本論文使用位移時間差動訊號的概念，來降低因路徑不相等而造成的模轉換，內容包含了九十度彎角差動傳輸線、差動蛇線和彎角強耦合差動蛇線，其改良結果分述如下。
首先，為了消除九十度彎角差動傳輸線的時域穿透共模雜訊，我們使用位移時間差動訊號，來減少九十度彎角差動傳輸線的路徑差。量測到的TDT共模雜訊峰值電壓，為0.019 V，遠比沒加位移時間差動訊號的九十度彎角差動傳輸線的TDT共模雜訊電壓0.065 V來得小。另外，量測到的TDR差模雜訊峰值電壓，為0.023 V，亦比沒加位移時間差動訊號的九十度彎角差動傳輸線的時域反射差模雜訊電壓0.033 V來的小。接下來，為了比較頻域S參數的特性，我們推導了位移時間九十度彎角差動傳輸線的等效S參數。由模擬結果我們可知，位移時間九十度彎角差動傳輸線，可以大大地降低差模到共模的模轉換，從DC到6 GHz的頻帶內，有大於或等於7 dB以上的降幅。另外，使用位移時間九十度彎角差動傳輸線，並不會增加差模或是共模的反射。再者，位移時間九十度彎角差動傳輸線，可以增加差模到差模的穿透。並且，其差模到差模穿透的相位也有很好的線性度。最後，我們萃取了位移時間九十度彎角的等效電路參數，從這些等效電路參數我們可知，因為位移時間九十度彎角的內側路徑的自感L13=2.0822 nH相當接近外側路徑的自感L24=2.0688 nH，並且，其內側路徑自容C11= C33=0.16837 pF相當接近外側路徑自容C22= C44=0.2535 pF，因此，當輸入一個差動訊號時，內側路徑與外側路徑上的訊號較能同時抵達接收端，造成較小的差模到共模的模轉換。
接著，我們探討了差動蛇線和彎角強耦合差動蛇線的模轉換。首先，我們提出了位移時間差動蛇線，來降低偶數對差動蛇線的共模雜訊。位移時間差動蛇線的模轉換，從DC到15 GHz皆小於–13 dB，和差動蛇線的模轉換比較，在整個頻帶內模轉換有降低的趨勢。而TDT共模雜訊峰值電壓，從原先的0.0289 V大幅降至0.0117 V，並且，其TDR差模雜訊峰值電壓沒有增加。接下來我們也提出了位移時間之彎角強耦合差動蛇線，從DC到15 GHz皆小於–18 dB，和彎角強耦合差動蛇線的模轉換比較，在整個頻帶內模轉換有降低的趨勢。而TDT共模雜訊峰值電壓，從原先0.0154 V降至0.0065 V，並且，其TDR差模雜訊峰值電壓沒有增加。為了驗證上述差動蛇線和彎角強耦合差動蛇線加上位移時間差動訊號的效果，我們使用降頻放大的方法，將整體電路放大了5.72倍。降頻放大的電路經過實際量測後與模擬的結果相當吻合，證明了模擬結果的正確性。

In this thesis, the timing-offset differential signal is proposed to eliminate the differential-to-common mode conversion induced by the unequal paths of the bended differential transmission line, which includes the bended differential transmission line using the right-angle bend, differential serpentine delay line and differential serpentine delay line with strongly-coupled turns. The improvement is demonstrated as follows.
First of all, in order to eliminate the TDT common mode noise of bended differential transmission line using the right-angle bend, the timing-offset differential signal is applied on the bended differential transmission line. The measured TDT common-mode noise is about 0.019V, which is much smaller than 0.065V of the bended differential transmission line without the timing-offset signal. Besides, the measured TDR differential-mode noise is about 0.023V, which is also smaller than 0.033V of the bended differential transmission line without the timing-offset signal. Furthermore, in order to investigate the frequency-domain S-parameters, we introduce the idea of equivalent S-parameters for the timing-offset bended differential transmission line. According to the simulation results, the timing-offset bended differential transmission using the right-angle bend can substantially reduce the mode conversion, which has 7 dB improvement from DC to 6 GHz. Besides, the timing-offset bended differential transmission line using the right-angle bend does not increase the differential-mode or common-mode reflection at the sending end. Also, it can increase the differential-mode to differential-mode transmission at the receiving end. In addition, the phase of the differential-mode to differential-mode transmission has a linear response. Finally, in order to investigate the insights of the reduction of the mode conversion, we extract the equivalent circuit parameters of the timing-offset bended differential transmission line using the right-angle bend. According to the equivalent circuit parameters, since the self-inductance (L13=2.0822 nH) of the inner path is quiet close to the self-inductance (L24=2.0688 nH) of the outer path and the self-capacitance (C11= C33=0.16837 pF) of the inner path is also close to self-capacitance (C22= C44=0.2535 pF) of the outer path, the differential signal on the inner and outer paths will approximately reach the receiving end at the same time, causing a great reduction in the common noise.
Secondly, we investigate the differential serpentine delay line and differential serpentine delay line with strongly-coupled turn. Owing to the even number of the coupled delay line, the lengths of the inner and outer paths become unequal, inducing the common mode noise at the receiving end. In order to reduce the common mode noise, the timing-offset differential signal is applied on the differential serpentine delay line. The mode conversion of the timing-offset differential serpentine delay line is below –13dB from DC to 15GHz. As compared with mode conversion of the differential serpentine delay line, the mode conversion is reduced. Besides, the amplitude of the TDT common-mode noise at the receiving end is reduced from 0.0289 V to 0.0117 V whereas the amplitude of the TDR differential-mode noise at the sending end is not increased. Furthermore, the timing-offset differential signal is applied to the serpentine delay line with strongly-coupled turn so as to further reduce the common mode noise. The mode conversion of the timing-offset differential serpentine delay line with strongly-coupled turns is below –18dB from DC to 15GHz. As compare with the mode conversion of the differential serpentine delay line with strongly-coupled turns, the mode conversion is decreased. Besides, the amplitude of the TDT common-mode noise at the receiving end is reduced from 0.0154 V to 0.0065 V whereas the amplitude of the TDR differential-mode noise at the sending end is not increased. In order to verify the simulation results of the timing-offset serpentine delay line and timing-offset serpentine delay line with strongly-coupled turns, 5.72 times scaled down serpentine delay lines are fabricated and measured. The measurement results of the scaled down circuits, which are in good agreement with the simulation results, verifies our designs.

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