Abstract: A comparison system compares a voltage which is proportional to absolute temperature S.sub.p to one which is equal to the sum of a conventional, uncorrected, bandgap cell voltage VBG and a proportional to absolute temperature voltage CT. The addition of CT to the uncorrected bandgap signal value yields a signal of the form Sp/(VBG+CT), which exhibits improved linearity over a signal of the form Sp/VBG, where VBG includes a Tln(T) term.

Abstract: An low dropout voltage regulator (LDO) drive reduction circuit detects when the LDO's output voltage is going out of regulation due to a falling input voltage while the output is lightly loaded, and reduces the drive to the pass transistor in response. This action prevents the LDO's ground current from rising unnecessarily. The drive reduction circuitry directly monitors the voltage across the pass transistor; when above a predetermined threshold voltage which is typically well-below the LDO's specified dropout voltage, the pass transistor drive is permitted to vary as necessary to maintain a specified output voltage. If the monitored voltage falls below the threshold voltage, indicating that the input voltage is falling and the output is lightly loaded, the drive reduction circuit reduces the drive current, which would otherwise get increased in an attempt to restore the output voltage.

Abstract: A trimmable voltage regulator feedback network is arranged as a voltage divider: series-connected resistors are connected between the divider tap and the regulator's output voltage and a fixed resistance is connected between the tap and ground. Severable links are connected across at least two resistors above the tap to allow the regulator output voltage to be trimmed in linearly independent increments with each severed link, thereby simplifying the task of determining which links to sever to attain a desired output voltage. A trimmable resistance is inserted between the divider tap and the circuit being driven to enable the impedance of the network to be adjusted. A regulator including the novel feedback network can provide a temperature-compensated output over the full range of selectable output voltages.

Abstract: An inverter circuit, suitably implemented in the feedback loop of a series pass regulator, limits the maximum drive current through an output drive transistor connected to control the regulator's pass transistor. A first current source i1 biases an inverting amplifier that includes a transistor and an output resistor R, which inverts an input signal received from an emitter follower and feeds the inverted signal to an output drive transistor which has its collector connected to the base of the pass transistor. A second current source i2 is connected to allow the inverter's input signal to follow the emitter follower negative. When the follower is cut-off, i2 flows through the output resistor and increases the voltage of the signal fed to the output drive transistor by i2.times.R. The increased voltage establishes a maximum drive current based on i1, i2 and R, which is independent of the betas of the individual transistors.

Abstract: A monolithic capacitance-type microstructure includes a semiconductor substrate, a plurality of posts extending from the surface of the substrate, a bridge suspended from the posts, and an electrically-conductive, substantially stationary element anchored to the substrate. The bridge includes an element that is laterally movable with respect to the surface of the substrate. The substantially stationary element is positioned relative to the laterally movable element such that the laterally movable element and the substantially stationary element form a capacitor. Circuitry may be disposed on the substrate and operationally coupled to the movable element and the substantially stationary element for processing a signal based on a relative positioning of the movable element and the substantially stationary element. A method for fabricating the microstructure and the circuitry is disclosed.

Abstract: A temperature set point circuit employs a pair of bipolar transistors operated at unequal current densities, with the difference between the transistors' base-emitter voltages appearing across a trim resistor connecting their emitters. A pair of trim resistors, one of which may be external to an integrated circuit embodiment of the set point circuit, forms a resistor divider with the inter-base resistor and are selected to produce a desired temperature trip-point.

Abstract: A low drop-out voltage regulator is compensated by providing a compensation capacitor across an output terminal of the regulator and an output lead of an input stage which compares a reference voltage and a voltage derived from a regulated output signal at the output terminal. The output from the input stage is inverted without gain before being provided to an output stage. This inversion allows Miller compensation with the compensation capacitor.

