| With the improvement of the performance in electronic system products, with the industrialization of the nano-scale CMOS processes, and with the enhance of the integration of ICs, an electronic system construction appears which integrates large scale analog circuits, high-speed digital circuits and radio frequency circuits on ONE chip. That is called Mixed-Singal System-on-Chip, abbreviated SoC. In mixed-signal SoC, switching noise and power supply noise caused by high speed digital circuits will affect directly the characteristic of analog circuits and RF circuits, even the whole systemic circuit capability. Aimed at substrate noise in D/A converter, this thesis mainly discussed the production, propagation and injection of substrate noise generally.Based on the conception of substrate construction and analysing the origin of substrate noise coupling, this thesis proposes a substrate noise coupling model using resistance macro-model, and describes the substrate noise propagation and coupling mechanism in high-speed D/A converters. The substrate noise generated by clock signals and coding circuits in high-speed D/A converters, degrades the output performance of D/A converter by coupling substrate noise into current source cell circuits. In the end of this thesis, two kinds of substrate noise suppression technologies are proposed, which are low noise logical circuit based on current mode logic, and passive guard rings construction respectively. The simulation results show that they can attenuate the amplitude of substrate noise substantially, and prove the validity of these two technologies synchronously. All simulations are operated on Spectre simulator, with SMIC 0.18um mixed-signal process.These low substrate noise designing technologies based on current mode logic proposed by this thesis, can attenuate the amplitude of substrate noise effectively, and can be applied to the front-end design in mixed-singal and radio frequency circuits. |
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