A fast start-up 3GHz–10GHz digitally controlled oscillator for UWB impulse radio in 90nm CMOS

A digitally controlled ring oscillator, key component of a UWB transceiver, is presented. The design supports the IEEE 802.15.4a standard for which all bands between 3 and 10GHz can be synthesized with frequency steps as small as 4MHz. It is to be embedded in a low power fast startup phase-aligned frequency-locked loop requiring a duty-cycled operation of the DCO with a settling time below 2ns. The average power consumption ranges from 0.3mW at 3GHz up to 1mW at 10GHz in 90nm 1V digital CMOS.