A 160-?W, ring digitally controlled oscillator for UHF/VHF nano-satellites broadcasting tuners in 90nm CMOS process

This paper presents a two-stages 5bit digitally controlled oscillator designed mainly for Nano-Satellites (Amateur) applications. The structure based on a ring oscillator and implemented with Schmitt trigger inverters (Hysteresis Delay Cell) to lead the low frequencies, which has power and area efficiency better as compared with conventional delay cells. The proposed DCO offers the possibility to adjust the oscillation frequency digitally, without analog voltage tuning. Simulations of the proposed DCO achieve controllable frequency range of 118MHz~462MHz with a wide linearity. Monte Carlo simulation demonstrates that the deviation offset frequency due to random process fluctuation is fewer than 7.4%. Phase noise at 436.5MHz carrier frequency and 1MHz offset is -100dBc/Hz. Figure of Merit (FoM) calculated is -174.78dBc/Hz. In 90nm CMOS technology, the circuit occupies an area of 0.0084mm2 and least significant bit (LSB) resolution of 5 kHz. With a supply voltage of 1.0V, the estimated average power values are 104 and 158μW at 145 and 436.5MHz, respectively.