Showing papers on "Switching time published in 1970"

Thermal switching in semiconducting glasses

Abstract: The time-dependent heat equation with a Joule heating term has been solved numerically for a material having conductivity σ = σ 0 exp ( − Δ E / kT ) for an infinite slab geometry with the electric field perpendicular to the heat flux. The results show that there is a critical field, E c below which the material remains in a low conductance state. Above this field the Joule heating term predominates the cooling term and after a field-dependent “waiting” time the temperature and current density rise rapidly at the centre of the block in a shorter “switching” time. Expressions of the switching time and critical field are given and show to be in substantial agreement with measurements on As 2 Se 2 T e and published data for chalcogenide glasses and it is proposed therefore that thermal effects play an important part in the behaviour of these meterials

Ferroelectric ceramic light gates operated in a voltage-controlled mode

Abstract: Plates of lead zirconate-lead titanate ferroelectric ceramic can have 1) low-loss optical transmission in thin, polished sections and 2) uniaxial birefringence dependent upon remanent polarization. These properties are potentially useful in electrically variable optical retarders, modulators, and latching light gates. This paper reports the results of measurements of basic light-gate devices using ferroelectric ceramic plates. A number of characteristics of the devices are reported; e.g., dependence of absolute light phase retardation on ceramic remanent polarization; dependence of ON-OFF ratio on exit aperture, switching pulse duration, and light wavelength; switching speed; and the dc hysteresis characteristic of the dependence of remanent polarization upon applied field. In the past, the use of ferroelectric devices under conditions producing partial switching has been discussed exclusively from the point of view of "charge-limited switching." This paper proposes a new mode of operating ferroelectric ceramic light gates using "voltage-controlled switching." Charge-limited switching results naturally when voltage pulses of short duration are used (appreciable ON-OFF ratios can be obtained from a light gate switched with pulses as short as 10 ns). As a result of the hysteresis in the dc switching characteristic, pulses with durations of the order of milliseconds or longer result in operation of the light gate in a voltage-controlled mode. Practical advantages resulting from this mode of operation are discussed.

Electrical and optical switching properties of single crystal bi4ti3oi2

Abstract: The full and partial switching properties of twin free Bi4Ti3O12 crystals have been studied by a combination of c-axis electrical switching measurements and optical observations of the domain patterns in the ab and ac planes. No absolute switching threshold could be detected for Bi4Ti3O12. However a sharp increase in the activation field was measured at low E. The large self reversal effects, the dependence of switching speed on 'off time and the close approach to a threshold are due to the lock-in of the reversing domain walls at energy traps. The polarization reversal occurs with a small number of domains whose sides are parallel to and extend the full length of the c-axis. Initially the domains have a lenticular ab cross-section with most of the growth occurring along the lenticle's long axis which is parallel to the crystal's b-axis. As the domains coalesce a-axis growth becomes dominant.

An experimental MM-wave high-speed path-length modulator

Abstract: High-speed binary phase-shift modulation of a millimeter wave carrier can be obtained by path-length switching. A PIN diode modulator with approximately 1.2-dB insertion loss at 56.4 GHz and 0.7 ns switching time will be described.

Computer controlled device testing and subsequent arbitrary adjustment of device characteristics

Abstract: A system for arbitrary adjustment of device characteristics to produce parameter matched arrays or to do custom design utilizes computer control. The computer is linked with electron beam scanned testing to derive individual device characteristic information such as breakdown voltage, leakage, and switching time. From such derived information the computer generates a signal back to the electron beam, increasing its current intensity to heat the device and thereby change the device''s characteristic properties. If bulk breakdown voltage is too low, for example, increased current intensity shifts the material toward n-type if done at about 500* C. in an N p diode, this would increase bulk breakdown voltage. When it reaches the predetermined (computed) level, the beam cuts off.

An adaptive resonant filter

Abstract: A solid-state adaptive (analog storage) device with stable electrical characteristics is described and demonstrated. The device is a resonant bandpass electronic filter with adaptable voltage gain; that is, the voltage gain-frequency transfer characteristic can be "set" to different values of attenuation by the application of an adapt signal and will retain that "setting" after the adapt signal has been removed. Ferroelectric materials are used as the dielectric in a filter structure composed of two capacitors bonded together so that resonant mechanical vibrations established in one (the input resonator) are coupled to the other (the output resonator). Converse and direct piezoelectric effects generate the mechanical vibrations and the output voltages, respectively. Ferroelectric effects in either capacitor provide the analog storage capabilities. The acoustical coupling mechanism employed in the device design results in electrically stable device characteristics. Previous ferroelectric adaptive devices used unstable field effect coupling mechanisms which led to unacceptable device performance. Experimental adaptive resonant filters fabricated with ceramic lead zirconate-lead titanate material compositions are discussed. These filters have electronic Q values near 100 at resonant frequencies in the range 102to 107Hz. The voltage gain-frequency characteristic has a maximum value at resonance of about 0 to +10 dB. Application of a voltage adapt pulse (100 to 300 volts) of low energy (mJ) to either side of the filter can adapt the entire gain characteristic by any value between 0 and about -60 dB within an arbitrary switching time (limited to a practical range of roughly 10+3to 10-4seconds) as determined by the pulse amplitude. Voltage gain settings are electrically stable and can be reproduced by the same or an equivalent sequence of adapting pulses.

