全數位式鎖相迴路之設計與實作

Abstract

ABSTRACT In this Thesis, we have presented the design of an all-digital phase-locked loop (ADPLL), which consists of a digitally controlled oscillator (DCO), a phase frequency detector (PFD), a control unit and some auxiliary logic circuits. A 16-bit digitally controlled CMOS oscillator uses a 4-stage ring of a modified differential delay cell. The DCO uses the even-stage skew dual-delay path scheme [11], which enables higher operating frequency. The frequency search and the phase tracking are major blocks in a control unit. We use a high sensitivity phase tracking and frequency search algorithm, which consists two D-type flip flop and some logical circuits. In our proposed ADPLL, we implement the DCO by full custom design style while the other circuits are implemented by cell-based design style. In order to rapidly evaluate the structures and algorithms, we model the DCO in Verilog construct, and verify the ADPLL system by Verilog simulator. The ADPLL is designed in the TSMC 0.18μm 1P6M technology. The supply voltage is 1.8V. The simulation results show that when DCO operates at 2.4GHz, the phase error is smaller than 100ps. The system dead zone is smaller than 30ps, and the lock in time is smaller than 30 reference clock cycles (algorithm). The lock-in range is 2.07GHz to 2.56GHz. The power consumption is 106.1mW at 2.4GHz.