高精度低功耗唤醒时钟的设计与实现.pdf

摘要 摘要 无线传感网是物联网技术的典型代表。为节省功耗，传感网节点通常采用低占空比 的工作模式。在睡眠模式下，唤醒时钟的功耗是总功耗的主要部分；同时，为了减小唤 醒时间，时钟的准确性也至关重要。虽然32kHz 晶振电路时钟精度很高，但其功耗较高， 且不利于芯片的集成。本文设计了一种基于压控振荡器的高精度低功耗唤醒时钟电路。 本文从压控振荡器的设计和偏置电压产生电路两方面来实现高精度低功耗唤醒时 钟。针对低频、低电压的工作场景，本文采用压控振荡器电路设计，提出基于晶体管漏 电的差分输入延时结构，提高了振荡电路的抗干扰性能。针对偏置电压产生电路，本文 提出开关电阻、电容串联结构，通过开关电阻、电容的串联分压得到稳定的偏置电压。 其中开关电阻替代传统的电流基准电路，开关电容为运算放大器提供尾电流，降低了整 体电路功耗。采用温度系数相反的两种电阻补偿整体电路的温漂，使电路输出频率更加 稳定。设计可配置校准电容，通过配置电容不仅可以校准不同工艺偏差下的输出频率， 还可以微调因温度变化引起的频率变化，以提高电路输出频率的稳定性。 2 本文设计的高精度低功耗唤醒时钟电路采用GF130nm 工艺，面积为0.496mm 。后 仿真结果表明：温度在-30~90℃ 内时，振荡器的频率温漂为 45ppm/℃ ；供电电压在 0.7~ 1.3V 内时，频率变化为1.1%/V 。在TT-1V 的条件下，振荡器输出1kHz 的频率，功 耗为3.71nW 。该结果与已有的研究相比时钟精度提升8 倍~35 倍，相比目前精度最高的 设计，功耗降低36% 。 关键词：唤醒时钟，低功耗，压控振荡器，频率稳定性 I Abstract Abstract Wireless sensor network is a typical representative of Internet of Things. Heavily duty- cycled mode is adopted for sake of power saving, and the wakeup clock ’s power consumption in sleep mode is the main part of the total power consumption. In addition, the accuracy of the clock is very important for the communication between sensor nodes. Although the commonly used 32 kHz real-time clock has high accuracy, its power consumption is still high, and quartz crystal is not conducive to chip integration. Therefore, a wakeup clock circuit based on self- biased voltage-controlled oscillator (VCO) is proposed. The basic principle and implementation method of wake-up clock circuit is systematically elaborated. In view of the clock generation circuit, the structure of several types of oscillator is introduced in detail. A differential input delay unit based on transistor leakage is adopted to form a ring oscillator