Abstract: A method and apparatus for measuring the amount of flow of a flowing medium. The method and apparatus include a bridge circuit configured to develop a bridge voltage Vb such that the magnitude of the bridge voltage Vb is indicative of the amount of flow. The bridge circuit is configured without having an ambient temperature sensor, thus the bridge voltage is uncompensated with respect to ambient temperature. A thermistor circuit is configured to generate a temperature reference voltage indicative of ambient temperature. A conditioning circuit is configured to receive the uncompensated bridge voltage and the temperature reference voltage to process the same and generate a compensated bridge voltage with respect to ambient temperature.

Abstract: A method and apparatus for measuring the amount of flow of a flowing medium. The method and apparatus include a bridge circuit configured to develop a bridge voltage Vb such that the magnitude of the bridge voltage Vb is indicative of the amount of flow. The bridge circuit is configured without having an ambient temperature sensor, thus the bridge voltage is uncompensated with respect to ambient temperature. A thermistor circuit is configured to generate a temperature reference voltage indicative of ambient temperature. A conditioning circuit is configured to receive the uncompensated bridge voltage and the temperature reference voltage to process the same and generate a compensated bridge voltage with respect to ambient temperature.

Abstract: A bi-directional mass air flow sensing device for measuring air flow, comprising a bridge circuit coupled across a voltage potential, wherein the bridge circuit comprises a first side including first and second temperature dependent sensor resistors connected in series and disposed on a thermally insulative substrate window in line with an air flow and arranged such that relative to a first direction of air flow, the first sensor resistor is upstream of the second sensor resistor, and a second side in parallel with the first side and including third and fourth temperature dependent sensor resistors connected in series and disposed on the thermally insulative substrate in line with the air flow such that relative to the first direction of air flow, the third sensor resistor is upstream of the fourth sensor resistor, and a temperature dependent balance resistor connected between the first and second temperature dependent sensor resistors on the first side of the bridge circuit.

Abstract: A bi-directional mass air flow sensing device for measuring air flow, comprising a bridge circuit coupled across a voltage potential, wherein the bridge circuit comprises a first side including first and second temperature dependent sensor resistors connected in series and disposed on a thermally insulative substrate window in line with an air flow and arranged such that relative to a first direction of air flow, the first sensor resistor is upstream of the second sensor resistor, and a second side in parallel with the first side and including third and fourth temperature dependent sensor resistors connected in series and disposed on the thermally insulative substrate in line with the air flow such that relative to the first direction of air flow, the third sensor resistor is upstream of the fourth sensor resistor, and a temperature dependent balance resistor connected between the first and second temperature dependent sensor resistors on the first side of the bridge circuit.

Abstract: A mass air flow meter has a time lag which varies according to the air flow rate. A digital filtering method enhances the raw meter output signal by calculating a correction term based on varying time constants which are dependent on the instantaneous raw signal. The correction term is added to the raw signal. Alternatively first and second order time constants are used to calculate first and second order correction terms.

Abstract: A bridge-type "hot wire" flowmeter is temperature compensated by selecting the values of a power resistor, a ballast resistor and a calibration resistor in accordance with an iterative numerical solution of a pair of equations of the form.0.=C5*Ti.sup.5 +C4*Ti.sup.4 +C3*Ti.sup.3 +C2*Ti.sup.2 +C1*Ti+C.0..0.=K2*Tr.sup.2 +K1*Tr+K.0.wherein the ideal temperature Ti to which the self-heated resistor should be heated for ideal temperature compensation and the real temperature Tr to which the self-heated resistor is actually heated are specified to be equal at three predetermined values of ambient temperature within the range over which it is desired to temperature compensate the flowmeter.