Analog Devices,inc.

Analog Devices Global

Elizabeth A Lillis

John Anthony Cleary

Patrick Joseph Pratt

Eoin Edward English

Evaldo M Miranda, Jr

Christian Steffen Birk

Jan Crols

Kathleen Embrechts

Wim Rens

Russell John Williamson

David Sayago Montilla

Padraig O'Connor

Embodiments of the present invention may provide a method of measuring an unknown capacitance of a device. The method may comprise the steps of driving a test signal to a circuit system that includes a current divider formed by the device with unknown capacitance and a reference capacitor; mirroring a current developed in the reference capacitor to a second circuit system that includes a measurement impedance; measuring a voltage within the second circuit system; and deriving a capacitance of the unknown capacitance based on the measured voltage with reference to a capacitance of the reference capacitor and the measurement impedance.

Capacitance measurement

A method of synchronizing a pulsed drive signal applied to a DC fan motor to the TACH output of the motor is described. DC motors include a rotor that rotates in a path defined by a plurality of magnetic poles and the method defines an ideal TACH output for a specific rotation speed of the rotor of the DC fan and changes the period of the drive signal if the monitored TACH output does not match the ideal TACH output such that the period of the drive signal matches the time taken for the fan to rotate through one magnetic pole of the fan.

Fan speed control

A switched current temperature sensing circuit () comprises a measuring transistor (Q) which is located remotely of a measuring circuit () which applies three excitation currents (I,I,I) of different values to the measuring transistor (Q) in a predetermined current sequence along lines (). Resulting base/emitter voltages from the measuring transistor (Q) are applied to the measuring circuit () along the same two lines () as the excitation currents are applied to the measuring transistor (Q). Voltage differences &#x394;Vof successive base/emitter voltages resulting from the excitation currents are integrated in an integrating circuit () of the measuring circuit () to provide an output voltage indicative of the temperature of the measuring transistor (Q). By virtue of the fact that the measuring transistor (Q) is excited by excitation currents of three different values, the effect of current path series resistance in the lines () on the output voltage indicative of temperature is eliminated. The predetermined current sequence in which the excitation currents are applied to the measuring transistor (Q) is selected to minimize the voltages in the integrating circuit () during integration of the voltage differences &#x394;V.

Method and a measuring circuit for determining temperature from a PN junction temperature sensor, and a temperature sensing circuit comprising the measuring circuit and a PN junction

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Athlunkard, Ireland

Elizabeth A Lillis