Showing papers by "Motorola published in 1968"

Relay circuits employing a triac to prevent arcing

Abstract: Disclosed is circuitry for controlling the flow of current from an AC source to a load and includes a bilateral semiconductor switch such as a semiconductor triac connected in parallel with the contacts of an electromechanical relay. The relay and triac are connected in series with the AC source and the load. Circuit means are connected between a gate electrode of the triac and circuit input terminals to which the AC source is connected and provides turn-on gate current for the triac prior to and during the closure of the electromechanical relay contacts to prevent effects of contact bounce. This circuit means also provides a sustaining or hold current to the triac subsequent to the opening of the relay contacts and thereby prevents contact arcing. The triac conducts before the relay contacts close and after the relay contacts open.

A high-performance monolithic IF amplifier incorporating electronic gain control

Abstract: A direct-coupled monolithic IF amplifier that incorporates an active gain control stage and exhibits a power gain of 50 dB and an AGC range of 60 dB at 50 MHz is described. This circuit has negligible change in either input or output admittance, and has excellent signal linearity over the full range of gain control. Experimental and theoretical analyses are made of the large signal response, stability, available gain, and noise behavior of the circuit. An application to color television is discussed in which the functions of the 45-MHz IF amplifier and the dc-AGC circuitry are fabricated on a single die.

Electronically tuned antenna system

Abstract: 1,199,136. Aerial coupling arrangements. MOTOROLA Inc. 19 March, 1969 [16 April 1968], No. 14460/69. Heading H4A. A receiving aerial 10, Fig. 1, such as a rodtype motor-car aerial, is remote from associated signal processing stages and has a tank circuit located at its base which includes a voltage variable tuning reactance 26. As described, the tank circuit is contained in a housing 12 and comprises a transformer 18 with a primary winding 20 and a secondary winding 22. The voltage variable reactance 26 is a two-terminal PN junction semi-conductor capacitor device, and it is connected with a blocking capacitor 24 across the winding 22. Signals from the aerial 10 are coupled to the signal processing stages by a coaxial cable 28, which also connects variable biasing voltage from a tuning potentiometer 50 to the element 26 via resistors 52, 54. Output from the potentiometer 50 is also used to tune a heterodyning oscillator 32. In another embodiment (Fig. 3, not shown) a transistor-type R.F. amplifier is located with the tank circuit at the base of the aerial. Three leads are provided to the signal processing stages, one for output from the R.F. amplifier, one for A.G.C. of the R.F. amplifier, and one for bias voltage for the voltage variable capacitor in the aerial tank circuit.

Capacitor discharge ignition system

Abstract: A capacitor discharge ignition system is provided with a control arrangement to prevent operation of an engine at excessive speeds. For example, when the engine exceeds a predetermined speed of operation, the control arrangement is effective to terminate the generation of the ignition firing pulses to the spark plug of the engine. The control arrangement includes a capacitor connected at one end to the cathode of an SCR switching device that controls the discharge of a charging capacitor into an ignition coil. The other end of the capacitor is connected in the triggering circuit of the SCR. The capacitor discharge ignition system is arranged to charge the charging capacitor during a first half cycle of operation of one polarity and subsequently to discharge the capacitor into the ignition coil by triggering the SCR during the following half cycle of operation of opposite polarity. The charging of the capacitor and the triggering of the SCR are controlled by voltage and current waveforms generated by a control winding that is disposed on a ferromagnetic core. The ferromagnetic core is positioned adjacent the rotating magnetic field that is developed for example by a permanent magnet carried by the flywheel of the engine.

Remote control system for operation over same audiochannel providing voice signals between remote station and base station

Abstract: Remote control system for controlling radio at base station from remote point over single audio channel which provides voice signals between remote and base stations, and which does not require DC continuity and operates within a fixed maximum frequency. A short burst of high amplitude guard tone is applied over the channel from the remote station to the base station to actuate a control at the base station which renders the controls thereat operative and blocks transmission of audiosignals from the base station to the channel. The remote station then applies lower amplitude tones to the audiochannel to actuate controls at the base station, with guard tone being applied continuously at low level during application of audio signals from the remote station to the base station. The base station responds to termination of tone signals (or to disconnect tones) to provide disconnect action, reset the controls and permit the base station to apply signals to the audio channel.

