Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical therapeutic systems
Reexamination Certificate
1999-04-16
2001-09-25
Bockelman, Mark (Department: 3737)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical therapeutic systems
C607S032000, C128S903000
Reexamination Certificate
active
06295473
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to communication receivers adapted for use with an implantable medical device. More particularly, the present invention pertains to a digital delay line receiver for receiving and demodulating data transmitted by an implantable medical device.
BACKGROUND OF THE INVENTION
Various implantable medical devices have been developed that receive information from one or more physiologic sensors or transducers. A typical physiologic sensor transduces a measurable parameter of the human body, such as blood pressure, temperature or oxygen saturation for example, into corresponding electrical signals. At the appropriate time, the physiologic data acquired by an implantable medical device is uplinked to an external receiving system, such as a programmer, for storage and analysis.
In many implantable medical device applications, a radio frequency (RF) telemetry technique is used by which data acquired by an implantable medical device is impressed on a carrier signal and transmitted to an external receiving system during a data uplink procedure. A demodulator is typically provided in the receiving system that recovers the physiologic information signal from a modulated signal received from the implantable medical device. In many receiving systems, differences between Q's (i.e., shape factor or quality factor) of the transmitting and receiving antennae result in corruption of the transferred signal in a non-controlled way, such as introduction of undesirable bit-to-bit amplitude variations.
Most conventional receiving systems employ an analog design or, alternatively, a mixed analog/digital design for the receiving system circuitry. As such, most conventional receiving systems are typically implemented using a “custom” design approach, which is both expensive and limited in terms of the potential to use standardized, readily available, and relatively inexpensive electronic components. Using analog components in a particular design is generally associated with increased power consumption, in contrast to a fully digital implementation. Increasing the power consumption requirements of the receiving system may pose a problem in portable and small scale applications.
A traditional receiving system implementation which utilizes an analog or mixed analog/digital design may also be relatively intolerant to frequency variations in the data transmitted by the implantable medical device. A more precise, and therefore more expensive, telemetry methodology employed in the implantable medical device is often required to address such frequency variation intolerance in conventional designs.
Various implementations of RF telemetry systems designed for use with an implantable medical device are known in the art, examples of which may be found in the issued U.S. Patents listed in Table 1 below.
TABLE 1
Patent No.
Inventor(s)
Issue Date
4,281,664
Duggan
August 4, 1981
4,494,545
Slocum et al.
January 22, 1985
4,556,063
Thompson et al.
December 3, 1985
4,562,840
Batina et al.
January 7, 1986
4,571,589
Slocum et al.
February 18, 1986
4,681,111
Silvian
July 21, 1987
4,757,816
Ryan et al.
July 19, 1988
4,949,299
Silvian
July 31, 1990
5,058,581
Silvian
October 22, 1991
5,107,833
Barsness
April 28, 1992
5,127,404
Wyborny et al.
July 7, 1992
5,241,961
Henry
September 7, 1993
5,264,843
Silvian
November 23, 1993
5,292,343
Blanchette et al.
March 8, 1994
5,300,093
Koestner et al.
April 5, 1994
5,312,453
Shelton et al.
May 17, 1994
5,383,912
Cox et al.
January 24, 1995
5,475,307
Silvian
December 12, 1995
5,620,472
Rahbar
April 15, 1997
The patents listed in Table 1 hereinabove are hereby incorporated by reference herein in their respective entireties. As those of ordinary skill in the art will appreciate readily upon reading the Summary of the Invention, the Detailed Description of Various Embodiments, and the claims set forth below, many of the devices and methods disclosed in the patents identified below and listed in Table 1 above may be modified advantageously by using the teachings of the present invention.
SUMMARY OF THE INVENTION
The present invention has certain objects. That is, various embodiments of the present invention provide solutions to one or more problems existing in the prior art with respect to telemetry receiving systems for use with implantable medical devices. Such problems associated with prior art receiving systems include, for example, a relative intolerance to frequency variations in the data transmitted by the implantable medical device, reduced signal-to-noise ratios in certain circumstances, inability to utilize standardized, low-cost, and readily available electronic components, and relatively complex analog or mixed analog/digital circuit implementations.
Various embodiments of the present invention have the object of solving at least one of the foregoing problems. While some systems have been able to solve the general problem of receiving and demodulating data produced by an implantable medical device, such approaches have generally resulted in implementations that increase noise, reduce frequency variation tolerances in the data transmitted by the implantable medical device, increase design and integration complexity, and increase the power consumed by the circuitry of the receiving system. It is therefore another object of the present invention to provide an improved apparatus and methodology for receiving and demodulating RF data transmitted by an implantable medical device that fulfills at least one of the foregoing objects.
In comparison to known implementations of receiving system circuitry, various embodiments of the present invention may provide one or more of the following advantages: eliminating amplitude variations in the data transmitted by an implantable medical device due to transmitting and receiving antennae mismatch; increasing the frequency variation tolerance of the receiving system circuitry; eliminating all analog elements in the demodulator circuit; providing the opportunity to utilize standardized, low-cost, digital components in the receiving/demodulation circuit design; and reducing the power and circuit board/chip space required to support the receiving/demodulation circuitry.
Some embodiments of the invention include one or more of the following features: a receiver that receives and digitally demodulates a modulated analog signal received from a body implantable medical apparatus; an analog-to-digital converting circuit that produces an amplitude limited modulated digital signal corresponding to a modulated analog signal received from a body implantable medical apparatus; an analog-to-digital converting circuit of a relatively simple design which includes an amplifier coupled to a receive antenna, and a comparator having an input coupled to the amplifier and an output coupled to a digital demodulator; a digital demodulator that demodulates a modulated digital signal to produce a digital information signal, such as a signal containing physiologic sensor data; a digital demodulator that produces a digital information signal from the modulated digital signal by detecting coherent information between data bits of the modulated digital signal; a digital demodulator which includes a digital delay line comprising a plurality of shift registers; a digital demodulator which includes a digital delay line comprising a plurality of multiple-stage delay blocks each coupled to a tap selection device; a digital demodulator that comprises a digital delay line having an input coupled to an output of the converting circuit, an exclusive OR (XOR) gate having a first input coupled to an output of the digital delay line, and a conductor coupled between the input of the digital delay line and a second input of the XOR gate, such that a delayed modulated digital signal and a non-delayed modulated digital signal are applied to the first and second XOR gate inputs, respectively, so as to produce a digital information signal at an output of the XOR gate; a digital demodulator which is implemented in a Field-Programmable G
Bockelman Mark
Medtronic Inc.
Wolde-Michael Girma
LandOfFree
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