This work presents the design and simulation of an ultra-low-power voltage-controlled oscillator (VCO) for MICS (Medical Implant Communication Service) band applications. The VCO is based on a single ended CMOS inverter ring oscillator. For the voltage control, current starving has been employed. Current for the oscillator is provided by a beta multiplier reference (BMR) which is highly insensitive to supply noise. A digital current control is also implemented in this BMR to make the oscillator tunable over a wide range of 400 MHz to 935 MHz. Besides these, the oscillator circuit has an additional control for binary frequency shift keying. The oscillator along with the reference circuit consumes only about 2 µW with 1 V supply at 400 MHz frequency which is very suitable for low-power biomedical applications.
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