· Vbat lines from connector to PA and VCC1,2,3 of transceiver.
· RF Traces: Transceiver to PA, PA to ANT and ANT to LNA.
· APC control: PAC_Out.
· TX_I/Q and RX_I/Q.
· AFC control trace (Pin19 of sky74117)
· Crystal to Pin18 of sky74117
· 13/26MHz reference clock to baseband
· Separate the VBAT traces from PA to transceiver, other device, and so on.
· Keep the PA supply trace and return path far away from the sensitive circuits.
· All power supply filters should be put near the relevant components. And the rule is the smallest capacitance is the nearest.
· The value of 33uF cap depends on the noise level on the phone boar，可根据实际情况修改电容值。
· Depending on phone board noise level, not all 0402 and 0.01uF caps may be needed.
· Ensure sufficient numbers of vias connect VBATT pin to battery trace.
· VBATT trace should be >= 0.25mm.
· Ground terminals of all bypass caps are connected to ground plane with vias.
· The PAC_OUT trace from baseband should be surrounded by ground.
· DC supply trace to Vcc1 must not be routed via Vbatt pin.
DC supply trace to VCC1 must not be routed via VBATT pin.
DC supplies to 1st stages of GSM and DCS/PCS PAs. Routing from Vcc1A to battery should not via PIN VBATT.
DC supplies to 2nd stages of GSM and DCS/PCS PAs and BiCMOS control circuitry. Routing from Vcc1B to battery should not via PIN VBATT.
DC supplies to final stages of PAs. Current drawn on this pin is due to PA output stages only. A large bypass capacitor is required on this pin due to high current draw.
· Differential I and Q signal pairs should be parallel and symmetry and should be surrounded by ground on both sides, plus ground above and below if routed on internal layers.
· Routed the RF traces as microstrips or striplines with 50 ohm impedance, and should be as short as possible.
· Clear internal layer of metal immediately below RF microstrips to allow wider traces as well as reduce parasitic capacitance.
· Use enough ground vias to connect RF ground fill area to the internal ground plane.
· The line XTUNE from baseband to SKY74117 pin 19 should be surrounded by ground on both sides, plus ground above and below if routed on inner layers.
· XBUF (26MHz clock) from SKY74117 pin 18 to baseband should be surrounded by ground on both sides, plus ground above and below if routed on inner layers.
· Trace direction in adjacent layers: Vertical, not parallel.
· The RF part and Baseband part should be shielded respectively.