Analog to digital converters using an integrator

Abstract: An analog-digital converter using an integrator, in which after an analog signal is integrated by the integrator during a constant time, the input of the integrator is switched to a reference voltage reverse to the polarity of the input analog signal, and the time from the switching time of the input of the integrator to the time when the output of the integrator reaches a predetermined level is measured by counting clock pulses so that the counting result corresponds to the analogue value of the input analog-signal. The clock pulses are generated by a variable frequency oscillator and the repetition frequency of the clock pulses is controlled by a compared result between the counting result of an instant period and the counting result of an immediately adjacent period until the two counting results coincide with each other, so that effect of noise of any repetition frequency superposed on the input voltage is effectively eliminated.

A Pin Diode for mm-Wave Digital Modulation

Abstract: The object of this paper is to show that a switch using PIN diodes is especially well suited for mm-wave high speed digital modulation. The PIN diodes to be described have a switching speed of less than 0.7 nsec and a power handling capability in excess of 200 mW. The quoted switching speed is realized with a transistorized driver consuming 0.8W. The switching quality factor Q of the PIN diodes is approximately 40 at 55 GHz-including the loss in the diode mount.

Switching time analysis of backward diodes

Abstract: An empirical power function for the backward diode reverse characteristic is suggested and it is used to derive the analytic closed-form expressions for the switching time of a backward diode.

Tunnel diode transient analysis with a nonlinear load

Abstract: Analytic closed-form expressions for the switching time of a tunnel diode trigger are obtained with backward diode as a nonlinear load. For given operating points the nonlinear load increases the stability and the sensitivity of the trigger, maintaining almost the same order of switching speed as for a linear load.

An adaptive ferroelectric transformer—A solid-state analog memory device

Abstract: A new solid-state adaptive (analog memory) device is described and demonstrated. The device is a flat-band electronic transformer with adaptable voltage gain; that is, the voltage gain-frequency transfer characteristic can be "set" to different values of attenuation by the application of an adapt signal and will retain that setting after the adapt signal has been removed. Ferroelectric materials are used as the dielectric in the transformer structure composed of two capacitors bonded together so that mechanical vibrations established in one (the input capacitor) are coupled to the other (the output capacitor). Converse and direct piezoelectric effects generate the mechanical vibrations and the output voltages, respectively. Ferroelectric effects in either capacitor provide the analog memory capabilities. Experimental adaptive transformers demonstrated are suitable for audio frequency operation. The voltage and current gain-frequency transfer characteristics are flat over the entire audio frequency range. Maximum gain is typically about -20 dB. Application of a voltage pulse (100 to 300 volts) of low energy (mJ) to either side of the transformer can adapt the gains to specific lower settings (between-20 and -60 dB) within an arbitrary switching time (roughly 10+3to 10-4seconds) as determined by the pulse amplitude. Gain settings are electrically stable to within a few percent of the maximum gain for periods of at least one year, and possibly indefinitely, and can be reproduced by the same or an equivalent sequence of adapting pulses.

Bistable multivibrator including special charging circuit for capacitive links for improved power to switching speed ratios

Abstract: An electronic circuit arrangement having at least one bistable multivibrator, particularly improved for use in integrated switching circuits at reduced power input for the same switching frequency or at an increased switching frequency for the same power input. The multivibrator has two switch stages, each having a switching transistor and a control transistor of the same polarity with parallel collector-emitter paths and bases connected through capacitive links to the stepping input of the multivibrator. A preliminary transistor of the same polarity has its collector-emitter section connected between the base and collector of the control transistor of a given switch stage for charging the capacitive links with a constant current during multivibrator switching. In modified embodiments, two sets of further transistors provide constant current to the preliminary transistor base and to the collectors of the switching and control transistors respectively, of the several stages. In one such embodiment, separate reference voltage sources provide base current to the two sets. In another, the same source is used for both sets. In still another, the same source is used for both sets, but indirectly as to one set. In a further modification, a plurality of multivibrators are connected in a counter chain, the reference voltage sources of which are energized by a further circuit having a plurality of constant current sources.

On the use of a backward diode in parallel with a tunnel diode in pulse shaping circuits

Abstract: The transient respose of a system having a parallel combination of a tunnel diode and a backward diode is investigated. The results show that such a system can be used for improving the top of the output pulse with some sacrifice of the switching speed.

Solid state bistable power switch

Abstract: Tin and copper provide high current and switching time capabilities for high-current resettable fuses. They show the best performance for trip current and degree of reliability, and have low coefficients of thermal expansion.

Method of improving switching speed

Abstract: The saturation characteristic of a switching transistor can be improved by using gold doping, buried layers, or clamp circuits. However, some important factors such as switching speed, loading capability, cost, and reliability may have to be sacrificed. The author describes a new technique to significantly improve not only the saturation characteristic, but also the switching speed by utilizing a two-collector-terminal transistor. The TCT structure and theory are presented. Results of experiments using the TCT and the conventional transistor are compared.

The effect of pulse rise time on nanosecond switching in magnetic thin films

Abstract: Nanosecond switching in thin magnetic films is studied by the application of easy-axis pulses with rise times from 0.4 ns to 50 ns. Switching time data with selected hard-axis bias fields and with the rise time as a parameter are presented. The switching mechanism depends on the percentage of flux switched during the ramp portion of the pulse. A comparison between the experimental data and numerical solutions based on the rotational model and the corresponding transverse signals shows that for pulses with amplitudes larger than the experimental astroid values (coherent rotation with 0.4 ns pulses) but with rates of increase S Oe/s, the stray field interaction between partially switched and unswitched regions causes appreciable flux to switch incoherently.