Modeling and analysis of a trace referenced to a meshed ground plane

Offset mesh in FPCB for better impedance control

“…In such cases, meshed ground planes are used for impedance matching [1]. However, characteristic impedance still varies significantly depending on whether a routed trace lands on top of apertures, lands on top of a solid plane or is placed in between [2]. Furthermore, if two traces make up the two legs of a differential pair, they see different effective dielectric constant values [3], which causes intra-pair skew.…”

Improving Signal Integrity by Reducing Mode Conversion in Differential Pairs on a Meshed Ground in Flexible Printed Circuit Boards

“…In this way, if a routed trace lands on a solid region of the top layer, it should land on top of an aperture region on the bottom layer (or vice versa). There are mainly three variables in designing a mesh plane: (1) a trace-to-aperture intersecting angle, (2) the ratio of the aperture to the solid region, and (3) the position of the trace on the meshed plane [6].…”

“…The use of flexible printed circuit boards (FPCBs) in electronic devices has been increasing as these devices become thinner and smaller. Meshed ground planes have been adopted in FPCBs for impedance matching and improved flexibility [1][2][3][4][5][6][7][8]. Apertures of meshed ground planes cause an effective dielectric constant change and a roundabout current path that increase the inductance of the ground plane [9].…”

Mitigating differential skew by rotating meshed ground for high-density layout in flexible printed circuits

“…In addition, it is challenging to arrange the lines and the meshed ground completely symmetrically in actual production [13]. If the two are even slightly asymmetrical, the characteristic impedance changes [14,15,16], causing mode conversion and differential skew [17,18,19].…”

“…When the angle between the wiring and the meshed ground (i.e. the rotation angle) is 0 or 45 • , the characteristic impedance is heavily affected by the arrangement, but the effect is slight in the range of 10 to 40 • , and around 22.5 • , the effective characteristic impedance is unaffected by the wiring position [14]. Based on this, this study focuses on the differential transmission lines and discusses the phase delay difference (differential skew) between two lines.…”