상세정보

This work presents methods for mitigating differential-to-common mode conversion noise in high-speed digital systems. As the modern high-speed digital signaling technologies demand faster data rate signals, electromagnetic interference (EMI) and electromagnetic compatibility (EMC) issues become more important than ever when designing high-speed digital systems. Also the density of printed circuit boards (PCBs) increases rapidly and integrated circuits are increasingly miniaturized, various trace discontinuities are inevitable in the design of high density PCBs. These trace discontinuities in PCBs make serious unwanted noise also known as differential-to-common mode conversion noise. The induced common mode noise can cause serious EMI issues, and degrade the signal integrity (SI) and power integrity (PI). In this thesis, various schemes are presented to suppress the differential-to-common mode conversion noise in various trace discontinuities in PCBs including right-angle bent differential lines, delay serpentine lines. Proposed methods for right-angle bent differential lines compensate the pahse differences between two differential lines and methods for delay serpentine lines equalize the even- and odd- mode velocities to mitigate mode conversion noise. Noise suppression characteristics are verified in both the frequency and time domains with S-parameters and eye diagram.

1 Introduction 1
1.1 Differential Signaling and Common-Mode Noise in High-Speed Digital Systems  1
2 Right-angle Bent Differential lines   5
2.1 Introduction  5
2.1.1 Differential-To-Common Mode Conversion With Right-Angle Bent Differential Lines  5
2.1.2 Right-Angle Bent Differential Lines with Asymmetric Coupled Lines  7
2.2 L-pad  9
2.2.1 Schematics  12
2.2.2 Simulation and Experimental Verification  12
2.3 Mushroom Structure  16
2.3.1 Right-angle Bent Differential Lines with The Mushroom Structure  16
2.3.1.1 Schematics  18
2.3.1.2 Dispersion Diagram Analysis For Differential-To-Common Mode Conversion Suppression  19
2.3.1.3 Simulation and Experimental Verification  28
2.3.2 Right-Angle Bent Differential Lines With Multiple Distributed Mushroom Structures  30
2.3.2.1 Schematics and Equivalent Transmission Line Model  30
2.3.2.2 Mode Conversion Suppression Bandwidth Enhancement  33
2.3.2.3 Experimental Verification   34
2.3.3 Eye diagram   38
2.3.4 Comparisons   40
2.4 Conclusions   40
3 Right-Angle Back-to-Back Differential Lines   43
3.1 Introduction   43
3.1.1 Remnant Mode Conversion Noises with Dual Back-to-Back Bent Differential Lines   43
3.2 Remnant Mode Conversion Noise Suppression with SMD Capacitor  48
3.2.1 Schematics   48
3.2.2 Eye Diagram   52
3.2.3 Comparisons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
3.3 Conclusions   55
4 Microstrip Differential Delay Lines  56
4.1 Introduction  56
4.1.1 Differential-To-Common Mode Conversion Noise With Differential Serpentine Delay Microstrip Lines  59
4.1.2 Length Difference in Turned Traces Section (tT )  62
4.1.3 Even- and Odd-mode Velocity Difference in Parallel Traces Section (ΔtP )  63
4.2 Serpentine coupled lines  65
4.2.1 Schematics   65
4.2.2 Simulations and Verification  68
4.3 Differential Serpentine Delay Microstrip Lines with Embedded Coupled Lines  69
4.3.1 Schematics  70
4.3.2 Differential-To-Common Mode Noise Suppression  74
4.3.3 Comparisons    77
4.3.4 Experimental Verification    80
4.3.5 Eye Diagram  82
4.4 Conclusions  83
5 Conclusions  86