Offset Pll; A Noverview Of Offset Pll - Pantech G310 Service Manual

G310 Service Manual

4.2.5 Offset PLL

4.2.5.1 An Overview of Offset PLL
The Si4133T dual frequency systhesizer is a monolithic CMOS integrated circuit that performs IF
and RF synthesis. Two complete PLLs are integrated including VCOs, varactors, resonators, loop
filters, reference and VCO dividers, and phase detectors. Differential outputs for the IF and RF
PLLs are provided for direct connection to the Si4200 transceiver IC. The RF PLL uses two
multiplexed VCOs. The RF1 VCO is used for Receive mode, and RF2 VCO is used for Transmit
mode. The IF PLL is used only during Transmit mode and uses a single VCO.
The frequency synthesizer uses VC-TCXO(13MHz) as reference frequency. 13MHz of VC-TCXO is
sent to the frequency synthesizer as a reference input.
Fig.4-10. Si4133T Frequency Synthesizer Block Diagram
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