SNLS315H April 2010 – August 2015 LMH0387
PRODUCTION DATA.
For information on layout and soldering of the laminate TLGA package, refer to the following application note: AN-1125 (SNAA002), Laminate CSP/FBGA.
NOTE
For a CSP package, it is a general requirement not to have any metal (traces or vias) on the top layer in the area directly underneath the device, other than the footprint. This is intended to provide a flat planar surface for the package.
The ST 424, 292, and 259 standards have stringent requirements for the input and output return loss of receivers and transmitters, which essentially specify how closely they must resemble a 75-Ω network. Any non-idealities in the network between the BNC and the LMH0387 will degrade the return loss. Take care to minimize impedance discontinuities both for the BNC footprint and for the trace between the BNC and the LMH0387 to ensure that the characteristic impedance is 75 Ω. Best return loss performance is achieved with the LMH0387 placed closely to the BNC to minimize the trace length between the BNC and the LMH0387's BNC_IO pin. Consider the following PCB recommendations: