Low energy communications for implanted medical devices

An implanted medical device that is adapted to deliver therapy to a nerve or muscle tissue of a patient and also configured for radio frequency communication with an external unit or units, the implanted medical device comprising:

• a low frequency quartz oscillator circuit configured to generate a low frequency clock signal;
• a sleep timer circuit that is adapted for operation with the low frequency clock signal and configured to periodically activate the implanted medical device from a sleep mode to an active mode;
• an on chip silicon MEMS resonator circuit that is configured to selectively generate an oscillator signal when the implanted medical device is operated in the active mode, wherein oscillator signal has a reference frequency corresponds to a characteristic resonant frequency of the MEMS resonator;
• and
• frequency compensation means selectively operated with the oscillator signal from the MEMS oscillator circuit when the implanted medical device is operated in the active mode, wherein the frequency compensation means provides carrier frequency control and/or precision timing for the radio frequency communications using the measured frequency error of the reference frequency relative to the low frequency clock signal from the low frequency quartz oscillator circuit, and also using a frequency compensation factor without frequency adjustment of the oscillator signal.