Rf Block Diagram - Nokia c2-00 Service Manual

RM-704
System Module

RF block diagram

Figure 73 RF block diagram
TX path overview
The TX digital architecture in the X-GOLD213 IC is based on a fractional-N sigma-delta synthesizer to generate
the two outputs at the TX1 port and TX2 port; LB and HB respectively. At The TX outputs, the AC coupled
Capacitors are removing the DC from the X-GOLD213 IC, the RF signal is then harmonic filtered by a H4 filter
(4th Harmonic Notch Filter) for LB and a H2 filter (2nd Harmonic Notch filter) for HB (both filter are series
resonance filter to GND), and attenuated by a 2dB attenuator before the FEM (PA+ antenna switch). The input
signal to the FEM is a GMSK RF modulated carrier signal in the range of -3dBm to +3dBm. The PA amplifies
the signal to its wanted output power level (PCL of the GSM specification) determined by the amplitude level
of the Vramp signal. The RF output signal from the FEM is delivered to the RF connector (RF production/debug
connector) if a RF cable is present or to the Antenna Pad in case of no RF cable connected. A detailed description
of the TX path in the RF part of the Quantum engine can be found in Appendix B.
RX path overview
The RX signal is input from the Antenna or from the RF connector if the RF cable is attached to the production
RF connector. The RF signal is then input to the antenna switch of the FEM, where it is switched to either the
LB path or the HB path. This is controlled by the settings of FE1/VC1 (TX-RX Switch), PABS/VC2 (Band Select),
and FE2/VC3 (Antenna Switch configuration); see the FEM logic table in Table 7. The antenna input signal is
then band-pass filtered in the SAW filter module with the RX in-band frequencies as specified in Table 1. After
BP filtering the RF signal is matched to the impedance of the X-GOLD213 IC differential inputs for optimum
receiver sensitivity performance. In the X-GOLD213 IC the RX input signals are amplified by a Low Noise
Amplifier (LNA) and down converted to Low IF and again amplified before demodulated and signal processed.
A detailed description of the RX path in the RF part of the Quantum engine can be found in Appendix A.
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