A Bluetooth Low Energy DCO in 28nm FDSOI

A 2.4 GHz digital-controlled oscillator (DCO) based on a novel capacitor tank suitable for all-digital Bluetooth Low Energy (BLE) transmitter is proposed in this paper. The capacitive element which is responsible for Gaussian Frequency Shift Keying (GFSK) modulation is constructed by a single nMOS device with simple topology, designed in a fully depleted silicon on insulator (FDSOI) process. The proposed capacitive element can offer capacitance difference in the range of a few aF with constant step. Consequently, it can provide accurate linear changes in frequency of a few KHz as required by the standard. The DCO circuit has been designed and simulated on a 2S nm FDSOI CMOS process, operating with 1V supply voltage and dissipating 1.5 mA. The phase noise is around -113 dBc at 1 MHz.