Medtronic, Inc.

Linear Technology Corporation

Samuel Patrick Rankin

Robert C Dobkin

Scott Dennis Vernon

A clamping circuit clamps a voltage received by an n-type semiconductor region without using a Schottky transistor. The clamping circuit includes a current mirror as well as first and second bipolar transistors. The current mirror receives a first current and supplies a second current in response. The first current is received by the first bipolar transistor, and the second current is received by the second bipolar transistor. The difference between the base-emitter junction voltages of the first and second bipolar transistors, in part, defines the voltage at which the n-type region is clamped. To start-up the circuit properly, current is withdrawn from the base/gate terminals of the transistors disposed in the current mirror. The circuit optionally includes a pair of cross-coupled transistors to reduce the output impedance and improve the power supply rejection ratio.

Method for clamping a semiconductor region at or near ground

An integrated current-to-voltage conversion circuit converts a first current to an output voltage representative of the first current. The circuit includes a first contact pad and second and third contact pads capable of being coupled across a first resistor. A first operational amplifier has a first input coupled to the first contact pad for producing a first voltage thereat, a second input for receiving a reference voltage, and a first output coupled to the third contact pad. A second voltage appears at the third contact pad. A second operational amplifier has a second output at which a third voltage appears, a first input coupled to the second output, and a second input coupled to the second contact pad. The output voltage is substantially equal to the difference between the second and third voltages.

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Phoenix, AZ, United States of America

Samuel Patrick Rankin