Two-PLL forward Diophantine Frequency Synthesizer

Diophantine frequency synthesis (DFS) is a new approach to high-resolution, fast-hopping, low-spurs frequency synthesis. DFS is based on mathematical properties of integer numbers and employs two or more Phase-Locked Loops (PLL)s to achieve frequency resolution arbitrary smaller than the phase-comparator frequencies of the constituent PLLs. A two-PLL DFS synthesizer is presented that achieves frequency resolution about 100 times finer than that of the two constituent PLLs. It has output frequency range 195-205 MHz and frequency step 542 Hz. Measurements demonstrate the resolution of the architecture and the spectral purity of the output signal.