Patent ID: 8515545

Claim:
A medical device, comprising: a neurostimulator that includes one or more channels, wherein each channel includes: a digitally-controlled switch coupled to a voltage source, wherein the switch is in one of: an “on” state and an “off” state in response to a first control signal; a digitally-controlled current sink coupled to the switch in a manner such that the switch is coupled between the current sink and the voltage source, wherein the current sink is electrically isolated from the voltage source when the switch is in the “off” state, and wherein the current sink draws a variable amount of electrical current in response to a second control signal, and wherein the second control signal includes a plurality of bits, and wherein the current sink includes a plurality of first transistors and a plurality of second transistors, wherein the first transistors are each coupled to the switch through a respective one of the second transistors, wherein the first transistors are each operable to draw a current that is an integer multiple of a reference current, and wherein the second transistors are operable to be individually turned on or off by a corresponding bit of the second control signal, thereby enabling the respectively-coupled first transistor to draw current or preventing such first transistor from drawing current; and a conductor coupled to the switch and the current sink, wherein the conductor is configured to be coupled to an electrode that is operable to deliver the electrical current drawn by the current sink to a target tissue area.