Signal integrity design for GHz high-speed differential wires with slip ring capsule

In order to improve the signal quality of the slip ring capsule, twisted lines are utilized to significantly reduce the reflection among the devices. By twisting the differential parallel lines, the variant differential-mode impedance on the two parallel lines with different spacings from 160 ohm to 238 ohm is improved to have stable one, which is approximately 115 ohm. The discontinuities along the differential parallel wires can be minimized and it also improves the quality of data transmission by twisting the differential lines. According to the eye diagram of measuring the slip ring capsule with twisting lines in data rate of 1 Gbps, the eye height is enlarged from 80 mV to 487 mV and the eye width is increased from 417.8 psec to 924.8 psec, respectively, as compared with the one with untwisted lines. Even if the data rate is raised to 2 Gbps, the slip ring capsule with twisted line can still have acceptable eye height and eye width, which is 241 mV and 373.6 psec, respectively.