National Semiconductor Corporation

Qing Feng Ren

Mehmet Aslan

Richard Dean Henderson

Chungwai Benedict Ng

Hideya Oshima

Dan D'Aquino

Eric Tam

Michael Wong

A circuit for temperature sensing provides a bias current to a PN junction, and the PN junction provides a PN junction voltage in response to the bias current. Also, a parasitic resistance may be coupled in series with the PN junction. The circuit for temperature sensing is configured to determine the temperature of the PN junction based on the PN junction voltage. Further, the circuit includes registers which store &#x3b7;trim, which is based on the difference between the non-ideality of the PN junction used from a reference PN junction; &#x394;I, which is based on the difference between a reference bias current and the bias current for the part; Rtrim, which is based the parasitic resistance; and Ntrim, which includes other offsets. The registers may be set during trimming and/or calibration to provide accurate temperature sensing for the parameters employed.

Apparatus and method for calibration of a temperature sensor

A temperature measurement circuit for a dual junction temperature sensor is provided. The temperature measurement circuit is configured to provide separate bias currents to the junctions in the temperature sensor. The temperature measurement circuit includes two signal channels configured to provide an intermediate differential signal from a differential input signal that is received from the temperature sensor. Also, the temperature measurement circuit may include one or more multiplexer circuits that are configured to control the intermediate differential signal. The temperature sensor circuit further includes a control circuit configured to adjust the bias currents and to control the multiplexer circuits such that several different differential voltages can be provided by the signal channels. Additionally, the temperature measurement circuit includes a conversion circuit that is configured to convert the differential voltage to a temperature signal, and to perform error cancellation based on the different differential voltages provided by the signal channels.

Apparatus for error cancellation for dual diode remote temperature sensors

A method and apparatus improves the accuracy of temperature measurements by sampling measurements from a remote sensor, where currents of different current densities are applied to the remote sensor in a time-interleaved fashion. The remote sensor includes at least one PN junction that produces a voltage corresponding to the applied current at each instance of time, and related to the temperature of the remote sensor. By applying time-interleaved current densities to the remote sensor, adverse effects from temperature variations during the measurement are minimized. Sequences of current biases having differing current densities in a forward order are applied to the remote sensor, followed by the same sequence being applied to the remote sensor in a reverse order. Similarly, a random or pseudo-random sequence may be employed in a forward and reverse order. The application of forward and reverse sequences is utilized to minimize errors in the temperature measurement.

Time-interleaved sampling of voltages for improving accuracy of temperature remote sensors

The present invention is directed to a buffer having dual thresholds. The buffer has an input terminal and an output terminal and comprises a current source, first through fourth transistors, a current mirror, and an output driver. The buffer uses an &ldquo;analog&rdquo; topology to achieve accurate buffering when the thresholds of applied signals are not centered about the mid-supply range. The buffer is useful (among other circuits) in analog and mixed circuit integrated circuits that have relatively high voltage supply levels and signals having logic thresholds that are not centered about the mid-supply level. The buffer uses feedback from the output to achieve hysteresis.

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San Jose, CA, United States of America

Qing Feng Ren