Motorola Corporation

Continental Automotive Systems Corporation

Walter S Czarnocki

William J Roeckner

Kevin S Moran

Timothy T Rueger

Peter W Harper

Steven W Alexander

Thomas J Walczak

Xiaoyi Ding

Neal W Hollenbeck

Carl A Ross

John Patrick Schuster

William M Rathke

Kyle Joseph

Thomas Peichl

An automotive sensor reads from memory previously stored back-calculated diagnostic-code values for which a fixed cyclic-redundancy-check ('CRC') value is valid and transmits the previously stored back-calculated diagnostic-code values read from memory each paired together with the fixed CRC value.

Efficient use of CRC with limited data

A method and media-isolated absolute pressure sensor apparatus includes a first sensor () to measure a pressure difference between an isolated media (P) and a second media (Pa). A second sensor () measures an absolute (relative to vacuum) pressure of the second media (Pa). Each sensor () has its own offset and slope response. An equalizer () matches the slopes of the sensors (), wherein a summing circuit () can add the substantially same slope outputs to provide an output signal () indicative of an absolute pressure measurement of the isolated media (P). Offset and temperature compensation of each sensor can also be provided.

Media isolated absolute pressure sensor

A multiple element sensor for sensing pressure, the sensor has a substrate,with a diaphragm portion,Multiple sensing elements,are each disposed on the diaphragm portion,of the substrate,These sensing elements,each have output terminals,providing signals,indicative of the pressure. A combining circuit,has input terminals,each coupled to the output terminals,of each of the sensing elements,respectively. The combining circuit,has a combined output terminal,for providing an output signal,dependent on the plurality of signals,By fabricating this structure different pressure sensor ranges can be selected depending on how many of the sensing elements,are selected by the combining circuit

Multiple element pressure sensor having a selectively pressure sensor range

A sensor (10) includes a plurality of sensing elements (14-20) deposed on a sensor substrate (12) and an electronic switching circuit (22) electrically connected to each of the sensing elements (14-20) for electrically selecting at least one of the sensing elements (14-20).

Selectable pressure sensor

An electronically calibrated sensor (100) includes a sensing element (102) with an output coupled to a signal conditioning circuit (104). The signal conditioning circuit (104) is adapted to be highly computationally efficient and operable for compensating for temperature and part-to-part variation on the sensing element output for providing a useable sensor output signal. The signal conditioning circuit (104) includes an analog-to-digital/digital-to-analog (ADC/DAC) conversion device (112). The ADC/DAC (112) is operable to perform both analog input signal analog-to-digital conversion and digital output signal digital-to-analog conversion. The ADC/DAC (112) is further adapted to provide analog control signals to input signal conditioning circuits (104, 106).

Signal conditioning circuit including a combined ADC/DAC, sensor system,

A polynomial calculator device is applied to calibrate a sensing device. Preferably the sensing device (100) includes a sensing element (102) with an output coupled to a signal conditioning circuit (104). The signal conditioning circuit (104) is adapted to be highly computationally efficient and operable for compensating for temperature and part-to-part variation on the sensing element output for providing a useable sensor output signal. A calibration method relies on a unique polynomial calculator (118) that is implemented as part of the signal conditioning circuit (104). The sensor is preferably manufactured and packaged prior to calibration so as to avoid any post-calibration processing error. The packaged sensor is calibrated and a number of calibration values are retained in a memory (114) and accessed by the calibration method during sensing element signal processing.

Polynomial calculator device, and method therefor

A current reference (10) includes first and second connected resistors (R1 and R2), a voltage source (12) independent of a supply voltage (Vdd). The voltage source is applied to the first and second resistors (R1 and R2) and has a positive temperature coefficient (TC). The first resistor (R1) has a TC less than the voltage source (12) TC and the second resistor (R2) has a TC greater than the voltage source (12) TC. A resistance value of each of the first and second resistors (R1 and R2) is set such that a combined TC of the first and second resistors (R1 and R2) is essentially equal to the voltage source (12) TC such that the current reference (10) produces a current essentially independent of a temperature of the current reference (10) and the supply voltage (Vdd).

Temperature independent current reference

An amplifier circuit (20) having independent gain and response time adjustments includes an amplifier (22), a response time resistor (30), a variable gain resistor (32) attached to the response time resistor and to an output of the amplifier (22), a response time capacitor (34) connected in parallel to the response time resistor (30), an anti-gain resistor (36) connected to a response time (30) and variable gain resistor (32) and to ground, and an input resistor (38) connected to the response time resistor (30) and to in input terminal of the amplifier (22). The response time resistor has a substantially greater resistance value than a resistance value of the variable gain resistor (32) for allowing a gain adjustment of the amplifier circuit (20) without changing the response time of the amplifier (22).

