用于高精度图像传感器的锁相环

为了提高图像传感器的探测精度,给像素中的传输管提供高精度时钟信号,设计了一款可编程式电荷泵锁相环(Phase-Locked Loop,PLL)模块。该模块使用分频器以输出可调控频率的时钟,增加了复用性;在电荷泵中加入单位增益放大器以消除毛刺,增大了锁相环精度;同时给出了针对整个模块的相位噪声分析。仿真结果表明,当输出200 MHz时钟时,信号的时钟抖动为28 ps,电路工作在1.5 V电压下的功耗<2 mW。该模块已用于一款高精度图像传感器中,在0.11μm CMOS工艺下进行了流片,测试结果表明其可以实现50 MHz到200 MHz的高精度时钟输出,满足了芯片对于时钟的需求。

A Phase-Locked Loop for High-Precision Image Sensors

In order to increase the detection accuracy image sensor and provide high-precision clock signal to the transmission tube in the pixel,a programmable charge pump phase-locked loop(PLL)module is designed.The module uses a frequency divider to output a clock with adjustable frequency,which increases reusability.A unity gain amplifier is added to the charge pump to eliminate glitch and increase the accuracy of the phase-locked loop.The analysis of phase noise is given for the entire module.The simulation results show that when the module outputs 200 MHz clock,the clock jitter of the signal is 28ps.The power consumption of the circuit operates at 1.5 V<2 mW.And the module has been used in a high-precision image sensor,and the flow is performed in 0.11μm CMOS process.The test results show that it can achieve high-precision clock output from 50 MHz to 200 MHz,which satisfies the chip’s demand for clock.