Synchronous supervisory unit for mobile telephone system

Abstract: A synchronous supervisory unit for mobile telephone operation is capable of assuming any one of a plurality of states depending upon the operations to be carried out by the supervisory system. A shift from one state to another occurs when certain predetermined conditions exist. A single oscillator provides a plurality of timing pulses to synchronize the operation of the system. A separate oscillator develops a plurality of tone signals for use in the telephone system.

Antenna for miniature radio receiver including portions of receiver housing and chassis

Abstract: Antenna for radio receiver of the capacitively loaded vertical ground plane type wherein an active vertical portion is formed by parts of the receiver and is connected to a conductive escutcheon to form a capacitive loading structure for the vertical antenna. The lower end of the vertical antenna is connected to shield cans and grounded conductors on the chassis which form an effective ground plane. The signal from the top of the vertical antenna is coupled through a matching circuit to the base of a transistor. A jack for connecting an external antenna is connected between the ground plane and a point on the vertical antenna.

Automatic gain control rf-if amplifier

Abstract: Disclosed is a differential amplifier circuit featuring electronic gain control, and this circuit may be constructed in monolithic integrated form. In one embodiment of the invention, first and second pairs of differentially coupled transistors are connected respectively to first and second differentially coupled input transistors, and the input transistors are connectable to a source of differential input signals. Differential output signals are derived at the outputs of transistors in each of the pairs of transistors, and by applying an automatic gain control (AGC) signal at a node which is common to the transistor pairs, electronic gain control is obtained without a differential signal arising therefrom. In another embodiment of the invention, an output differential amplifier stage is directly coupled to transistors in the first and second pairs of transistors so that any common mode signal present there is rejected in said output stage.

Mushroom epitaxial growth in tier-type shaped holes

Abstract: A STRUCTURE FORMED BY, AND A PROCESS FOR GROWING EPITAXIAL LAYERS OF SILICON ON AN EXPOSED SURFACE OF A SILICON WAFER THROUGH OPENINGS IN A PASSIVATING STRUCTURE HAVING A PREDETERMINED "TIER-TYPE" CONFIGURATION. THE DEVICES FORMED BY THIS METHOD HAVE IMPROVED BREAKDOWN VOLTAGE CHARACTERISTICS. FURTHER, THE METHOD MAKES POSSIBLE THE ABILITY TO VARY AND CONTROL JUNCTION CAPACITANCE AS REQUIRED.

High voltage schottky barrier diode

Abstract: 1,229,776. Semi-conductor devices. MOTOROLA Inc. 12 Aug., 1969 [21 Aug., 1968], No. 40265/69. Heading H1K. A surface barrier diode is provided on one surface with an annular region 16 forming a PN junction with the surrounding region 12 to increase the breakdown voltage of the device, a further annular region 18 being situated within the region 16 and forming a further PN junction therewith. The surface barrier electrode 19 is provided in contact with all three regions 12, 16, 18, its periphery lying within the region 18. In the embodiment a Si n type epitaxial layer 12 is provided on an n + type substrate 11, and annular p type and n type regions 16, 18 are formed by diffusion of B and P respectively through an oxide mask 13. The electrode 19 of Mo is then deposited and covered with a layer 20 of Au. The thickness of the region 16 left between the regions 12 and 18 may be made as small as possible consistent with avoidance of punch-through. An additional band of metallization may contact the region 12 through the oxide layer 13 around the electrode 19.

Photodiode preamplifier circuit for a card reader system

Abstract: A photodiode preamplifier circuit including input terminals to which a photodiode may be connected. The photodiode senses the presence of a mark or a hole on a sense card and in turn provides a change in voltage at a control transistor to which the photodiode is connected. An output transistor is connected to the control transistor and is conductively controlled by the signal applied to the control transistor to in turn provide an output signal at one or the other of two binary levels. A reference level control means is connected between the control transistor and the input terminals of the amplifier and responds to current variations in the control transistor to produce a compensating current to the photodiode. This compensating current maintains a constant DC voltage level with reference to a constant threshold level at the output transistor.

