A 2.5 GHz 8-phase phase-locked loop (PLL) is proposed for 10-Gbps system on chip (SoC) transmission links application. The proposed PLL has several features which use new design techniques. The first one is a new variable delay cell (VDC) for the voltage control oscillator (VCO). Its advantages over the conventional delay cell are: wide-range output frequency and low noise sensitivity with low KVCO. The second feature is that, the PLL consists of a self-calibration circuit (SCC) which protects the PLL from variations in the process, voltage and temperature (PVT). The third feature is that, the proposed PLL has an 8-phase output frequency and also for avoiding the power/ground (P/G) effect and the substrate noise effect on the PLL, it also has a low jitter output frequency. The PLL is implemented in 0.13-µm CMOS technology. The PLL output jitter is 2.83 ps (rms) less than 0.7% of the output period. The total power dissipation is 21 mW at 2.5 GHz output frequency, and the core area is 0.08 mm2.

In this paper, an efficient bottom-up extraction approach is presented to generate accurate behavioral models of PLL designs more quickly by using Verilog-AMS language. The main idea is to use a special "characterization mode" such that we can use only one input pattern to get all required circuit parameters with parasitic effects. After carefully adjustment, all parameters in our behavioral models can be measured at the outputs of the PLL system without simulating each block separately. Therefore, this approach is more suitable to accurately model protected IPs or flattened post-layout netlists. In the experimental results, we will build an accurate PLL behavioral model for demonstration and compare the results with HSPICE simulation and traditional behavioral models.