Low power loss current digital-to-analog converter used in an implantable pulse generator
First Claim
1. An implantable stimulator device, comprising:
- a first electrode implantable adjacent to tissue to be stimulated; and
a first output current source or sink coupled to the first electrode, wherein the first output current source or sink comprises a first transistor in a first output stage for passing an output current along a first output path to the first electrode, wherein the drain-to-source voltage drop across the first transistor is less than a drain-to-source voltage drop of the first transistor when operating in a saturation mode.
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Accused Products
Abstract
In one embodiment, the present invention provides an implantable stimulation device that includes output current sources and/or sinks configured to provide an output current for a load (i.e., tissue). The output path of the output current source or sink comprises a transistor which operates in a linear mode instead of a saturation mode. Because operation in a linear mode results in smaller drain-to-source voltage drops, power consumption in the output current source or sink (and hence in the implantable stimulator) is reduced, reducing battery or other power source requirements. Operation in the linear mode is facilitated in useful embodiments by a load in an input path (into which a reference current is sent) and a load in the output path (which bears the output current). The loads can be active transistors or passive resistors. A feedback circuit (e.g., an operational amplifier) receives voltages that build up across these loads, and sends a control signal to the gate of the transistor to ensure its linear operation.
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Citations
27 Claims
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1. An implantable stimulator device, comprising:
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a first electrode implantable adjacent to tissue to be stimulated; and
a first output current source or sink coupled to the first electrode, wherein the first output current source or sink comprises a first transistor in a first output stage for passing an output current along a first output path to the first electrode, wherein the drain-to-source voltage drop across the first transistor is less than a drain-to-source voltage drop of the first transistor when operating in a saturation mode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. At least one output current source or sink for an implantable stimulator device, comprising:
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a first input path for receiving a reference current;
a first output path for providing an output current to a first electrode of the implantable stimulator device, wherein the first electrode is implantable adjacent to tissue to be stimulated, and wherein a magnitude of the output current is dictated by a magnitude of the reference current; and
a first feedback circuit for comparing a first voltage on the first input path and a second voltage on the first output path, wherein the first feedback circuit controls a first transistor in the first output path such that the first transistor operates in a linear mode and not in a saturation mode. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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19. At least one output current source or sink for an implantable stimulator device, comprising:
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a first input path comprising a first load coupled to a power supply for receiving a reference current;
a first output path comprising a second load coupled to the power supply and a transistor, wherein the first output path comprises an output current coupled to a first electrode of the implantable stimulator device, wherein the first electrode is implantable adjacent to tissue to be stimulated; and
a first feedback circuit for comparing a first voltage on the first input path and a second voltage on the first output path, wherein the first feedback circuit controls the transistor such that the transistor operates in a linear mode and not in a saturation mode. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27)
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Specification