AN31
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FOR THE
INDUCTOR DESIGN
1. Introduction
Si41 X X S Y N T H E S I Z E R F A M I L Y
3.1. Using a Discrete “Chip” Inductor
If the required value for LEXT is greater than 3 n H, it is remended that a discrete “chip” inductor be used. This inductor should be placed as close as possible to the device pins as shown in Figure 1. printed trace
Silicon Laboratories’ family of frequency synthesizers integrates VCOs, loop filters, reference and VCO dividers, and phase detectors in standard CMOS technology. Depending on the synthesizer being used, the frequency of operation may require an external inductance to establish the desired center frequency of operation. This may be implemented with either a printed circuit board (PCB) trace or a discrete “chip” inductor. This application note provides guidelines for designing these external inductors to ensure maximum manufacturing margin for frequency tuning. discrete inductor J
2. Determining LEXT
The center frequency for many of Silicon...
