US 5,964,787 A · Stimulus system with controllable switched capacitor output stage

Abstract

There is provided an output stage for a battery powered implantable device, such as a cardiac pacemaker, for generating biphasic or triphasic pulses, each pulse having at least a prestimulus or poststimulus pulse of a first polarity, and a stimulus pulse of opposite polarity. The output stage provides for charging of a small sized pacing capacitor from the battery through a high rate charge pump only during delivery of a prestim or poststim pulse, and for discharging the pacing capacitor during the stimulus portion of the overall pulse. A fast or high rate capacitive charge pump is used with a controllable high rate clock signal, adjustment of the clock signal being used for controlling the charging rate during the prestim or poststim pulses, thereby allowing for tuning of the parameters of the prestim or poststim pulse portions. The charge pump is enabled only during such charging pulse durations, thereby eliminating the need for a large holding capacitor, and enabling an output stage with a significantly reduced capacitor requirement.

Claims22

Dependent claims

An output stage circuit for receiving power from a DC voltage source, and for delivering output pulses to a load, comprising:

a fast capacitive charge pump, having an input connected to said voltage source, switchable capacitive pump means for providing an amplified voltage, first switch means for switching said capacitive pump means at a controllable high switching rate, and a pump output for providing said amplified voltage;
a pace capacitance connected to said pump output and to said load;
second switching means for switching said pace capacitance into a first electrical circuit for a first predetermined duration, whereby it discharges through said load to provide a first polarity pulse to said load;
and into a second circuit for a second predetermined duration, whereby it charges from said voltage source and said charge pump through said load to provide a second polarity pulse of duration D to said load,
pump activation means for activating said charge pump to provide an output substantially only when said pace capacitance is switched into said second circuit during duration D;
and
said first switch means has rate means for setting said high switching rate much greater than 1/D Hz.

4 more elements

A cardiac pacemaker for generating pacing pulses, comprising:

a battery source of power, providing a voltage output of Vb;
output terminals, for connection to a pacing lead for delivery of pacing pulses to an electrical load in the form of a patient's heart;
output capacitive means connected to one of said terminals, for capacitively coupling said pacing pulses to said heart load;
switching capacitance voltage pump means connected to receive power from said battery, for generating a voltage output of about nVb when enabled;
first pulse control means for enabling said pump means only during a said pacing pulse and for connecting said output capacitive means in a charging path with said pump means for a predetermined charging duration during a said pacing pulse, thereby delivering a charging pulse through said output terminals for said charging duration;
said first pulse control means comprising clock means for clocking said pump means at a high rate relative to said charging duration;
and
second pulse control means for connecting said output capacitive means in a discharging path with said heart for a predetermined discharging duration, thereby delivering a discharging pulse through said output terminals for said discharging duration.

5 more elements

Dependencies are inferred from the claim text.

Stimulus system with controllable switched capacitor output stage

Life of this patent

Stimulus system with controllable switched capacitor output stage

Life of this patent

Abstract

Claims22