Motorola Corporation

Scott L Craft

Stephen P Robb

Paul W Sanders

Henry L Pfizenmayer

Frederick C Wernett

A protective circuit for an input to a bipolar transistor (10) capable of operating in the microwave frequency range. In a first embodiment, a polysilicon diode (24) is connected across a base-emitter junction of the bipolar transistor (10). In a second embodiment, a polysilicon resistor (38) is connected in series with an emitter of the bipolar transistor (10), and the polysilicon diode (24) is connected across the series combination of the base-emitter junction and the polysilicon resistor (38). The layout of the transistor (10) and the islands of polysilicon (23, 25) housing the diode is critical since the bipolar transistor (10) is capable of operating in the microwave frequency range. In a first layout, an island of polysilicon (25) is centered between two transistor regions (47 and 48). In an exterior diode layout, a transistor region (51) is centered between two islands of polysilicon (23 and 25).

Method for forming bipolar transistor input protection

Heat removal is accomplished by utilizing a first metal conductive pad to conduct the heat from an electrical component. The first pad is juxtaposed and thereby thermally coupled by convection to one or more ground pads having plated through holes to a ground plane and heat sink.

Electronic assembly having enhanced heat dissipating capabilities

A two-stage, interstage transformer-coupled amplifier is provided with a degeneration resistor coupled between the collector of the first stage transistor and the power supply to limit the power dissipated in the first stage transistor. The first and second stages are coupled to ground through capacitor/inductor circuits to eliminate signal noise in the supply voltage. The output is filtered to remove harmonics and provide output impedance matching.

VHF power amplifier

Hybrid RF amplifiers of improved performance are obtained by arranging film resistors, metallization and other components on a circuit board so that symmetrical parts of the electrical circuit are arranged in a mirror symmetrical fashion about a line extending along the circuit board and by aligning symmetrical resistors either parallel or orthogonal to this line and by utilizing common ground metal regions to terminate resistors that are aligned and orthogonal to the mirror line and spaced apart but joined to a common ground at a single location.

Hybrid amplifier

Electrically insulating but thermally conductive 'heat shunt' components are attached to PC boards along with regular electronic components to improve heat dissipation. The heat shunts are typically a small bar of thermally conductive ceramic with spaced-apart metal mounting pads on the ends for soldering to the PC board. Their shape is similar to standard electronic components for placement by automatic machinery and they extend, for example, from a transistor collector contact pad on the PC board to an adjacent ground lead having holes plated through to the metal back plane of the PC board in contact with the heat sink.

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Phoenix, AZ, United States of America

Scott L Craft