Voltage/current control system for a human tissue stimulator

An implanted human tissue stimulator comprising:

• receiver means for receiving a data signal from an external transmitter, the data signal comprising a series of data frames containing an end of frame signal, each data frame comprising a plurality of data words, each data word defining an amplitude for a tissue stimulating signal for a different output channel of the tissue stimulator, and a command word for controlling a processor means in the tissue stimulator;
• power supply means coupled to said receiver means for extracting a raw power signal from the data signal and generating at least one power supply voltage from the raw power signal and distributing the at least one power supply voltage throughout the human tissue stimulator to provide operating power for the human tissue stimulator;
• a plurality of output channels, each having a tissue stimulating electrode connected thereto;
• and
• processor means for serially processing the plurality of data words and command word in each data frame received by the receiver means, said processor means comprising
• a command detector means responsive to the command words received by said receiver means for controlling the functions of the processor means,
• data word latching means for successively storing the data words received in a data frame by said receiver means, and
• switch means for successively coupling amplitude voltages representative of output signals from the data word latching means to successive ones of the output channels;
• and wherein
• each of the plurality of output channels includes:
• refresh voltage controller means for generating an isolated refresh voltage for the output channel, said refresh voltage controller means including at least one flying capacitor and means for alternately connecting the at least one flying capacitor to receive the at least one power supply voltage from the power supply means and then disconnecting the at least one flying capacitor from the power supply means to provide the isolated refresh voltage for the output channel, and
• a voltage controlled current source powered by the isolated refresh voltage provided by the refresh voltage controller means for amplitude controlling, in accordance with the amplitude voltages coupled from the switch means, tissue stimulating signals to the stimulating electrode of the output channel.