具有平均电压反馈的高精度振荡器的设计

发布时间：2018-01-15 11:48

  本文关键词：具有平均电压反馈的高精度振荡器的设计　出处：《电子科技大学》2015年硕士论文　论文类型：学位论文

  更多相关文章： 高频RC振荡器 平均电压反馈 比较器延迟

【摘要】：自晶体振荡器发明以来,由于其拥有稳定度高、频率抖动小的优点而广泛应用于各类精密仪器与系统中。而随着晶体管的问世,与其加工工艺水平的不断提高,各类系统已经开始由分立器件向单片集成发展。将原来的片外振荡器以片内集成的形式实现能大幅减少成本,降低功耗。张弛振荡器具有与标准CMOS工艺相兼容的优势,在片上系统、生物医疗传感器、高速接口以及微型计算机等应用领域大量采用。张弛振荡器采用反复对电容充放电的形式形成振荡方波输出,当电压达到比较器翻转点时改变充放电状态,但是,比较器延迟易受电源、温度等影响,因此振荡器频率精度受限。尤其是高频率振荡器的设计中,比较器延迟的影响更加突出。本文采用了一种平均电压反馈结构稳定比较器延迟。平均电压反馈结构通过在基准电压和比较器之间插入有源滤波器实现,平均电压反馈环路通过自动调节有源滤波器的输出来使有源滤波器的两输入端直流电压相等,最终实现稳定的输出频率。当比较器延迟增加时,有源滤波输出增加,比较器延迟减小时,有源滤波输出减小。得益于平均电压反馈,本文采用的比较器结构非常简单,而在普通张弛比较器中,比较性能要求较高。使得最终的振荡频率只由无源器件电阻、电容和相对稳定的比较器延迟确定。本文的振荡器主要针对开关电源的应用场合而设计,通过与开关电源中原有振荡器相比较,在振荡频率,比较器延迟等性能指标上有较大改善。最终实现10MHz量级的50%占空比方波输出,通过分频率模块可实现2.5MHz的输出,最终的占空比也可通过数字电路降低,以适应现有开关电源应用对振荡器的需求。振荡器输出的温度系数主要由电阻决定,在对电阻进行温度补偿后,从30℃至120℃输出频率有0.3%的变化。电源电压从2.7V至3.9V变化时,输出频率改变2%。本次设计基于0.13μm CMOS工艺实现,输出结果通过trimming在6MHz-10MHz内可调。最终绘制了版图,进行了流片。
[Abstract]:Since the invention of crystal oscillator, it has been widely used in various precision instruments and systems because of its advantages of high stability and low frequency jitter. All kinds of systems have begun to develop from discrete devices to monolithic integration. It can greatly reduce the cost to realize the original Oscillators in the form of in-chip integration. Reduce power consumption. Relaxation oscillators have the advantage of compatibility with standard CMOS processes, on-chip systems, biomedical sensors. High speed interface and microcomputer are widely used. Zhang Chi oscillator uses the form of repeated charge and discharge of capacitance to form oscillatory square wave output, which changes the state of charge and discharge when the voltage reaches the switching point of comparator. However, the comparator delay is easily affected by the power supply, temperature and so on, so the oscillator frequency accuracy is limited, especially in the design of high-frequency oscillator. In this paper, an average voltage feedback structure is used to stabilize the comparator delay. The average voltage feedback structure is realized by inserting an active filter between the reference voltage and the comparator. The average voltage feedback loop automatically adjusts the output of the active power filter to make the DC voltage of the two inputs of the active filter equal and finally achieve a stable output frequency. When the comparator delay increases. The active filter output increases, the comparator delay decreases, the active filter output decreases. Thanks to the average voltage feedback, the comparator used in this paper is very simple, but in the ordinary Zhang Chi comparator. The final oscillation frequency is determined only by passive device resistor, capacitance and relatively stable comparator delay. The oscillator is designed for the application of switching power supply. By comparing with the original oscillator in the switching power supply, the performance indexes such as oscillation frequency and comparator delay are greatly improved. Finally, the output of 10 MHz 50% duty cycle analogy wave is realized. The output of 2.5MHz can be realized by frequency division module, and the final duty cycle can be reduced by digital circuit. The output temperature coefficient of the oscillator is mainly determined by the resistor, after the temperature compensation of the resistor is carried out. The output frequency varies from 30 鈩，

本文编号：1428204