A Low-Complexity, Low-Phase-Noise, Low-Voltage Phase-Aligned Ring Oscillator in 90 nm Digital CMOS

An 8-phase phase-aligned ring oscillator in 90 nm digital CMOS is presented that operates up to 2 GHz. The low-complexity circuit consumes 13 mW at 2 GHz and 1.2 mW at 400 MHz, while a flat in-band phase noise below $-$120 dBc$/$Hz is achieved, in close agreement with the presented theory. The circuit occupies an area of 0.008 mm$^{2}$ .