General Electric Company

United States of America As Represented by the Secretary of the Air Force

Walter J Butler

Charles W Eichelberger

Charles M Puckette

Mark B Barron

Bruno F Kurz, Deceased

Miran Milkovic

James R Whitten

By Elizabeth Kurz-Beerli, Executrix, Also Known As Elisabeth H Kurz

A hybrid sensor for simultaneously sensing pressure and temperature in non-interacting manner, includes an insulative substrate having a temperature-sensitive printed thick film resistor fabricated thereon. A conductive plate is insulatively spaced above the resistor and supported by a pressure-tight insulative barrier. The distributed capacitance between the plate and the resistive pattern is a function of the pressure applied to the exterior face of the plate, while the resistance of the resistive thick film is a function of temperature of the surrounding environment.

Pressure and temperature sensor

A charge transfer analog-to-digital converter is provided with means to establish the potential across a large storage well at a comparator threshold voltage at the initiation of a cycle. Charge transfer circuitry is also provided for transferring, into the large potential well, charge packets of size dependent only upon the value of a charge packet capacitance and a scaling voltage. Parasitic capacitance effects are essentially eliminated.

Charge transfer analog-to-digital converter with precise charge control

A charge transfer circuit of the type including first and second capacitors separated by a charge transfer MOSFET is disclosed. The disclosure includes the description of a circuit which compensates for variations in the threshold voltage of the charge transfer MOSFET such that the magnitude of the charge packet transferred from the first to the second capacitor is substantially independent of changes in the magnitude of the threshold voltage.

Charge transfer circuit with voltage threshold compensating means

A reference voltage source, relatively insensitive to changes in ambient temperature and supply voltage, utilizes a plurality of charge transfer amplifiers each having a temperature-stable amplification factor determined essentially by the ratio of two capacitances and independent of temperature-related factors. The amplifiers operate to provide a punch-through reference device with a constant current to cause generation of a stable reference voltage.

Reference voltage source with temperature-stable MOSFET amplifier

A stable temperature-insensitive constant reference voltage circuit is provided which can be implemented in either MOS or bipolar technology. The circuit may be implemented by MOSFET devices on a single chip with another circuit such as an A/D converter to provide a monolithic A/D converter with its own internal reference voltage circuit. The reference voltage circuit consists of a series-connected long channel MOSFET and short channel MOSFET which produce, at their junction, a temperature-independent voltage. A differential circuit containing three MOSFET devices is then provided with one of the devices serving as a current source which carries the current of the other two MOSFET devices which are in parallel. The gates of the two parallel MOSFET devices are connected respectively to the junction between the long channel and short channel device and to the output voltage. Current divides between the two parallel MOSFET devices in such a way as to cause a constant output voltage to be produced regardless of the variations of the supply voltage sources V.sub.dd or V.sub.gg. The various MOSFET devices are formed on the same substrate containing the circuit components being connected to the constant stable voltage reference source.

MOSFET Reference voltage circuit

A charge transfer circuit of the type including first and second charge storage locations and a charge transfer transistor for transferring a plurality of discrete packets of charge from the first to the second charge storage location is disclosed. The charge transfer circuit includes circuitry for compensating for changes in a thermally induced leakage current such that the charge transfer transistor transfers a variable amount of charge from the first to the second charge storage location during each successive charge transfer operation such that the total amount of charge, i.e. the leakage charge plus the transferred charge packet, accumulated by the second charge storage location during each charge transfer operation, is a constant regardless of changes in the temperature or illumination of the transistor. In a second embodiment, changes in the magnitude of the thermally or optically induced leakage current are taken into account by adjusting the magnitude of an analog signal to which the total amount of charge stored in the second charge storage location is compared.