Amplifier circuit having independent gain and response time adjustments

A ratiometric circuit (40) includes a differential capacitive sensor (42) for sensing a change in capacitance, a differential capacitive detector (46) operatively connected to the differential capacitive sensor for detecting a change in the capacitance of the differential capacitve sensor, an error voltage generator (48) operatively connected to the differential capacitve detector for generating a corrective voltage in response to the detected change in capacitance, and a bias circuit (50) operatively connected to the differential capacitive sensor for generating a bias voltage inversely proportional to and independent of a supply voltage for maintaining the ratiometricity between an output voltage of the differential capacitive sensor and the supply voltage.

Ratiometric circuit

A media-isolated differential pressure sensor apparatus and corresponding method combines a first signal (207, 209) provided by a first pressure sensor (101), indicative of a difference between a first pressure and second pressure applied across the first pressure sensor, and a second signal (213, 215) provided by a second pressure sensor, indicative of a difference between the second pressure and a third pressure applied across the second pressure sensor (103) to form a differential pressure sensor. Responsive to a pressure span the first signal (207, 209) responds with a slope response different than a slope response of the second signal (213, 215). A slope adjustment circuit (217) enables an adjustment of the slope response of the first signal (207, 209) to correspond to the slope response of the second signal (213, 215), and provides a slope adjusted first signal (221) dependent on the adjusted slope response. A difference circuit (225) provides an output signal (227) dependent on a difference between the slope adjusted first signal (221) and the second signal (223), where the output signal (227) is indicative of a pressure differential sensed between the first pressure sensor (101) and the second pressure sensor (103).

Gain-adjusting circuitry for combining two sensors to form a media

A pressure sensor circuit (10A) is disclosed which preferably utilizes a piezoresistive pressure transducer (11A) having a substantial temperature coefficient of resistance to provide an inherent temperature variation which is used to implement offset temperature compensation for the circuit. Two operational amplifiers (OA1, OA2) are configured along with selectable resistors (R.sub.1, R.sub.9, R.sub.7, R.sub.8, R.sub.5, R.sub.6 and R.sub.4) to implement four adjustments of the circuit (10A) to adjust span (gain), offset and temperature variation of both span and offset to achieve a desired result. All this is achieved while implementing a common mode gain for the circuit (10A) which is less than 5 and preferably no more than 2.

Pressure sensor circuit

In a calibration circuit for calibration of the output of a differential sensor, signals adjustable in gain for calibration are summed with potentiometrically derived signals for offset calibration to provide a single ended output. Additionally, a signal dependent upon a parameter in respect of which the sensor is unwantedly dependent is summed so that the unwanted response may be compensated. This additional signal is also arranged for calibration in gain and offset so that the unwanted response is calibrated out. The range of calibration includes a null point where there is no response in respect of one parameter to permit calibration in respect of another without interaction.

Multi-variable sensor calibration

Pressure sensor circuit (12) develops an input sensor signal (V01) varying linearly as a function of sensed pressure (P) over a range (P.sub.1) of pressure. An error reduction circuit (14-21, R10-R14) having operational amplifiers (16, 19) and a semiconductor device (21) receives the input sensor signal and provides an output signal (V.sub.OUT). The output signal varies at a first high constant rate during a first portion (P.sub.2) of the pressure range and at a lower constant rate during a second portion (P.sub.3) of the pressure range. A break point (BP) between the first and second pressure range portions occurs when the input sensor signal magnitude exceeds a voltage level (V.sub.T) magnitude. The rate of change of the output signal during the first pressure range portion exceeds the rate of change of the input sensor signal during this same pressure range and thus the percentage of error of the output signal is less during the first pressure range portion than the percentage of error of the input sensor signal. The break point and rates of change of the output signal are substantially temperature independent and each can be independently adjusted.

Non-linear conversion of input from a sensor to an output with two

A mass fluid flow sensor is disclosed which utilizes a sensing bridge circuit to develop a sense (control) signal related to fluid flow. A fluid temperature variable resistor, separate from said bridge circuit, is utilized to implement temperature compensation so that a desired output signal is a function of sensed fluid flow, but is less dependent on fluid temperature than the sense (control) signal provided by the bridge circuit. A resistor in the bridge circuit is selected such that the sense (control) signal provided by the bridge circuit has a rate of change as a function of flow rate substantially independent of fluid temperature, but this sense signal still varies as a function of fluid temperature. This permits fluid temperature compensation of the bridge sense signal in a noncomplex and cost effective manner. An improved adjustable circuit (36-41) is provided for producing a desired temperature variable output signal (V.sub.os).

Adjustable temperature variable output signal circuit

A mass fluid flow sensor is disclosed which utilizes a sensing bridge circuit to develop a sense (control) signal related to fluid flow. A fluid temperature variable resistor, separate from said bridge circuit, is utilized to implement temperature compensation so that a desired output signal is a function of sensed fluid flow, but is less dependent on fluid temperature than the sense (control) signal provided by the bridge circuit. A resistor in the bridge circuit is selected such that the sense (control) signal provided by the bridge circuit has a rate of change as a function of flow rate substantially independent of fluid temperature, but this sense signal still varies as a function of fluid temperature. This permits fluid temperature compensation of the bridge sense signal in a noncomplex and cost effective manner.

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Schaumburg, IL, United States of America

Walter S Czarnocki