Reduction Techniques for Digital Substrate Noise on Mixed-Signal Integrated Circuits

随着多媒体技术的发展，对高性能混合信号集成电路的需求日益增加。数字电路的周期性行为会产生所谓的数字衬底噪声。这种噪声会降低模拟电路的性能，是一个亟待解决的大问题。然而，它只抑制了通过衬底表面耦合的噪声，而对通过衬底深部传递的噪声影响很小。本计画提出一主动式屏蔽电路以解决数位基板杂讯问题。为了提高有源屏蔽电路的抵消性能，提出了模拟电路和数字电路相结合的有源屏蔽电路布局，并提出了一种自动控制技术。通过实验和仿真证实了所提出的技术的有效性。

Demands on high performance mixed-signal integrated circuits are increasing because of the advancing of multimedia technologies. Periodical behavior of digital circuits produces what so called digital substrate noise. This noise will deteriorate analog circuit performance and is a big problem to be solved.A passive guard ring has been commonly used to reduce the substrate fluctuation. However, it only suppresses the noise coupled through a substrate surface and has quite small effect on noise transfered through the deep portion of a substrate. This project proposes an active shield circuit to solve digital substrate noise problem. The proposed active shield circuit will generate an inverting signal to the digital noise and cancel out it. To improve cancellation performance layout of the active shield circuit, analog circuits and digital circuits is considered, and an automatic control technique is proposed. The validity of the proposed techniques is confirmed through experiments and simulations.