采用COSTAS环路的全制式音视频IF锁相环设计

一种能解决全电视制式的音视频锁相环设计,在I2C总线控制下与AFC(数字自动频率控制)相配合,完成了视频信号与音频信号的快速捕捉锁定与实时追踪,解决了调谐器需要人为操控完成制式转换的问题。文章详细阐述了完整设计过程,解决了模块级设计、仿真验证与版图设计中的关键技术。该设计的电路模块包括偏置电路及其启动电路、基准电压源、FPLL检波器、压控振荡器、窄带FM-PLL、Nf频率合成器、数字AFC、I2C总线控制器等。并对模拟乘法器、COSTAS环鉴频辅助器、VCO振荡控制范围及低噪设计、窄带PD等功能以及完整系统,采用Spectre仿真器进行了仿真验证。电路设计兼顾双极模拟电路与数字电路的优点,电路结构设计充分考虑了应用兼容性,并在音视频信噪比、锁相精度等多项性能指标上有了很大提高,使用外围简单且操作灵活。

COSTAS Loop Controlled All Standard Audio and Video IF-PLL Demodulators Design

This circuit design can solve all standard video and audio of the PLL, it is under the control of the I2C bus compatible with digital AFC to complete the video signal and audio signal fast capture lock and simultaneously track to solve the tuner need to complete the format conversion manipulated the process. This paper explains in detail the design process, especially the module design, simulation and layout design of the key technology. The design of circuit module includes a bias circuit and starting circuit, a voltage reference source, the FPLL detector, a voltage controlled oscillator, a narrowband FM-PLL, Nf frequency synthesizer, digital AFC, I2C bus controller. Spectre simulator used in that circuit module and system simulation, verify analog multiplier, COSTAS loop discriminator auxiliary device, VCO oscillation control range and low noise design, narrowband PD etc. Circuit design consideration of bipolar analog circuit and digital circuit, circuit structure design fully consider the use of compatibility, and on several performance metrics do greatly improved, it using simple peripherals.