PLL Synthesizer with Very Low Discrete Spurious

Frequency, transient and noise numerical analysis of a triple active RC notch filters (ARCN filters) are presented in this contribution. ARCN filters analyzed here are used for additional damping of the first unwanted harmonics (1., 2. and 4. ) at the phase detector output voltage. Every additional passive filter inside the PLL very often causes instability due to its too big additional phase shift. On the base numerical simulations results it is possible to design good ARCN filters with small phase shift within active PLL bandwidth. Also the noise analysis and noise optimization of such filters was carried out.