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

This paper presents the design of an 800 MHz VCO for both free-running and injection locked operation in a novel low power transmitter with wireless frequency reference, operating in the MICS band (402-405 MHz). The transmitter employs simultaneous tuning and locking, to set the desired channel with a minimal injected power. The VCO is designed and fabricated in a 0.13 $\mu \mathrm{m}$ SiGe BiCMOS process and has a core area of 0.5 $\mathrm{m}\mathrm{m}^{2}$. The measurement of the free-running VCO shows -107 dBc/Hz phase noise at 300 kHz frequency offset. If locked to an external frequency reference the VCO shows 118 dBc/Hz phase noise at 300 KHz offset, while consuming 3 mA from a 1.2 V supply (3.6 mW). When the VCO is tuned during the locking, 20 dBm of reference power is required to enable operation in the whole MICS band. The measured phase noise of the free-running VCO ensures reliable calibration of the proposed transmitter and the locked VCO satisfies all requirements of an implantable device using MICS band data transmission. Therefore, this VCO presents a key building block of an injection locked, frequency agile, implantable transmitter for the MICS band.