A Low Power Low Phase Noise Oscillator for MICS Transceivers

Area of Science:

• Electrical Engineering
• Biomedical Engineering
• Integrated Circuit Design

Background:

• Medical Implantable Communications Service (MICS) transceivers require low-power, high-performance oscillators.
• Existing oscillators face challenges with supply voltage and ground noise, impacting stability and phase noise.

Purpose of the Study:

• To develop a low-power, low-phase-noise quadrature oscillator specifically for MICS transceivers.
• To improve oscillator stability and reduce sensitivity to power supply disturbances.

Main Methods:

• A differential pair with positive feedback forms the core oscillator structure.
• A self-bias circuit is introduced to track and isolate supply voltage and ground disturbances.
• The circuit is fabricated using a 0.18 μm CMOS process.

Main Results:

• The oscillator generates 349–689 MHz I/Q signals within the MICS band.
• Measured phase noise is -108.45 dBc/Hz at a 1 MHz offset.
• Achieved low power consumption of 0.46 mW at 1.8 V supply and operates down to 1.2 V.

Conclusions:

• The proposed quadrature oscillator effectively addresses MICS transceiver requirements for low power and low phase noise.
• The self-bias circuit significantly enhances noise immunity and operational stability.
• The compact design and low power consumption make it suitable for implantable devices.