Analysis of intra-chip degital noise coupling path in fully LTE compliant RF receiver test chip

Intra-electromagnetic noise coupling paths from RF-digital to RF receiver front end can be either of air, wire conduction, Si substrate or package/board. In this paper air and wire conduction coupling paths analysis is discussed. A miniature magnetic near field probe is applied to scan over the test chip to map magnetic near field at LTE band 1(2.1 GHz range). The map is reviewed to extract those on-chip wires that may transfer noise from digital to RF circuits. The extracted wire traces are compared with CAD drawings to build up the FEM simulation model. Each wire is terminated by particular impedance obtained by circuit simulation. The analysis clarified that the magnetic film suppressed conduction noise in on-chip control wires. Simulated total suppression of 11.5 dB well explains the measured suppression of 10 dB.