A Low-Power Injection-Locked VCO for an Implantable MICS Band Transmitter with Wireless Frequency Reference and...

Area of Science:

• Electrical Engineering
• Biomedical Engineering
• Integrated Circuit Design

Background:

• Implantable medical devices require low-power, reliable wireless communication systems.
• The Medical Implant Communication Service (MICS) band (402-405 MHz) is allocated for short-range medical telemetry.
• Frequency agility and low phase noise are critical for efficient and robust data transmission in implantable transmitters.

Purpose of the Study:

• To design and characterize an 800 MHz voltage-controlled oscillator (VCO) for a novel low-power transmitter.
• To evaluate the VCO's performance in both free-running and injection-locked modes for MICS band applications.
• To demonstrate the VCO as a key building block for frequency-agile, implantable transmitters.

Main Methods:

• The voltage-controlled oscillator (VCO) was designed and fabricated using a 0.13 μm SiGe BiCMOS process.
• Simultaneous tuning and locking techniques were employed for channel selection with minimal injected power.
• Performance was measured, including phase noise in free-running and injection-locked states, power consumption, and required reference power for tuning.

Main Results:

• The free-running VCO exhibited a phase noise of -107 dBc/Hz at a 300 kHz offset.
• The injection-locked VCO achieved a phase noise of -118 dBc/Hz at a 300 kHz offset, consuming only 3.6 mW.
• Operation across the entire MICS band was enabled with 20 dBm of reference power during locking.

Conclusions:

• The designed VCO meets the stringent phase noise requirements for reliable calibration and operation of MICS band transmitters.
• The injection-locked VCO performance satisfies the demands for implantable devices utilizing MICS band data transmission.
• This VCO is a crucial component for developing advanced, frequency-agile, implantable transmitters for medical applications.