| الوصف: |
Sub-harmonic injection-locked technique has become popular to suppress the phase noise and to improve the jitter performance of ring oscillators in inductor-less PLLs [1]. However, conventional injection-locked PLLs (IL-PLLs) require a frequency divider chain for frequency selection and thus suffer from frequency misalignment and imperfection injection timing, which results in jitter degradation and even locking failure [2]. To solve this problem, a dedicated delay cell is used for frequency alignment [3] at a cost of extra power and chip area. Frequency misalignment is calibrated using the quadrature VCO in [4], but its performance is limited by the quadrature error and power consumption. |