| Title |
A Study on the Optimum Design of Charge Pump PLL with Dual Phase Frequency Detectors |
| Authors |
우영신(Woo, Young-Shin) ; 장영민(Jang, Young-Min) ; 성만영(Sung, Man-Young) |
| Keywords |
Dual PFDs ; Fast Acquisition ; High Frequency ; Low Jitter |
| Abstract |
In this paper, we introduce a charge pump phase-locked loop (PLL) architecture which employs a precharge phase frequency detector (PFD) and a sequential PFD to achieve a high frequency operation and a fast acquisition. Operation frequency is increased by using the precharge PFD when the phase difference is within -π~π and acquisition time is shortened by using the sequential PFD and the increased charge pump current when the phase difference is larger than pmπ. So error detection range of the proposed PLL structure is not limited to -π~π and a high frequency operation and a higher speed lock-up time can be achieved. The proposed PLL was designed using 1.5 μm CMOS technology with 5V supply voltage to verify the lock in process. The proposed PLL shows successful acquisition for 200 MHz input frequency. On the other hand, the conventional PLL with the sequential PFD cannot operate at up to 160MHz. Moreover, the lock-up time is drastically reduced from 7.0 μs to 2.0 μs only if the loop bandwidth to input frequency ratio is regulated by the divide-by-4 counter during the acquisition process. By virtue of this dual PFDs, the proposed PLL structure can improve the trade-off between acquisition behavior and locked behavior. |