Terrence Lemont Marshall

US Patent:

6381491, Apr 30, 2002

Filed:

Aug 18, 2000

Appl. No.:

09/642287

Inventors:

Keith R. Maile - New Brighton MN
Terrence L. Marshall - Minneapolis MN
William J. Linder - Golden Valley MN

Assignee:

Cardiac Pacemakers, Inc. - St. Paul MN

International Classification:

A61N 100

US Classification:

607 2, 327539

Abstract:

A bandgap voltage reference circuit implemented on an integrated circuit chip in which a proportional-to-temperature current is controlled by a current controlling resistor and converted to a voltage by a voltage controlling resistor, with either or both of the resistors being an integrated on-chip digitally trimmable resistor. The reference circuit is particularly suitable for application to circuitry used in implantable medical devices where off-chip resistors provide a channel by which noise can interfere with the operation of the circuit. The on-chip digitally trimmable resistor is implemented in accordance with the invention by a programmable switch matrix connected to a resistor network.

US Patent:

62920502, Sep 18, 2001

Filed:

Mar 1, 1999

Appl. No.:

9/260206

Inventors:

Michael W. Dooley - St. Paul MN
Terrence L. Marshall - Minneapolis MN
William J. Linder - Golden Valley MN
Suneel Arora - Minneapolis MN

Assignee:

Cardiac Pacemakers, Inc. - St. Paul MN

International Classification:

G05F 110

US Classification:

327540

Abstract:

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.