Abstract: A frequency-shift-keyed PLL frequency synthesizer with large frequency-muplication factor, with absolute frequency deviation independent of frequency-multiplication factor. The PLL also has fractional frequency-multiplication-factor programming capability. The PLL is inexpensive to implement, and potentially capable of fast frequency changing, due to lack of need to compensate modulator frequency deviation with possible resulting stabilization-time requirements, associated with each PLL output-frequency change. The PLL frequency synthesizer preferably employs a PLL-DRO and subharmonic mixer to achieve stable, low-noise microwave output frequencies.