Rca Inc.

Jitendra Goel

Herbert J Wolkstein

Arye Rosen

Subrahmanyam Yegna Narayan

Ira Drukier

Brian R Dornan

An injection laser modulator comprises a self-biased field-effect transistor (FET) and an injection laser to provide a quiescent state during which lasing of the injection laser occurs in response to a high repetition rate signal of pulse coded modulation (PCM). The modulator is d.c. coupled to an input pulse source of PCM rendering it compatible with an input pulse referenced to ground and not being subject to voltage level shifting of the input pulse. The modulator circuit in its preferred and alternate embodiments provides various arrangements for high impedance input and low impedance output matching. In addition, means are provided for adjusting the bias of the FET as well as the bias of the injection laser.

High repetition rate driver circuit for modulation of injection lasers

A positive temperature coefficient resistance element such as a sensistor and a negative coefficient resistance element such as a thermistor are arranged in a potential divider network, the output terminal of which produces a potential which is a function of temperature. The potential is applied as a bias potential to the control electrode of an amplifier circuit subject to variations in gain as a function of both control electrode voltage and temperature to reduce the gain, as a function of temperature, of the amplifier.

Temperature compensation circuit

A field effect transistor having a gate on the bottom of a groove in a body of semiconductor material with the source and drain being on a surface at opposite sides of the groove is made by first forming a recess in the surface of the semiconductor body. A metal layer is then coated on the surface of the semiconductor body and on the surfaces of the recess. A layer of a photoresist is then coated over the metal layer. The photoresist is then exposed to a beam of light whose rays extend along a path which is at a very small angle with respect to the surface of the semiconductor body to fully expose a narrow portion of the photoresist layer at one edge of the recess. The fully exposed portion of the photoresist layer is removed to expose a narrow area of the metal layer along the edge of the recess. The exposed portion of the metal layer is then removed and a groove is formed in the portion of the surface of the semiconductor material exposed by removing a portion of the material layer. A metal film is coated on the bottom of the groove to form the gate of the field effect transistor with the metal layer on the bottom of the recess at one side of the groove and the metal layer on the surface of the semiconductor body at the other side of the groove forming the source and drain of the field effect transistor.

Method of making a field effect transistor

A field effect transistor is mounted in a flip-chip carrier which is in contact with one surface of a metal plate, the other surface of the plate being in contact with one surface of a block of beryllium oxide. A metal sheet, connected to a ground plane, is in contact with the one surface of the block and the surface of the block opposed therefrom. The plate and the sheet have a space therebetween. A film resistor is disposed upon the block in the space.

Self biasing of a field effect transistor mounted in a flip-chip carrier

A microwave power limiter for generating an output RF signal of substantially constant power level in response to an input RF signal of varying power level comprises a dual gate field effect transistor (FET). The FET is biased such that the RF power output variation is small compared to the input power variation in the saturation region. A number of FET cascaded stages may be utilized to reduce this power output variation. A small signal amplifier including a number of FET cascaded stages may be employed in the limiter to increase the power level to that gain or drive level compatible with the saturated FET stages.

Microwave power limiter comprising a dual-gate FET

A short gate field effect transistor having a gate on the bottom of a recess in a body of semiconductor material with the source and drain being on the surface of the semiconductor body at opposite sides of the recess is made by providing a metal film on the surface of the semiconductor body with the metal film having an opening therein. A recess is formed in the portion of the semiconductor body in the opening in the metal film. While protecting the bottom portion of the recess, metal films are plated up on each side of the recess until the spacing between the metal films across the recess is equal to the desired length of the gate. The gate is then deposited on the bottom of the recess using the plated metal films as a mask to control the length of the gate.

Method of making a short gate field effect transistor

A mask for manufacturing microcircuits is comprised of a substratum and a layer of matter, such as, for example gold, adjacent the substratum. An aperture is located in the layer of matter. The aperture in the layer of matter exhibits a cross-section resembling an inverted isosceles trapezoid. The method for manufacture of the mask comprises the steps of appositioning a patterned layer of photoresist to a layer of gold which is adjacent the substratum. The structure comprising the photoresist, the gold layer and the substratum is exposed to a beam of ions having a preselected kinetic energy such that the ions remove gold exposed by apertures in the photoresist layer. The kinetic energy of the ions is selected such that an aperture is eroded in the layer of gold, the aperture exhibiting an inverted isosceles trapezoidal cross-section.

Growing community of inventors

Kendall Park, NJ, United States of America

Jitendra Goel