GaAs m.a.o.s.f.e.t. memory transistor

A new non-volatile memory device is reported. This device is a GaAs m.o.s.f.e.t. with charge storage in the gate in which is a double oxide structure of aluminium oxide and GaAs native oxide, both oxides are grown anodically. The fabrication of the device is described and the results of initial measurements on the charging and charge retention properties are presented.     

Current-kink noise of n-channel enhancement e.s.f.i.-m.o.s. s.o.s. transistors

An experimental study of the low-frequency-noise properties of n-channel epitaxial silicon films on insulator m.o.s. s.o.s. transistors has been performed. The measurements show an excessive noise contribution at drain voltages corresponding to the current-kink effect for temperatures ranging from 4.2 to 300 K.     

Noise behaviour of the m.o.s.f.e.t. at v.h.f. and u.h.f.

The optimum noise figures of an m.o.s.f.e.t. at u.h.f. and at pinch-off are calculated using a simplified equivalent circuit. The noise parameters are also determined experimentally. Theory and experiment are shown to be in good agreement. Noise parameters of the m.o.s.f.e.t. for the frequency range 0.1?0.8 GHz are given.     

Switching in m.i.s.m. and m.i.s.i.m. structures

Switching has been observed in metal?thin-insulator?n-p+ structures, where the thin insulator is SiO2, or polycrystalline silicon. In this letter two alternative structures are discussed in which the n-p+ junction is replaced by a Schottky barrier. In the second device proposed two thin-insulator structures back-to-back are shown to exhibit bidirectional switching.     

V.H.F. and u.h.f. Gunn-effect oscillators

In this letter, the use of the Gunn device as a broadband negative resistance, somewhat analogous to a tunnel diode, is explored. v.h.f. and u.h.f. oscillators are described; the frequency is determined by an external resonant circuit and is very nearly independent of the parameters of the Gunn-effect sample.     

U.H.F. low-noise GaAs m.e.s.f.e.t. amplifier for colour t.v. broadcasting translator

Low-noise amplifiers for u.h.f. colour t.v. broadcasting translator use have been successfully developed by using 1 ?m gate GaAs m.e.s.f.e.t.s. The obtained performances revealed that a GaAs m.e.s.f.e.t. has low-noise and low intermodulation distortion characteristics, even in the 500?800 MHz frequency range, compared with a Si bipolar transistor.     

Subthreshold behaviour of e.s.f.i.-s.o.s. transistors

Theoretical and experimental results are presented which illustrate the influence of various parameters on the subthreshold behaviour of e.s.f.i.-s.o.s. transistors. The numerical analysis accounts for the thin silicon film and the existence of a second interface. A comparison is made with a corresponding bulk transistor, furthermore, between a two- and a one-dimensional analysis of e.s.f.i.-s.o.s. m.o.s.t. The agreement for real cases is found to be excellent.     

V.P.E. GaAs m.e.s.f.e.t. structure using oxygen injection during buffer layer growth

GaAs m.e.s.f.e.t. structures with high-resistivity buffer layers were prepared by introducing oxygen into the deposition system during growth. The electrical properties of the buffer layers are independent of the oxygen content of the gas phase over a large range of partial pressures. The characteristics of devices prepared with such layers are excellent.     

Integrated n.m.o.s. operational amplifier for c.c.d. transversal filters

An integrated operational amplifier employing a new high-gain input stage and implemented with n.m.o.s. enhancement devices is reported. The circuit has been designed with reference to the output differential-charge amplifier of a c.c.d. transversal filter. The performance parameters of the amplifier are presented.     

I.C.-compatible completely planar GaAs m.e.s.f.e.t.s. by selective diffusion

Completely planar GaAs m.e.s.f.e.t.s were produced by selective open tube diffusion from tin-doped spin-on SiO2 films. After the diffusion process no change in the surface morphology was observed in the doped regions. The evaluation of saturation currents of the m.e.s.f.e.t.s show very good homogeneity. Isolation between doped areas was excellent. Sample preparation and device results are presented; possible applications are outlined.     

