power amplifier and duplex switch. The I/Q signal is inputted to be performed signal
modulation as the modulation signal. The modulated TXIF signals restrain its third
harmonic by harmonic suppression filter. The follow-up TXIF signal will be sent to a
discriminator on the offset frequency phase lock loop (OPLL). Then perform
frequency discrimination to this signal and the mixed signal of TXVCO signal and
RFVCO output signal. The discriminator outputs the signal control RFVCO and
RFVCO phase is enabled to lock at the phase of TXIF signal. TXVCO output RF is
still decided by RFVCO frequency. The phases of RFVCO and IFVCO signals lock at
the phase of VCTXO reference signal. TXVCO output signal is sent to emission
power amplifier (PA) A17/A16 pin to amplify. The TX signal outputted by PA pin
27is transmitted to the antenna via antenna switch to launch.
1.4 Base band circuit
Base band main chip adopts SC6820 chip.
1.5 Function circuit
WIFI/BT
T card
SIM card
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