Analysis and design of two-stage ring oscillators with dual-input injection at millimeter waves

摘要

In this paper, a new analytic approach is proposed for injection-locked ring oscillators (ILROs) design at millimeter waves (mm-waves). Using time and transfer constants (TC) analysis, a two-pole model of the delay stage is applied into the injection-locking behavior model for an N-stage ring oscillator, and analytic expressions of the self-resonance frequency (SOF) and the locking range are derived. These expressions are concise and based solely on device-level circuit parameters, enabling fast and exact ILRO design through DC and AC simulations. In addition, a dual-input injection technique is investigated and a layout optimization technique is presented. Using a 0.13-mu m SiGe BiCMOS process, a two-stage ring oscillator with dual-input injection is implemented for verification. The fabricated divider achieves a wide locking range from 16 to 67 GHz at -10-dBm input power. The divider core consumes a current of 3.9 mA from 3.3 V supply with an area of 45 x 60 mu m(2). The measured results agree well with theoretical analyses and simulated results.