E.I.R.P. allocation in single-destination f.d.m.a. satellite communication systems

The optimum allocation of downlink e.i.r.p. in a satellite communication system utilising single-destination f.d.m.a. carriers and a downlink multiple-beam antenna (m.b.a.) is considered. The optimum gain setting for the m.b.a. is determined and it is shown that this setting is independent of the level of the intermodulation and front-end noise generated by the satellite. The optimum allocation is expressed in terms of simple formulae which can be used for adaptive as well as static allocation of satellite power and antenna gain.     

Avalanche noise in GaAs m.e.s.f.e.t.s

Instabilities in the d.c. characteristics of GaAs m.e.s.f.e.t.s for drain to source voltages greater than 4 V. believed to be due to reloading of traps in the interface between active layer and bulk material, or gunn-domain formation, seem to have their origin in avalanche breakdown of the back diode under the drain contact. Microplasma switching, vertical to the active layer, strongly modulates the drain current producing large broadband noise power.     

New V-groove double-diffused m.o.s. (v.d.m.o.s.)

A new V-groove double-diffused m.o.s. (v.d.m.o s.) is proposed which combines the V-groove technology and the double-diffused m.o.s. (d.m.o.s.) technology. The fabrication processes arc qualitatively described. The gate is located on the vertical V-shaped surface, and the effective channel length is controlled by the vertical-diffusion process of the double-diffusion step. The v.d.m.o.s. is expected to have a faster speed and higher production yield than the ordinary d.m.o.s.     

Conversion gain of m.e.s.f.e.t. drain mixers

A theoretical analysis of the gain properties of m.e.s.f.e.t. drain mixers is presented. The m.e.s.f.e.t. model includes the nonlinearity of both the transconductance and the drain resistance. For a special case, a simple analytical expression for the gain is given. Numerical results for a typical example are briefly presented as an illustration.     

Octave-band GaAs f.e.t. y.i.g.-tuned oscillators

The design of a y.i.g.-tuned f.e.t. oscillator that covers the X-band octave of 6 to 12 GHz is presented. The oscillator uses a compound feedback scheme to generate a negative conductance over the required bandwidth. Excellent agreement is obtained between the computer predictions and the experimental results.     

n-channel inversion-mode InP m.i.s.f.e.t.

Capacitance/voltage and m.i.s.f.e.t. inversion-mode f.e.t. data are reported for p-type InP. It is shown that the surface of this material appears to be inverted at zero gate bias and that good inversion-mode (normally-off) device behaviour is possible.     

M.O.S.T. channel-length measurement

A simple and accurate method of determining the channel length of m.o.s. transistors after manufacture is presented. The technique relies on various 3-terminal capacitance measurements, from which the gate-channel capacitance and hence channel length may be obtained.     

Performance of GaAs power m.e.s.f.e.t.s

Power performance results at 4 GHz are summarised for GaAs m.e.s.f.e.t.s ranging in size from 4 to 16 mm gate periphery. A double-chip 16 mm unit operated at 24 V source-drain bias produced 13.5 W with 3 dB gain and 10.7 W with 8.1 dB gain. Although lack of perfect power and gain scaling is observed, the degradation in output power of the 16 mm devices was only 1 dB compared to the smaller devices.     

More active RC filters using the d.v.c.c.s./d.v.c.v.s.

Novel configurations using a differential-voltage-controlled current source, differential-voltage-controlled voltage source (d.v.c.c.s./d.v.c.v.s.) as the active building block are described. The configurations assume that the active building block is divided into two independent parts initially.     

Analogue c.c.d. correlator using monolithic m.o.s.t. multipliers

A 32-stage analogue correlator has been hybridised by using a multitapped c.c.d. delay line and m.o.s.t. multipliers fabricated on the same silicon chip. A multiple-port sample?hold system has been adopted for storage of the reference signal, thereby allowing it to be refreshed continuously. The viability of a design for a fully analogue monolithic c.c.d. correlator is established.