Abstract: A track-and-hold circuit that consists of an operational amplifer wherein the same capacitors are used for phase compensation and as differential holding capacitors. The circuit is switched from track to hold by turning off the input stage by reverse biasing base-emitter junctions through current steering in combination with resistor clamping. Low impedance during the hold mode is maintained because one half of the differential compensation path is connected to the output. Feed-through is eliminated by cascoding the first stage and turning off the cascode devices through current steering with resistor clamping during the holding mode. The holding capacitors' droop due to bias currents is minimized by current cancellation of the second stage.

Abstract: A technique for reducing phase shift of a signal passing through a large thin film resistor on an insulating layer includes applying a signal to one terminal of the thin film resistor and also to one end of an underlying doped epitaxial region. The opposite terminal of the thin film resistor is connected to a virtual ground or virtual reference voltage produced by an inverting input of an operational amplifier. The corresponding opposite end of the epitaxial layer is connected to ground or other reference voltage. The voltage gradients produced by currents flowing through both the thin film resistor and the epitaxial layer are equal, so that substantially no incremental charging current flows through capacitance between the thin film resistor and the epitaxial layer. Phase shift of the signal flowing through the thin film resistor is thereby avoided.

Abstract: An isolation amplifier includes a voltage-to-duty-cycle modulator, a non-galvanic isolation barrier, and a demodulator converting a duty-cycle-modulated signal transmitted across the isolation barrier to an analog voltage replica of the analog input voltage. The modulator circuit includes a first current switching means which produces a first current that is switched between positive and negative values in response to an output from a comparator that can be referenced to a noise-synchronized signal. The first current is summed with an input current and the difference is integrated and input to the comparator, the output of which produces the duty-cycle-modulated signal.

Abstract: A two-terminal temperature-compensated current source includes a first transistor having its emitter connected to a first terminal, its base connected to the base of a second transistor, and its collector coupled to a current mirror. The second transistor has its emitter coupled to the first terminal by a first resistor and its collector coupled to the current mirror. A second resistor is coupled between the first terminal and the base of the first transistor. The current mirror is coupled between a second terminal and the collectors of the first and second transistors so that all current supplied to the current mirror from the second terminal flows into the collectors of the first and second transistors. A third transistor has its base coupled to the collector of the first transistor, its emitter coupled to the base of the first transistor, and its collector coupled to the second terminal.

Abstract: Method and apparatus for minimizing unpredictable sources of noise, or error voltages, at the microvolt level in precision analog components such as operational amplifiers is described. Sources of such error voltages are temperature gradients across the dice of the precision components enclosed in a hermetically sealed package, thermoelectric voltages caused by temperature differences between junctions of leads of the package with other metals, and light reflected from the substrate through the glass seals around the leads in the base of such packages. A skirted heat sink is positioned in thermal contact with the sides of the package which package is mounted on a substrate. The heat sink transfers heat from the heat sink to its ambient environment by radiation and convection to maintain the temperature within the package substantially constant.

Abstract: An isolation amplifier circuit is described that utilizes a magnetic field in combination with a Hall effect device to isolate input signals and output signals. The input signal is applied to a conducting coil that produces a magnetic field in a Hall effect material through which current is flowing. Because of the Hall effect, terminals on the sides of the Hall effect material can provide a voltage difference. This voltage difference is amplified and applied to a second conducting coil. The second conducting coil is adapted to provide a magnetic field in the opposite direction from the magnetic field produced by the input signal. When the magnetic fields are identical, no difference in current flowing through the two terminals will be present. The output signal of the difference amplifier circuit will be a function of the input signal. According to a second embodiment, apparatus is included for cancelling ambient magnetic fields.

Abstract: A ladder network includes a plurality of cascaded prototype network sections connection in cascade and terminated with a termination resistor. The sections each provide gains of 1/2, 2/5, 1/5 and 1/10. Linear circuits are also disclosed which utilize at least one amplifier and the ladder network in a feedback loop.

Abstract: Means and method is disclosed for achieving a low profile optical coupling to a module comprising an optoelectronic device together with other circuitry. Maintaining the optoelectronic device parallel to the substrate on which it and the associated circuitry are mounted enables the use of standard, well known manufacturing assembly techniques while providing electrical connection to the electric ports of said optoelectronic device. Subsequent to the electrical interconnection operation, the optoelectronic device is moved, together with its connections, to a position substantially orthogonal with the mounting substrate. Optical fiber, light coupling is utilized. The low profile of the overall module package is achieved by introducing the optical fiber in a direction generally parallel with the substrate and perpendicular to the light active surface of the optic port of the optoelectronic device.

Abstract: Means and method for achieving a low profile optical coupling to a planar mounted optoelectronic device. Maintaining the optoelectronic device planar to the substrate on which it and associated circuitry are mounted enables the use of standard, well known manufacturing assembly techniques while providing electrical connection to the electric ports of said optoelectronic device. Optical fiber, light coupling is utilized. The low profile of the overall package is achieved by introducing the optical fiber on a plane which is generally parallel to the light-active surface of the optic port of said optoelectronic device. Actual optical coupling is achieved by introducing a smooth radius bend in the optical fiber so as to bring the fiber and the light-active surface of the optoelectronic device into generally orthogonal relationship. A glass-to-metal seal is provided where the optic fiber enters the package so as to provide a hermetic seal.

Abstract: A molded dual in line package is disclosed which has at least one cavity in a first major molded surface thereof into which an integrated circuit chip can be mounted and wire bonded. After the circuit is tested and adjusted, the cavity is sealed with a metal plate. Other embodiments are disclosed which include a second cavity in a second major molded surface of the package which may house or contain a second integrated circuit, an epoxy sealer, or a substrate.

Abstract: This disclosure relates to a housing or enclosure for an electronic component such as a hybrid module to provide RF shielding therefor. The RF shield has a gap separating two parts of the housing or enclosure to provide D.C. isolation between input and output electrical grounds. In one embodiment, the gap is attained by positioning a split metal sheet or layer within dielectric material such as an inner and outer layer of plastic material. Thus, the gap between the split portions of the RF shield is fixed, set or positioned during the formation of the sandwich dielectric-metal-dielectric structure. The gap has a very narrow spacing to obtain optimum RF shielding while still providing D. C. isolation. The dielectric material in the gap between the two split metal portions of the RF shield prevents electrical arcing between the split portions. In another embodiment, a dielectric, gap forming and metal holding (and separating) member is used to separate the two metal portions of the RF shield.

Abstract: A complementary transistor output circuit and method incorporates an optical coupler including a light emitting diode and a phototransistor connected between the base electrodes of a complementary pair of output transistors including a PNP transistor and an NPN transistor. The emitter of each of the output transistors is connected to an output of the output circuit. The base electrodes of the PNP output transistor and the NPN output transistor are connected, respectively, to first and second current source circuits. The collector electrode of the NPN output transistor is coupled by means of a first feedback circuit including a first resistor and a PNP transistor to the anode of a light emitting diode. The collector electrode of the PNP output transistor is coupled by means of a second feedback circuit to include a second resistor and an NPN transistor to the cathode of the light emitting diode.

Abstract: An optical coupling system is described incorporating a light emitting semiconductive device mounted on a substrate having an electrically conductive strip leading to and from the device. A plurality of photo detector, semiconductive devices are mounted on the substrate adjacent to and co-planar with the light emitting device. A housing is mounted over the semiconductive devices and is filled with a clear light transmitting resin; the interior surfaces of the housing are light reflecting so that light emitted by the light emitting semiconductive device is reflected and diffused therefrom impinging upon each of the photo detector, semiconductive devices.