Although an injection-locked oscillator (ILO) can offer excellent jitter performance on average, its intense phase modification at a given injection rate inevitably degrades spur performance, unless injection timing is carefully controlled. This work investigates a behavioral model of the ILO with digital control of a bang-bang phase detector (BBPD) on a discrete-time domain, a quantitative analysis on the dynamics of the digital injection-locked clock multiplier (ILCM) is provided. Adjusting frequency error between the free-running oscillator and the injection signal is crucial to obtain better spur performance. However, the timing offset caused by the device mismatches hinders it from being correctly compensated. Therefore, we investigate the effect of timing offset (or mismatch) between the replica cells and BBPD and then propose the time-division dual calibration (TDDC) to reduce the discrepancies. In addition, three-stage replica cells are chosen to achieve a robust operation in the phase generating aspect. By removing the residual phase offset using multiple delay cells, the optimum locking point is guaranteed.
Bibliographical noteFunding Information:
Manuscript received August 27, 2020; revised November 10, 2020, January 20, 2021, and February 22, 2021; accepted February 23, 2021. Date of publication March 25, 2021; date of current version July 23, 2021. This article was approved by Associate Editor Pietro Andreani. This work was supported by the IC Design Education Center (IDEC), Daejeon, South Korea. (Corresponding author: Deog-Kyoon Jeong.) Min-Seong Choo was with the Department of Electrical and Computer Engineering, Seoul National University, Seoul 08826, South Korea, and also with the Inter-University Semiconductor Research Center, Seoul National University, Seoul 08826, South Korea. He is now with the Department of Electrical Engineering, Columbia University, New York, NY 10027 USA (e-mail: firstname.lastname@example.org; email@example.com).
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All Science Journal Classification (ASJC) codes
- Electrical and Electronic Engineering