Abstract: An apparatus and corresponding method for providing data communications to and from a location within a body cavity in which an internal transmitter receives a first data stream from an in vivo sensor, electrode, or transducer. The internal transmitter is configured and arranged to asynchronously modulate the first data stream and to provide as an output a first optical signal carrying the asynchronously modulated first data stream. The apparatus further includes an external receiver that is configured and arranged external to the body cavity such that an optical input to the external receiver is optically coupled to the internal transmitter output and receives the optical signal therefrom. The external receiver asynchronously demodulates the received optical signal and provides as an output at least one signal indicative of the first data stream.

Abstract: A precision current source is disclosed that includes a voltage setting circuit that precisely sets the voltage across a range setting resistor to set the current flowing in a load resistance connected in series with the range setting resistor. The voltage setting circuit precisely sets the voltage across the range setting resistor as a function of an input reference voltage. The voltage setting circuit includes an instrumentation amplifier that determines the voltage across the range setting resistor and the difference between this voltage and the reference voltage is used drive a drive voltage amplifier. The drive voltage amplifier output adjusts to minimize the difference between the reference voltage and the voltage across the range setting resistor. Other embodiments include the use of a DC blocking capacitor to allow only AC coupling and various nulling. circuits to remove any charge buildup on a DC blocking capacitor.

Abstract: A precision current source is disclosed that includes a voltage setting circuit that precisely sets the voltage across a range setting resistor to set the current flowing in a load resistance connected in series with the range setting resistor. The voltage setting circuit precisely sets the voltage across the range setting resistor as a function of an input reference voltage. The voltage setting circuit includes an instrumentation amplifier that determines the voltage across the range setting resistor and the difference between this voltage and the reference voltage is used drive a drive voltage amplifier. The drive voltage amplifier output adjusts to minimize the difference between the reference voltage and the voltage across the range setting resistor. Other embodiments include the use of a DC blocking capacitor to allow only AC coupling and various nulling circuits to remove any charge buildup on a DC blocking capacitor.

Abstract: An apparatus and corresponding method for providing data communications to and from a location within a body cavity in which an internal transmitter receives a first data stream from an in vivo sensor, electrode, or transducer. The internal transmitter is configured and arranged to asynchronously modulate the first data stream and to provide as an output a first optical signal carrying the asynchronously modulated first data stream. The apparatus further includes an external receiver that is configured and arranged external to the body cavity such that an optical input to the external receiver is optically coupled to the internal transmitter output and receives the optical signal therefrom. The external receiver asynchronously demodulates the received optical signal and provides as an output at least one signal indicative of the first data stream.