Medtronic, Inc.

Applied Micro Circuits Corporation

Vtc Inc.

Qualcomm Incorporated

Polar Semiconductor, Inc.

Robert John Schuelke

Michael T Hemming

Bradley C Peck

Brian A Blow

Scott M Morrison

James D Reinke

James W Busacker

Douglas Warren Dean

Russell E Anderson

Gregory J Rausch

John J Stronczer

Barbara J Schmid

Kevin L Bright

Ren Zhou

David W Hoffman

Virginia De La Riva

Kevin P Beaudoin

Jonathan R Gering

John Anthony Schuler

Crispin K Metzler

A current-mode under voltage lockout (UVLO) circuit provides an output signal that indicates to connected devices whether a connected power supply is sufficient (i.e., of sufficient strength and stability) based on a comparison of a current that is proportional to the power supply and a reference current. The current-based UVLO circuit employs a reference current generator that is capable of providing a stable reference current and a voltage-to-current converter that provides a current proportional to the power supply voltage. A comparator compares the reference current to the current proportional to the power supply voltage and determines based on the magnitudes of the two currents whether the power supply voltage is sufficient or 'good' and generates an output signal indicating the status of the power supply voltage.

Current-mode under voltage lockout circuit

Standardized scan cell logic is enabled to test board-level and circuit-level AC interfaces built into integrated CMOS circuits by verification of high-speed AC coupled non-CMOS logic level signals driven onto non-CMOS logic level AC coupled interconnects in those circuits.

Detection circuit and method for AC coupled circuitry

A laser driver includes two DC-coupled differential drive circuits in which the common mode voltage of the first differential drive circuit is maintained a level affording a high compliance voltage for a laser diode driven by the second differential drive circuit. This is accomplished by means of an operational amplifier which compares the common mode voltage of the second differential drive circuit to a reference voltage. The operational amplifier operates in a closed-loop configuration to draw current through a common mode bias resistor in the first differential drive circuit in order to force the common mode voltage of the second differential drive circuit to a desired value determined by the reference voltage.

High compliance laser driver

A high-speed current mirror and correction circuitry are provided to minimize current errors in short-channel MOS switched current mirrors. The current mirror supplies high current levels at high modulation speeds, while simultaneously exhibiting good output voltage compliance. The correction circuitry includes a buffer amplifier, current shaping circuit, and replica mirror section. The current shaping circuit is able to supply a differential reference current, to correct load current errors, in response to the replica mirror section matching the buffered load voltage.

Output conductance correction circuit for high compliance short-channel MOS switched current mirror

A circuit yielding a precise, programmable, finite temperature coefficient, in the form of either current or voltage, has been provided. Temperature independent and temperature dependent currents are manipulated through the use of digital to analog converters (DACs), with the sum of these currents representing the desired coefficient. The DACs are digitally programmable to provide the exact current required to meet a predetermined temperature coefficient. Electrical components requiring temperature compensation can be precisely controlled by supplying current at a known, predetermined temperature coefficient. A method of digitally programming a current or voltage having a predetermined finite temperature coefficient has also been provided.

Voltage/current reference with digitally programmable temperature coefficient

A software programmable device means such as a microprocessor discriminates between evoked response signals and post-pace polarization signals sensed by an implantable medical device. The polarity of the positive or negative change in voltage in respect of time (or dv/dt) of the waveform incident on the lead electrodes is monitored during a short period of time immediately following a paced event. It has been discovered that the post-pace polarization signal exhibits a relatively constant polarity during the capture detect window, and that the evoked response signal may cause the polarity of post-pace polarization signal to reverse during the capture detect window . The sign of the post-pace polarization polarity, either positive or negative, is determined by the design of the specific output circuitry. The evoked response signal may reverse the polarity of the sensed signal in either case, from positive to negative or from negative to positive, during the time window of interest. In another embodiment of the present invention, and when the magnitude of the post-pace polarization is so great that the evoked response does not reverse the polarity of the waveform, discrimination of the evoked response is achieved by noting an acceleration (or increasing magnitude of dv/dt) in the sensed signal or waveform.

