Improving the Signal Integrity, Impedance Control and Attenuation of the Thin Transmission Lines Printed on Flexible Substrates

The uniform transmission line printed on flexible substrates distorts high speed and high frequency signals due to its thin thickness and thus high parasitic resistance. Though the coplanar waveguide can alleviate this issue to certain extent but the cost is very high because of the much wider line widths used. In this paper we propose to use tapered transmission lines to improve the signal integrity for high speed digital signals, to keep designated impedance and to decrease signal attenuation for high frequency RF signals. Printed tapered transmission lines are divided into two types: linearly tapered and segment-wise tapered. The DTR impedances, time domain signal propagations and S-parameters were simulated for uniform transmission line, proposed tapered transmission lines and coplanar waveguide. The results show that printed tapered thin microstrip transmission lines are suitable to be interconnects for heterogeneous integration of silicon chips and printed electronic devices on flexible substrates.