High speed intra-pair de-skew circuit

Abstract

For differential signal transmission (especially in high speed applications), intra-pair skew between paths carrying complementary portions of a differential signal can significantly affect performance. Conventional de-skew circuits employ simple filters (i.e., low-pass filters) to operate as delay elements to account for skew; however, these filters can distort the differential signal, which can also adverse affect performance. Here, an all-pass, adjustable delay element and de-skew circuit are provided to allow for compensation of skew without degrading the differential signal as conventional circuit do and, thus, having better performance characteristics.

Description

technical field [0001] The present invention relates generally to differential signaling, and more particularly, to deskewing differential signals. Background technique [0002] In many applications, differential signals are transmitted over different paths (ie, cables), which have different characteristics (ie, lengths). These differences in the signal paths can create skew between complementary portions of the differential signal (known as intra-pair skew) and can adversely affect performance, especially in high speed applications. Traditionally, analog de-skew circuits usually use filters as delay elements (eg, low-pass filter 100 in FIG. 1, which uses resistor R1 and capacitor C2). Although these filters delay a portion of the differential signal, these filters can have significant frequency attenuation that adversely affects the rise and fall times of the portion of the differential signal, as shown in FIG. 2 . Accordingly, there is a need for delay elements and deske...

AI Technical Summary

Problems solved by technology

Although these filters delay a portion of the differential signal, these filters can have significant frequency attenuation that adversely affects the rise and fall times of that portion of the differential signal, as shown in Figure 2

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