Cardiac Pacemakers, Inc.

Suneel Arora

David W Kelly

William J Linder

Michael W Dooley

Terrence L Marshall

A current and temperature compensated voltage reference circuit uses a power supply voltage as low as 1.3 Volts. A folded-cascode amplifier measures the temperature dependent voltages provided by first and second bias circuits, each including two series-coupled diodes or diode-connected bipolar junction transistors (BJTs), and provides a resulting proportional to absolute temperature (PTAT) current through a cascode-protected output transistor. A voltage reference circuit uses a PTAT current through a resistor to create a PTAT voltage in series with a diode-voltage. The resistor value is adjusted until the sum of these voltages is equal to the bandgap voltage of silicon, providing a temperature compensated voltage reference. The reference circuit is suitable for use with an implantable cardiac rhythm management system having a battery that provides a power supply voltage varying approximately between 1.3 Volts and 3.25 Volts. Cascode-protected current mirrors further improve rejection of such variations in the power supply voltage.

Current and temperature compensated voltage reference having improved power supply rejection

A voltage regulator in a battery powered device, such as an implantable cardiac defibrillator, provides regulated output voltage for other circuits. When large currents are drawn from the battery, such as during charging of defibrillation output capacitors, switches decouple the regulator from receiving power from the battery and couple the regulator to receive power from a stable boost output voltage generated by a boost converter. The regulator provides a stable regulated output voltage less noisy than the boost output voltage. Controlled switch conductances in the regulator provide operation over a wide range of output load currents.

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Minneapolis, MN, United States of America

Suneel Arora