Microprocessor capture detection circuit and method

A method and apparatus for discriminating between evoked response signals and post-pace polarization signals sensed by a sense amplifier of an implantable medical device. The polarity of the positive or negative change in voltage in respect of time (or dv/dt) of the waveform incident on the lead electrodes is monitored during a short period of time immediately following a paced event. The post-pace polarization signal exhibits a relatively constant polarity during the capture detect window, and the evoked response signal may cause the polarity of post-pace polarization signal to reverse during the capture detect window. The sign of the post-pace polarization polarity, either positive or negative, is determined. The evoked response signal may reverse the polarity of the sensed signal from positive to negative or from negative to positive, during the time window of interest. When the magnitude of the post-pace polarization is so great that the evoked response does not reverse the polarity of the waveform, discrimination of the evoked response is achieved by noting an acceleration (or increasing magnitude of dv/dt) in the sensed signal or waveform. In one embodiment, sensing of the evoked response is based upon a relationship between a maximum magnitude of a derivative of a sensed signal and a predetermined threshold reference value. The evoked response is declared when the maximum amplitude of the a derivative of the sensed signal equals or exceeds the threshold reference value.

Capture detection circuit for pulses and physiologic signals

A software programmable microprocessor discriminates between evoked response signals and post-pace polarization signals sensed by an implantable medical device. The polarity of the positive or negative change in voltage in respect of time (or dv/dt) of the waveform incident on the lead electrodes is monitored during a short period of time immediately following a paced event. It has been discovered that the post-pace polarization signal exhibits a relatively constant polarity during the capture detect window, and that the evoked response signal may cause the polarity of post-pace polarization signal to reverse during the capture detect window. The sign of the post-pace polarization polarity, either positive or negative, is determined by the design of the specific output circuitry. The evoked response signal may reverse the polarity of the sensed signal in either case, from positive to negative or from negative to positive, during the time window of interest. In another embodiment, when the magnitude of the post-pace polarization is so great that the evoked response does not reverse the polarity of the waveform, discrimination of the evoked response is achieved by noting an acceleration (or increasing magnitude of dv/dt) in the sensed signal or waveform.

Two mechanisms work together to adjust two variables independently so that the gain of an input amplifier used to find physiologic signals in an implantable medical device can be automatically adjusted to enhance the signal to noise ratio of the electrical input to said amplifier. The first determines whether there has been too long a time between senses found in the body's electrical input to the amplifier and if true, and no other conditions override that consideration, it adjusts the value of a long term average parameter which is used as a referent parameter to adjust the actual parameter that is used as the referent for making either a threshold level adjustment or gain change, depending on the structure of the particular design's circuitry and/or software. One set of adjustments to the gain referent parameter depends on the relative size of the long term average parameter and the gain referent parameter. The mechanisms preferably employ counting registers, the one which adjusts the gain referent having a process to weight input signals such that those of different types get different weights, and the other mechanism only accepting certain of the input signals. Input signals to the two mechanisms can be either physiologically based or from stimulation pulses issued from an implanted device, such as, for example a pacemaker.

Method for automatically adjusting the sensitivity of cardiac sense

A preamplifier bias circuit for use in an AC coupled magnetoresistive read head amplifier which includes a pair of head contacts, a pair of amplifier inputs, a pair of coupling capacitors and a means for selectively shunting the amplifier inputs and rapidly charge the coupling capacitors. The pair of head contacts and the pair of amplifier inputs couple the preamplifier bias circuit to a magnetoresistive element and a read amplifier, respectively. Each of the coupling capacitors is connected between one of the head contacts and one of the amplifier inputs to block a static potential across the magnetoresistive element. The means for selectively shunting the amplifier inputs selectively provides a low impedance path to rapidly charge the coupling capacitors and clamps the amplifier inputs to a known potential. By selectively providing a low impedance path, the AC coupled magnetoresistive read head amplifier can be protected and its associated delay time prior to operation can be decreased.

