Abstract: A system for balancing current in a circuit is provided.

Abstract: An adjustable voltage controlled oscillator has an input for receiving a voltage signal and an integrator coupled to the input for generating a ramp signal. The circuit also includes an adjustable current supply coupled to an output of the integrator for supplying an adjustable amount of current. A comparator compares the ramp signal with a predetermined voltage. The circuit further includes an output for generating a frequency output as a function of the comparison, wherein the circuit is calibratible by adjusting current generated by the adjustable current supply.

Abstract: An amplifier circuit and method of providing diagnostic testing to a Wheatstone bridge amplifier circuit are provided herein. The amplifier circuit includes a balanced circuit such as a Wheatstone bridge employed in a piezoresistive transducer which produces a differential output signal. The amplifier circuit also includes an amplifier having a differential input for amplifying differential input signals. A diagnostic test circuit is coupled between the balanced circuit and the amplifier circuit and includes a pair of resistors with current sources which may be switched in via electronic switches. With the current sources switched in, a known offset voltage is applied across the differential input to the amplifier and the amplifier output is monitored and compared to an initial output signal. By comparing the initial output signal with the test signal, a determination as to the gain and other characteristics of the amplifier circuit can be made.

Abstract: In accordance with the teachings of the present invention, a temperature dependent voltage generator circuit is provided for generating an output voltage that changes proportionally with changes in the operating temperature of the temperature dependent voltage generator circuit. The temperature dependent voltage generator circuit includes binary weighted current sources and electronic switches that are selectively closed in order to produce a binary weighted current. The binary weighted current is adjustable such that the output voltage of the temperature dependent voltage generator circuit may be "nulled" or forced to zero at any given operating temperature.

Abstract: A temperature dependent signal compensation signal for generating a dual sloped calibration signal is disclosed. The temperature compensation circuit may be coupled to an integrated transducer amplifier circuit that applies the compensation signal for reducing error generated by changing operating temperatures. The signal compensation circuit provides for independent adjustment of the slope of the dual sloped compensation signal in response to changes in the operating temperature of the signal compensation circuit. A technique for generating and adjusting the slope of the dual sloped compensation signal in response to the operating temperature exceeding and falling below a first operating temperature is also disclosed.

Abstract: A programmable current mirror circuit suitable for incorporation into circuit designs and programmably tailored to produce a ratio of current output over current input based upon the status of a plurality of binary weighted switches. The resulting circuit is readily tailored so as to be insensitive to the "on" characteristics of the switches. Alternatively, the switches may comprise transistors controlled by accompanying circuitry operable to produce an equivalent switching function. An input current divider circuit network formed from an array of current mirrors fractionally divides an input current into a plurality of equivalent currents. A binary weighting circuit receives such fractional input currents, and applies a binary weight to each of same. A voltage to current converter receives the binary weighted voltage and converts the voltage to a weighted output current proportional to the input current directly in relation to the binary weighting applied via the binary weighting circuit.

Abstract: A "zener-zap" memory cell with pretest capability for testing effects that would be realized from permanently programming the memory cell is provided. The memory cell is addressable and provides a binary signal at an output. The memory cell uses a zener diode as a memory element which is permanently programmed when selectively coupled to a programming voltage which exceeds the reverse breakdown voltage of the zener diode. The memory cell has a test circuit for generating the programmed binary signal at the output of the memory cell prior to permanently programming the zener diode and when coupled to a pretest voltage.

Abstract: In accordance with the teachings of the present invention, a programmable integrated transducer amplifier circuit is provided which receives differential outputs from a transducer, such as a pressure or accelerometer transducer. The programmable integrated transducer amplifier circuit includes binary adjustable circuits that are programmed in response to binary coded signals. The binary adjustable circuits generate binary weighted currents that are employed to adjust the operating characteristics of the amplifier circuit. The binary coded signals are received from a programmable memory array which includes a plurality of memory cells that store binary information. Each of the memory cells are programmed when coupled to a programming signal. Additionally, the memory array has pretest capability for testing outputs of the memory cells prior to permanently programming the respective memory cells.

Abstract: A stackable voltage comparator circuit that may be used in an analog voltage address decoder circuit for performing voltage window comparisons. The voltage comparator circuit includes a plurality of voltage comparator circuit cells, each of which includes a differential input stage made up of a pair of transistors which receives a current source. A first comparator circuit cell includes a differential input pair of transistors with one of the transistors having a first collector and a second collector, with the second collector being coupled to an output line. The first comparator circuit cell compares an input window with a first threshold voltage and produces an output at the output line. A second comparator circuit cell compares the input voltage with a second threshold voltage and includes a second differential input pair of transistors.

