Programmable band-pass amplifier for use with implantable medical device
First Claim
1. A programmable implantable medical device comprising:
- a pacemaker for generating stimulation pulses;
a pair of electrodes coupled to the pacemaker for sensing electrical signals developed therebetween and for delivering said stimulation pulses to a desired location;
programmable band-pass amplifier means coupled to said electrodes for sensing and processing electrical signals, said programmable band-pass amplifier means including;
an amplifier having an input terminal and an output terminal, said electrical signals sensed by said electrodes being applied to said input terminal, said amplifier causing said electrical signals to be amplified by a desired gain factor and presented at the output terminal of said amplifier,capacitor means for coupling to the amplifier,switching means for switchably coupling said capacitor means to said amplifier, said switching means limiting the electrical signals amplified by said gain factor to those electrical signals having a frequency that falls within a band of frequencies bounded by a lower cut-off frequency and an upper cut-off frequency, the upper and lower cut-off frequencies of said frequency band being controlled by the rate at which said capacitor means is switchably coupled to said amplifier by said switching means, said switching rate, in turn, being controlled by a clock signal applied to said switching means; and
clock signal generating means coupled to said switching means for generating said clock signal at one of a plurality of possible clock frequencies, said clock signal generating means responsive to a remotely telemetered signal for selecting one of the plurality of possible clock frequencies for controlling the rate at which said capacitor means is switchably coupled to said amplifier;
whereby the frequency band of said band-pass amplifier means can be changed to a desired value by remotely changing the frequency of the clock signal generated by said clock signal generating means.
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Accused Products
Abstract
A switched-capacitor, band-pass, programmable amplifier is used as a sense amplifier in an implantable cardiac pacemaker. Switching means are used to switchably connect various capacitors to the same amplifier circuits. Clock generator means are used to generate clock signals that are used to control the rate at which the switching means operates. By programmably selecting the switching rate to be a desired value, the band-pass characteristics and gain of the sense amplifier may be varied. When a pacemaker stimulation pulse occurs, the band-pass characteristics and/or gain of the sense amplifier, may also be automatically varied to improve amplifier recovery time. The rate at which the capacitors are switchably connected to the amplifier circuits, may be selected remotely, thereby allowing the band-pass characteristics to be programmable.
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Citations
14 Claims
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1. A programmable implantable medical device comprising:
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a pacemaker for generating stimulation pulses; a pair of electrodes coupled to the pacemaker for sensing electrical signals developed therebetween and for delivering said stimulation pulses to a desired location; programmable band-pass amplifier means coupled to said electrodes for sensing and processing electrical signals, said programmable band-pass amplifier means including; an amplifier having an input terminal and an output terminal, said electrical signals sensed by said electrodes being applied to said input terminal, said amplifier causing said electrical signals to be amplified by a desired gain factor and presented at the output terminal of said amplifier, capacitor means for coupling to the amplifier, switching means for switchably coupling said capacitor means to said amplifier, said switching means limiting the electrical signals amplified by said gain factor to those electrical signals having a frequency that falls within a band of frequencies bounded by a lower cut-off frequency and an upper cut-off frequency, the upper and lower cut-off frequencies of said frequency band being controlled by the rate at which said capacitor means is switchably coupled to said amplifier by said switching means, said switching rate, in turn, being controlled by a clock signal applied to said switching means; and clock signal generating means coupled to said switching means for generating said clock signal at one of a plurality of possible clock frequencies, said clock signal generating means responsive to a remotely telemetered signal for selecting one of the plurality of possible clock frequencies for controlling the rate at which said capacitor means is switchably coupled to said amplifier; whereby the frequency band of said band-pass amplifier means can be changed to a desired value by remotely changing the frequency of the clock signal generated by said clock signal generating means. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A sensing amplifier for use in an implantable medical device, said implantable medical device generating prescribed event signals and including a pair of electrodes between which said prescribed event signals are carried and between which an electrical signal having a broad frequency spectrum may be developed, said sensing amplifier comprising:
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means for coupling the pair of electrodes to the sensing amplifier; a first capacitor; first amplifier means coupled to said pair of electrodes for amplifying selected frequency components of the electrical signal developed between said pair of electrodes, said selected frequency components comprising those components of said electrical signal having a frequency less than a first specified frequency, said first specified frequency being determined by the rate at which said firsts capacitor is switchably connected to said first amplifier means; clock generating means for generating first and second clock signals; first switching means responsive to said first clock signal for switchably connecting said first capacitor to said first amplifier means at a first switching rate derived from said first clock signal, whereby said first clock signal comprises a first control parameter that defines said first specified frequency; a second capacitor; second amplifier means coupled to said pair of electrodes, said selected frequency components comprising those components of said electrical signal having a frequency greater than a second specified frequency, said second specified frequency being determined by the rate at which said second capacitor is switchably connected to said second amplifier means; second switching means responsive to said second clock signal for switchably connecting said second capacitor to said second amplifier means at a second switching rate derived from said second clock signal, whereby said second clock signal comprises a second control parameter that defines said second specified frequency; and means for serially connecting said first and second amplifier means, whereby only those frequency components of the electrical signal developed between said pair of electrodes above said second specified frequency and below said first specified frequency are amplified by the serial combination of said first and second amplifier. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A programmable implantable medical device comprising:
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a pair of electrodes for sensing signals developed therebetween and delivering simulation pulses generated by said implantable medical device; amplifier means coupled to said electrodes for sensing and processing said developed signals, said amplifier means comprising; a plurality of capacitors, a first amplifier circuit, first switching means responsive to a first select signal for connecting desired combinations of said plurality of capacitors to said first amplifier circuit, second switching means responsive to a clock signal for connecting at least one of said plurality of capacitors to said first amplifier circuit at a frequency determined by said clock signal, and said first amplifier circuit having a gain factor that is controlled by the particular combination of capacitors that are connected thereto by said first switching means, and a band-pass characteristic that is a function of the frequency at which said second switching means connects and disconnects said at least one of said plurality of capacitors thereto; clock signal generating means for generating said clock signal at a frequency determined by a second select signal; and telemetry means for receiving a remotely telemetered command signal and for selectively generating said first and second select signals in response to a received remotely telemetered command signal, whereby the gain and band-pass characteristics of said amplifier within said implantable medical device can be remotely selected. - View Dependent Claims (14)
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Specification