Self-timed rings as low-phase noise programmable oscillators

Laurent Fesquet (1) , Abdelkarim Cherkaoui (2) , Oussama Elissati (3)

1 TIMA - Techniques de l'Informatique et de la Microélectronique pour l'Architecture des systèmes intégrés
2 LHC - Laboratoire Hubert Curien
3 STRS Laboratory

Self-timed rings are promising for designing highspeed serial links and system clock generators. Indeed, their architecture is well-suited to digitally control their frequency and to easily adapt their phase noise by design. Self-timed ring oscillation frequency does not only depend on the number of stages as the usual inverter ring oscillators but also on their initial state. This feature is extremely important to make them programmable. Moreover, with such ring oscillators, it is easy to control the phase noise by design. Indeed, 3dB phase noise reduction is obtained at the cost of higher power consumption when the number of stages is doubled while keeping the same oscillation frequency, thanks to the oscillator programmability. In this paper, we completely describe the method to design selftimed rings in order to make them programmable and to generate a phase noise in accordance with the specifications. Test chips have been designed and fabricated in AMS 0.35 μm and in STMicroelectonics CMOS 65 nm technology to verify our models and theoretical claims.

Keywords: self-timed ring; oscillator; true random number generator

Domains: Computer Science [cs]; Embedded Systems; Computer Science [cs]; Cryptography and Security [cs.CR]

Laurent Fesquet, Abdelkarim Cherkaoui, Oussama Elissati. Self-timed rings as low-phase noise programmable oscillators. The 12th IEEE International New Circuits and Systems Conference (NEWCAS 2014), Jun 2014, Trois-Rivières, Canada. 4 p. ⟨ujm-01011287⟩