Abstract: A band-gap voltage regulator having a self-regulating characteristic which improves the operation of the regulator includes a feedback circuit coupling a gain stage of the regulator to a voltage reference circuit which influences the regulated voltage. Changes in the operation of the gain stage which would otherwise change the regulated voltage produce counteracting changes in the voltage reference circuit, causing the supply voltage to remain substantially constant.

Abstract: An apparatus for developing a signal voltage that represents the angular position of the crankshaft of an internal combustion engine. The apparatus includes a variable reluctance sensor that has a pick-up coil. The sensor is associated with means driven by the crankshaft of the engine for causing an alternating voltage to be induced in the pick-up coil as the crankshaft rotates. The apparatus includes a negative voltage clamp which clamps the voltage of a junction of the clamp circuit to substantially ground potential during negative half-cycles of the alternating voltage induced in the pick-up coil. The clamp circuit is adapted to be connected to a control circuit that is an integrated circuit having a bulk substrate diode. The clamp circuit prevents forward biasing of the bulk substrate diode.

Abstract: An adjustable temperature dependent current generator includes a transconductance current multiplier, a current mirror, two temperature dependent current generating circuits and a current source to generate currents capable of having an adjustable linear relation to temperature.

Abstract: An operational amplifier of the folded cascode type is disclosed and includes a differential input stage, connected with a differential to single ended output stage, a current mirror is interconnected with both stages for maintaining a precise relationship between bias current in the two stages.

Abstract: A temperature compensation circuit for a device with a voltage output affected by temperature in a predetermined manner and a null output for which the voltage is zero regardless of temperature comprises a voltage to current converter responsive to the generated voltage to produce a proportional current, a current generator comprising elements responsive to the temperature of the device to generate a pair of compensation currents varying therewith in a predetermined manner so that the ratio of the compensation currents embodies a desired temperature compensation, and a transconductance multiplier effective to multiply the proportional current by the ratio of the compensation currents to generate a compensated output current. It may further comprise a current to voltage converter responsive to the compensated output current to produce a compensated output voltage.

Abstract: A bipolar integrated circuit differential voltage to current converter comprises a current source and a current sink at a lower current with two parallel branches connected therebetween. Each branch comprises, from the current source, a resistor, an input transistor with an emitter connected to the resistor and a mirror transistor with an emitter connected to the current sink. The resistors have equal resistance; the input transistors have bases comprising a differential voltage input; and the mirror transistors are connected in a current mirror arrangement. An output current is taken from the junction the resistor and the emitter of the input transistor connected thereto on the output side of the mirror so as to allow the current mirror to maintain equal currents and thus equal base/emitter voltages in the input transistors.

Abstract: A pressure sensor includes a three part package including a housing member defining two spaced-apart chambers, a bottom member providing the bottom wall of one of the chambers, and a top cover member hermetically sealing the two chambers from one another and including a port for admission of gases into one of the chambers. A pressure sensing element is disposed in the chamber having the port and mounted on the bottom member, and a signal processing element is mounted in the other chamber. Electrical connections between the two elements are by means of leads which extend into each chamber and pass through a wall separating the chambers. A low temperature differential between the two elements is provided by extending one of the leads from the other one chamber to a position directly underlying and in intimate contact with the bottom surface of the processing element in the other chamber.

Abstract: A concentric collector PNP transistor is utilized in electrical circuits to determine when the voltages of different parts of a circuit are very close to each other. The transistor has an emitter zone, an inner collector zone that surrounds the emitter zone and an outer collector zone that surrounds both the emitter zone and the inner collector zone. When the voltage of the emitter is slightly higher than the voltage of the inner collector a signal is developed at the outer collector which is used as a trigger or control signal. An oscillator-voltage doubler circuit and a series pass voltage regulator circuit are disclosed that utilize the concentric collector transistor.

Abstract: An operational amplifier includes a PNP differential amplifier operable for low common mode input voltages and an NPN differential amplifier operable for high common mode input voltages so that the operational amplifier is operable over a range of common mode input voltages that includes substantially the positive and negative supply voltages.

Abstract: A temperature stabilized voltage reference is generated based on the difference in the base to emitter voltages of a pair of transistors operating at different current densities which is summed with a voltage that is a predetermined fraction of one of the base emitter voltages. This voltage is utilized to provide for a constant current through a load by adjusting the current through a sense resistor to the value of the temperature stabilized voltage.

Abstract: A multiple input window detector is disclosed which includes a balance pair of common base PNP transistors having multiple emitters connected to respective inputs for comparing either input to an upper threshold level established by a voltage divider. A pair of common emitter PNP transistors compare the inputs to a lower threshold level. The two outputs of each comparator are interconnected and the combined currents control an output stage which is driven to one state when both inputs are within the window established by the divider and is driven in the other state if either input is outside the window.