A 1-v supply voltage controlled oscillator for intraocular pressure measurement

A 1-V supply LC (Inductive-Capacitive) VCO (Voltage Controlled Oscillator) for intraocular pressure measurement is presented. The VCO is fabricated in standard 0.18-μm CMOS (Complementary Metal Oxide Semiconductor) technology and occupies an active area of 700×750 μm². Two varactors from the 0.18-μm process are used to emulate a MEMS (Micro Electro-Mechanical System) capacitive membrane response (pressure sensor). A response with very good linearity was achieved within a tuning range of 6%, which fits the MEMS pressure sensor variation range. The phase noise was -85 dBc/Hz at a 600-KHz offset from the carrier frequency at 500 MHz. The power consumption was 10 mW from a 1-V power supply.