Abstract: A circuit construction for biasing near a pocket containing a power supply potential circuit element in a junction-isolated circuit. In normal operation if the polarity of the supply voltage is reversed from that intended the pocket is disconnected. To achieve this, in one embodiment the emitter of a transistor is connected to the positve supply voltage. The collector of that transistor is used to bias the pocket, containing a circuit element, which in normal operation should receive the supply voltage. When the supply voltage is reversed, the emitter-base junction is reverse biased and the collector-base junction is turned off. The pocket is thus disconnected from the supply during supply reversal. The transistor may also have a second collector to handle reinjection of carriers when it is saturated. This second collector can be connected to the base or used by other circuits to detect when saturation occurs.

Abstract: A resistor programmable temperature switch for indicating that a preselected trip temperature has been reached includes first and second bipolar trasistors of like polarity having a fixed ratio of emitter areas; means for connecting the emitters of the first and second transistors to a common terminal; first and second current sources for providing first and second predetermined currents to the collector of the first and second transistors, respectively; a third transistor; means connecting its control terminal to the first current source and a first load terminal connected to the base of the first transistor for operating the first transistor to conduct the first predetermined current from the current source; means for interconnecting a second load terminal of the third transistor with a power supply terminal; a resistor network including first and second resistors connected between the base of the first transistor and the common terminal for biasing the base of the second transistor to a fraction of the bas

Abstract: An accelerometer comprising a microfabricated acceleration sensor and monolithically fabricated signal conditioning circuitry. The sensor comprises a differential capacitor arrangement formed by a pair of capacitors. Each capacitor has two electrodes, one of which it shares electrically in common with the other capacitor. One of the electrodes (e.g., the common electrode) is movable and one of the electrodes is stationary in response to applied acceleration. The electrodes are all formed of polysilicon members suspended above a silicon substrate. Each of the capacitors is formed of a plurality of pairs of electrode segments electrically connected in parallel and, in the case of the movable electrodes, mechanically connected to move in unison. When the substrate is accelerated, the movable electrodes move such that the capacitance of one of the capacitors increases, while that of the other capacitor decreases.

Abstract: A circuit for varying the temperature of a first bipolar transistor in order to thermally compensate for self-heating effects of an associated device in a common signal path with the first transistor, the first transistor being configured within an isolated collector region. The circuit includes a second bipolar transistor provided within the isolated collector region and thermally coupled to the first transistor, the second transistor operable for providing heat to the first transistor to alter the temperature to a predetermined level, thus changing the operational voltage characteristics of the first transistor so as to minimize shifts in offset voltage.

Abstract: The invention is a monolithic sensor comprising a silicon substrate, a suspended polysilicon microstructure for sensing a condition disposed above and suspended from the substrate, and circuitry for resolving a signal based on said sensed condition, the circuitry including bipolar circuit elements and MOS circuit elements. One disclosed embodiment is particularly adapted for sensing acceleration by means of a differential capacitor arrangement in which one capacitor plate in the arrangement is moveable responsive to an acceleration.

Abstract: A high gain transistor amplifier with internal balancing bias having a common mode input range which includes a supply rail includes a differential to single-ended converting input stage including at least one pair of transistors, each transistor having first and second current terminals and a control terminal; input means for providing an input signal to the first current terminals of the transistors; a voltage amplifier stage for providing an amplified output of the input signal, the voltage amplifier stage including at least one transistor having a control terminal; and a biasing circuit responsive to the voltage amplifier stage for maintaining balanced currents between the control terminal of the voltage amplifier stage and the control terminals of the differential to single-ended converting input stage, the biasing circuit being connected to the second current terminals of each transistor pair and the voltage amplifier stage being connected to one of the second current terminals so that the first termina

Abstract: A two terminal temperature transducer which controls its operating current to indicate the temperature, by producing a linear response to temperature which can be set to extrapolate to a desired temperature. The transducer including circuitry which controls its operating current to be linearly proportional with temperature. The circuitry operates to produce a first reference voltage which is proportional to absolute temperature, produce a second reference voltage which is complementary to absolute temperature, generate a voltage drop corresponding to the operating current, compare the voltage drop to a temperature sensitive voltage corresponding to the difference between the first reference voltage and the second reference voltage, and adjust the operating current so as to equilibrate the voltage drop and the temperature sensitive voltage.

