A 2-to-20 GHz Multi-Phase Clock Generator with Phase Interpolators Using Injection-Locked Oscillation Buffers for High-Speed IOs in 16nm FinFET

Abstract

To support high-speed IOs, a 2-to-20 GHz cross-coupled inverter-based multi-phase PLL with phase interpolators using injection-locked oscillation buffers is presented. The proposed voltage-controlled oscillator (VCO) is made of two 4-stage ring oscillators (RO), where the introduction of feedback and cross-coupled resistances enable the VCO to run at higher speeds compared to a conventional 4-stage RO. Injection-locked oscillation buffering is proposed to restore swing and reduce duty-cycle error (DCE) for VCO output buffers and PIs. Fabricated in 16nm process, it runs 25% faster and consumes 20% less power than prior works, with less than 1.8% DCE at 20 GHz across PI code range.