360nW self-calibrated clock generator operating from −50°C to 120°C

An ultra-low power, self-calibrated clock generator for UHF RFID transponder is presented and fabricated. The frequency can be calibrated automatically by applying successive approximation technique. Frequency variation is less than ±4% of nominal 320 kHz with a rather wide supply voltage range from 0.7V to 1.6V and temperature range from −50°C to 120°C. The whole circuit consumes only 360nW at 0.7V and takes up 130µm × 90µm in 0.18µm CMOS mixed-signal process.