Analog Devices,inc.

Eric Modica

Derek F Bowers

Edward John Coyne

Apparatus and methods are disclosed, such as those involving a junction field effect transistor for voltage protection. One such apparatus includes a protection circuit including an input, an output, and a JFET. The JFET has a source electrically coupled to the input, and a drain electrically coupled to the output, wherein the JFET has a pinch-off voltage (Vp) of greater than 2 V in magnitude. The apparatus further includes an internal circuit having an input configured to receive a signal from the output of the protection circuit. The protection circuit provides protection over the internal circuit from overvoltage and/or undervoltage conditions while having a reduced size compared to a JFET having a Vp of smaller than 2 V in magnitude.

Junction field effect transistor for voltage protection

To compensate for changes in temperature, a pair of bipolar transistors is connected to a voltage divider and receives a differential voltage that varies with temperature. The voltage divider includes a set of resistors placed in parallel. The set of resistors has a resistance that changes with temperature. As the resistance changes with temperature, the differential voltage provided by the voltage divider changes in proportion to a change in thermal voltage.

Thermal compensation of an exponential pair

In an output stage of an operational amplifier, first and second transistors each provide a collector current under quiescent conditions to first and second current sources. A resistor receives a portion of one the collector currents and produces a resistor voltage in response. An output transistor provides a quiescent current having a value calculated as a function of the resistor voltage and a base-emitter voltage of the second transistor.

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San Jose, CA, United States of America

Eric Modica