Preamplifier bias circuit for use in an AC coupled magnetoresistive read

The programmable device means such as a microprocessor are employed to discriminate between evoked response signals and post-pace polarization signals sensed by an implantable medical device. The polarity of the positive or negative change in voltage in respect of time (or dv/dt) of the waveform incident on the lead electrodes is monitored during a short period of time immediately following a paced event. It has been discovered that the post-pace polarization signal exhibits a relatively constant polarity during the capture detect window, and that the evoked response signal may cause the polarity of post-pace polarization signal to reverse during the capture detect window . The sign of the post-pace polarization polarity, either positive or negative, is determined by the design of the specific output circuitry. The evoked response signal may reverse the polarity of the sensed signal in either case, from positive to negative or from negative to positive, during the time window of interest. When magnitude of the post-pace polarization is so great that the evoked response does not reverse the polarity of the waveform, discrimination of the evoked response may be achieved by noting an acceleration (or increasing magnitude of dv/dt) in the sensed signal or waveform.

Software programmable device means such as a microprocessor are employed to discriminate between evoked response signals and post-pace polarization signals sensed by an implantable medical device. The polarity of the positive or negative change in voltage in respect of time (or dv/dt) of the waveform incident on the lead electrodes is monitored during a short period of time immediately following a paced event. It has been discovered that the post-pace polarization signal exhibits a relatively constant polarity during the capture detect window, and that the evoked response signal may cause the polarity of post-pace polarization signal to reverse during the capture detect window. The sign of the post-pace polarization polarity, either positive or negative, is determined by the design of the specific output circuitry. The evoked response signal may reverse the polarity of the sensed signal in either case, from positive to negative or from negative to positive, during the time window of interest. When the magnitude of the post-pace polarization is so great that the evoked response does not reverse the polarity of the waveform, discrimination of the evoked response may be achieved by noting an acceleration (or increasing magnitude of dv/dt) in the sensed signal or waveform.

The present invention permits discrimination between evoked response signals and post-pace polarization signals sensed by an implantable medical device by noting the polarity of the positive or negative change in voltage in respect of time (or dv/dt) of the waveform incident on the lead electrodes during a short period of time immediately following a paced event. It has been discovered that the post-pace polarization signal exhibits a relatively constant polarity during the capture detect window, and that the evoked response signal may cause the polarity of post-pace polarization signal to reverse during the capture detect window. The sign of the post-pace polarization polarity, either positive or negative, is determined by the design of the specific output circuitry. The evoked response signal may reverse the polarity of the sensed signal in either case, from positive to negative or from negative to positive, during the time window of interest. In another embodiment of the present invention, and when the magnitude of the post-pace polarization is so great that the evoked response does not reverse the polarity of the waveform, discrimination of the evoked response is achieved by noting an acceleration (or increasing magnitude of dv/dt) in the sensed signal or waveform.

Peak tracking capture detection circuit and method

A lead integrity measurement system for a cardiac pacemaker/cardioverter/defibrillator (PCD) of the type comprising an implantable pulse generator (IPG) and a lead system including one or more pacing leads each having a proximal end coupled to a pacing terminal of the IPG and a distal end with at least one pace/sense electrode in contact with a patient's heart and a pair of defibrillation leads coupled to defibrillation terminals of the IPG and defibrillation electrodes implanted in relation to the patient's heart. In a lead impedance test mode, the terminal of a selected defibrillation lead under test is coupled to system ground, and an excitation voltage is applied in an excitation path from a force lead terminal selected from the pacing leads. A measure lead is selected from among the other of the pacing leads and defibrillation leads, and the voltage induced in the lead under test is measured through the measure lead and the electrode/tissue interface of the measure lead and the defibrillation lead under test. The applied current in the excitation path is also measured, and an impedance value is derived from the measured current and voltage values. The test is continued with other selections of excitation and measure paths. Comparisons of the measured impedances with maximum and minimum impedance values are used to determine lead integrity failures. The lead impedance between two defibrillation leads is determined as a function of the sum of the derived defibrillation lead impedances.

Cardioversion/defibrillation lead impedance measurement system

An apparatus conducts current through a two terminal inductive load. The apparatus has a first conduction path, from a first supply voltage to one terminal of the inductive load and a second conduction path from the second terminal of the inductive load to a second supply voltage. The first conduction path includes a switching device that is controlled by a field-effect transistor having a gate terminal, second terminal, and third terminal. The gate terminal of the field-effect transistor is coupled to a reference voltage. The voltage at the second terminal of the field-effect transistor increases when the voltage at the field-effect transistor's third terminal increases.

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Lakeville, MN, United States of America

Robert John Schuelke