Abstract: An integrated circuit including a comparator having two output states and being responsive to a voltage developed across a shunt in the circuit so that the comparator assumes one of its two output states when the voltage developed across the shunt is greater than a threshold switching voltage and the other of its two output states when the voltage developed across the shunt is less than the threshold switching voltage. The integrated circuit additionally includes a threshold switching voltage sensitivity control circuit, coupled to and controlling the comparator, for controlling a sensitivity of the threshold switching voltage to changes in a supply voltage of the lamp circuit and for controlling a sensitivity of the threshold switching voltage to changes in temperature of the integrated circuit.

Abstract: An accelerometer comprising a microfabricated acceleration sensor and monolithically fabricated signal conditioning circuitry. The sensor comprises a differential capacitor arrangement formed by a pair of capacitors. Each capacitor has two electrodes, one of which it shares electrically in common with the other capacitor. One of the electrodes (e.g., the common electrode) is movable and one of the electrodes is stationary in response to applied acceleration. The electrodes are all formed of polysilicon members suspended above a silicon substrate. Each of the capacitors is formed of a plurality of pairs of electrode segments electrically connected in parallel and, in the case of the movable electrodes, mechanically connected to move in unison. When the substrate is accelerated, the movable electrodes move such that the capacitance of one of the capacitors increases, while that of the other capacitor decreases.

Abstract: An apparatus for monitoring voltage as a function of temperature of a storage battery and an apparatus for controlling the charging voltage of the battery based on battery temperature, voltage, and charging system loads. The battery monitoring apparatus includes a comparator for comparing, at any temperature in the working temperature range of the battery, the actual battery voltage with a reference battery voltage. The reference battery voltage is the voltage gassing curve for the storage battery. The comparator is given a temperature coefficient provided by a temperature-sensitive band-gap voltage reference. A plurality of the temperature-sensitive band-gap reference cells may be connected together in order to accurately track any differently sloped battery gassing voltage curve.

Abstract: A monolithic interface circuit for use with a linear variable differential transformer (LVDT) position transducer. The interface circuit includes a drive circuit for providing an excitation signal of selectable frequency and amplitude to the LVDT primary winding. The interface circuit further includes a decoder responsive to signals induced in the LVDT secondary windings for computing the position p of the LVDT core as a solution to the equation p=K(A-B)/(A+B), where A and B represent the signals induced in the primary winding and K is a constant scale factor. The decoder includes circuitry for rectifying and filtering the secondary signals, a charge balance loop responsive to the detected signals for providing a binary signal having a duty cycle representative of B/(A+B), and an output circuit responsive to the binary signal for providing the position output. The decoder provides excellent scale factor stability and linearity and is relatively insensitive to variations in primary drive amplitude.

Abstract: An apparatus for monitoring current through a lamp circuit that uses a series resistance shunt in the circuit with one end connected to a current source and the second end connected to the lamp. The apparatus includes a comparator that is connected across the shunt and has a threshold switching voltage wherein a voltage across the shunt that is larger than the threshold switching voltage will switch the comparator on and a voltage across the shunt that is smaller than the threshold switching voltage will switch the comparator off. A biasing circuit, connected to and controlling the comparator, temperature compensates the threshold switching voltage such that the threshold switching voltage changes proportionally to absolute temperature and controls a sensitivity of the threshold switching voltage to changes in a supply voltage of the circuit. In a preferred embodiment, the shunt is a portion of the printed board trace.

Abstract: A multiplexed single channel knock sensor signal conditioner system for internal combustion engines includes a plurality of sensors for sensing the vibrations associated with knocking in an internal combustion engine; a single signal conditioning channel for providing a signal level representative of the magnitude of the knock; and means for selectively connecting the sensors to the signal conditioning channel. The signal conditioning channel includes a band pass filter, the frequency characteristics of which are adjusted according to the sensor connected to the signal conditioning channel.