Charge transfer circuit with leakage current compensating means

A monolithic analog to digital converter having leakage current compensating circuitry is disclosed. First and second charge storage capacitors are formed in a single semi-conductor substrate. An analog signal to be converted and a reference signal are simultaneously applied to the first and second capacitors, respectively. Thereafter, a charge transfer circuit supplies the first capacitor with a plurality of discrete charge packets. The polarity of the charge packets is chosen so as to increase or decrease the voltage across the first capacitor in the direction of the voltage across the second capacitor. When the voltage across the two capacitors become equal, a differential comparator generates an output signal indicating the end of a conversion operation. The parameters of the first and second capacitors are chosen such that the amount of charge added to or subtracted from the second capacitor due to a thermally induced leakage current in the substrate is substantially equal to the amount of charge added to or subtracted from the first capacitor as the result of the thermally induced leakage current.

The novel structure disclosed comprises an n-type epitaxial layer on a p.sup.- type substrate with p.sup.+ type top gates diffused into the epi-layer and p.sup.+ buried gates aligned with the source side of the top gates. The top-gate diffusion extends far into the drain region.

Junction-storage JFET bucket-brigade structure

An analog-to-digital converter is described wherein an analog signal is converted to a digital equivalent thereof in a structure suitable for implementation in MOS form. The analog signal is converted to a quantity of charge which is duplicated by summing a plurality of substantially equal sized charge packets in an MOS charge storage location.

A/D Converter

A plurality of capacitive touch pad sensors are multiplexed to the input of a common charge transfer analog-to-digital converter (CTAD) under the control of a control logic circuit. The no-touch digital output of each touch pad is stored in a memory. The touch pads are then sequentially addressed and their output level is digitized in the CTAD and the digital output of each touch pad is compared to its no-touch value stored in the memory. If the digital value read is sufficiently different from the no-touch memorized value, a touch-detection signal is given. The no-touch digital reading in the memory is periodically updated, by a count of only one at most, if the updated no-touch value differs from the no-touch value in the memory.

Self-optimizing touch pad sensor circuit

A time-independent, dual-slope analog to digital converter is disclosed. During a first integration period, a predetermined number of charge packets having a first polarity and a magnitude proportional to the magnitude of an analog voltage to be converted are applied to a charge storage element. The first integration period is followed by a second integration period during which a second plurality of charge packets are applied to the charge storage element. The second plurality of charge packets each have a polarity opposite to that of the first plurality of charge packets and a predetermined, constant magnitude. The number of second charge packets required to return the charge stored in the charge storage element to its original value is indicative of the magnitude of the analog signals to be converted.

Dual-slope analog to digital converter

A charge transfer circuit of the type including first and second capacitors and a charge transfer transistor for transferring discrete packets of charge from the first to the second capacitor is disclosed. The charge transfer circuit includes a feedback circuit which recharges the first capacitor to a value which varies as a function of the threshold voltage of the charge transfer transistor. As a result, the magnitude of the charge packets transferred by the charge transfer remain at a predetermined value irrespective of variations in the threshold voltage of the transistor.

Charge transfer circuit with threshold voltage compensating means

A preamplifier using charge transfer techniques is formed on the same chip as a charge transfer analog to digital converter. The preamplifier then couples low level output sensors directly to the converter without need for a costly interfacing amplifier.

Preamplifier for analog to digital converters

An electronic temperature sensor utilizing monolithic charge transfer circuitry is disclosed. A first charge transfer circuit supplies a charge storage element with N.sub.1 first charge packets, N.sub.1 being the number of charge packets required to change the charge stored by the charge storage element from a first to a second value. A second charge transfer circuit supplies the charge storage element with N.sub.2 second charge packets, N.sub.2 being the number of charge packets required to change the charge stored by the charge storage element from the first to the second value. The magnitude of the second charge packet varies from the magnitude of first packet as the linear function of the temperature to the sensor. A counter generates an output signal which is a function of the difference between N.sub.1 and N.sub.2 and which is indicative of the magnitude of the temperature to be sensed.

Electronic temperature sensor

A solid state cathode driver circuit for controllably sinking a current substantially independent of applied voltage includes a main current carrying transistor and first and second field effect transistors connected to a controlled electrode of the current carrying transistor for setting the potential on the control electrode substantially independent of the applied voltages to the controlled terminals. The magnitude of the sunk current is essentially determined by the geometry of the device utilized and is, therefore, essentially constant. Selective activation of the current sink is provided by grounding the control electrode to turn off the device.

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Scotia, NY, United States of America

Walter J Butler