VHF_frequency_synthesizer

Published:2009/7/23 22:39:00 Author:Jessie | From:SeekIC

The NF88C30 shown in this circuit contains all the logic required for a high-band VHF PLL synthesizer. Figure 2-41 shows the internal circuits or the chip. The components list is shown in Fig. 2-41 C. As shown in the PC-board layout of Fig. 2-41D, the ground place is split between the VCO and synthesizer-control sections, with dc connections made via narrow tracks on either side of the board.This construction prevents synthesizer currents from causing spurious sidebands in the VCO output. The VCO can be modulated externally by adding L5, D3, and VC2. The output spectrum is shown in Fig. 2-41E. The output power is 9.4 dBm into 50Ω, with a frequency swing of about 10 MHz (from 170 to 1 80 MHz in this case).



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