Chapter 7: Communication Techniques EET-223: RF Communication - PowerPoint PPT Presentation

Chapter 7: Communication Techniques EET-223: RF Communication Circuits Walter Lara

Basic Frequency Synthesizer • Often a highly accurate and programmable frequency source is needed (function generators, spectrum analyzers, communication circuits) • Recall PLL, but add frequency divider (see Block Diagram in Fig 7-14) • Phase Comparator and the VCO make sure that f R = f out / N (assuming locked stated). So: f out = N f R • Notice f out is multiple of f R , so smaller f R gives better resolution (but oscillator drift also multiplied by N)

Figure 7-14 Basic frequency synthesizer.