation of the new device is 200 /spl mu/W/bit at a clock frequency of 3 MHz. The bit density is 135 bit/mm/SUP 2/ with 10-/spl mu/m spacing between interconnection lines 10 /spl mu/m in width. A hypothetical layout with dielectric isolation and closer tolerances results in a bit density of 900 bit/mm/SUP 2/ and an estimated power dissipation of 80 /spl mu/W/bit.