LTE-A Module  Series 
                                                            EM120R-GL&EM160R-GL Hardware Design 
EM120R-GL&EM160R-GL_Hardware_Design                                                                         42  / 79 
 
 
 
Table 13: Description of PCIe Power-on Timing Requirements of the Module 
 
The following  principles  of PCIe  interface design  should  be  complied with  so  as to meet  PCIe V2.1 
specifications. 
 
⚫  It is important to route the PCIe signal traces as differential pairs with total grounding.   
⚫  For PCIe signal traces, the TX and RX differential data pair maximum length is recommended to be 
less than 250 mm, the TX and RX differential data pair matching are less than 0.7 mm (5 ps). 
⚫  Do not route  signal traces under crystals, oscillators, magnetic devices or RF signal traces. It is 
important to route the PCIe differential traces in inner-layer with ground shielding on not only upper 
and lower layers but also right and left sides. 
 
3.8.2.  USB Version and PCIe Only Version 
Beginning with ES2 (engineering samples), EM120R-GL&EM160R-GL support USB version and PCIe 
only version described as below: 
 
USB version: 
⚫  Support all USB 3.0/2.0 features 
⚫  Support MBIM/QMI/QRTR/AT 
⚫  Support firmware upgrade 
 
PCIe only version: 
⚫  Support MBIM/QMI/QRTR/AT 
⚫  Support BIOS PCIe early initial 
⚫  Support firmware upgrade 
 
If EM120R-GL&EM160R-GL work at PCIe only version by burnt eFuse, the modules cannot switch back 
to USB version. 
FULL_CARD_POWER_OFF# could be de-asserted 
before or after RESET#, 20 ms is a recommended value 
when it is controlled by GPIO. 
The host must ensure that the reference clock is in the 
active clock state for at least a period specified by 
TPCIE_RST_N-CLK, prior to PCIE_RST_N de-assertion.