Avalanche drift instability in planar passivated p-n junctions

Abstract: Some factors which affect the breakdown voltage of planar passivated p-n junctions and which influence breakdown drift instability are discussed. Experiments describing these phenomena are reported. An activation energy for walk-out recovery is given as approximately 0.35 eV. It is argued that charge motion parallel to and probably within the oxide-semiconductor interface is occurring. Experiments performed to verify this parallel charge drift are related which confirm the effect. Finally, evidence for a mobile negative species is given.

Overload compensation circuit for antenna tuning system

Abstract: A radio receiver is supplied with signals from a high impedance capacitive antenna coupled in series with a low impedance resistive load in the form of the emitter-base circuit of a common-base RF transistor amplifier through a series-tuned circuit, including a varactor diode connected in series with an inductor. A source of DC biasing potential is provided to vary the biasing voltage on the diode in order to change its capacitance to tune the circuit over a predetermined band of frequencies. Overload compensation for the varactor diode is provided by utilizing the automatic gain control (AGC) voltage of the receiver, with the AGC voltage being applied to the base of the RF amplifier transistor to vary the biasing potential thereon. This in turn causes a corresponding variation in the impedance of the emitter-base path of the transistor with an increasing impedance being caused by increased signal levels. As a result, increasing amounts of the signal supplied by the antenna are dropped across the emitter-base path of the transistor at high signal levels, thereby limiting the RF signal level across the varactor diode to prevent rectification of high level signals thereby.

Electrolytic etching of platinum for metallization

Abstract: A PLATINUM THIN FILM IS PATTERENED BY A SELECTIVE ETCHING PROCESS, INCLUDING THE STEP OF DEPOSITING THE PLATINUM FILM ON A CONDUCTIVE SUBSTRATE, FOLLOWED BY THE APPLICATION OF A PHOTORESIST FILM ON THE PLATINUM FILM, PATTERENED IN THE SAME IMAGE AS DESIRED IN THE PLATINUM. THE COMPOSITE STRUCTURE IS THEN SUBJECTED TO ALTERNATION CURRENT ELECTROLYSIS IN A BATH COMPRISING AN ELECTROLYTE WHICH FORMS A SOLUBLE COMPLEX WITH THE PLATINUM. THE TECHNIQUE IS SPECIFICALLY APPLIED TO THE FACRICATION OF SEMICONDUCTOR DEVICES WITH TITANIUM-PLATINUM METALLIZATION.

Adaptive radar clutter rejection

Abstract: A control loop in a radar receiver is jointly responsive to range gated video and a reference potential to establish a filter control signal. A plurality of range gated filters are responsive to the filter control signal to adjust the frequency response in a manner such that clutter is rejected yet the maximum frequency bandwidth is dynamically provided for moving target detection for varying clutter conditions. Each range gated filter has a filter element which is switchable such that the effective electrical properties of the element vary in accordance with the switching to thereby effect a change in the frequency characteristics of the filter. The switching rate is much higher than the pulse repetitive frequency of the radar such that the switching rate does not interfere with signals being processed through the filter. In one embodiment, a variable duty cycle pulse generator having a fixed frequency is utilized to effect control over the frequency characteristics of a filter.

Selection and interconnection of devices of a multidevice wafer

Abstract: A MEHTOD OF TESTING AND SELECTING SEMICONDUCTOR DEVICES ON A MULTIDEVICE WAFER WHEREBY THE DEVICES HAVING CHARACTERISTICS WITHIN SPECIFIED LIMITS ARE INTERCONNECTED TO FORM AN INTEGRATED CIRCUIT OR ARRAY. A MASK INDICATING THE POSITION OF DEFECTIVE DEVICES OR CELLS IS UTILIZED WITH CONVENTIONAL PHOTOLITHOGRAPHIC TECHNIQUES TO PROVIDE A PATTERN FOR CONNECTIONS BETWEEN ONLY THOSE DEVICES MEETING THE SPECIFIED REQUIREMENTS.

Threshold Investigation of Phase-Locked Discriminators

Abstract: This paper is primarily an investigaton of a second-order phased-locked loop in the threshold region, with the loop filter chosen as (1/1+?s) or (1+?1s/1+?s). First-order loop results are also given. Effects of loop parameters, detuning error, and modulation are studied. It is shown that the loop with filter (1+?1s/1+?s) can be built two ways with same bandwidth and damping. One loop gives much better threshold than the other. The analytical results are supported by computer simulation as well as experimental work obtained by hardware simulation of the loop.