Innovative Technical Systems has developed high-performance agile microwave synthesizers with truly phase-coherent frequency switching at any step size. These synthesizers offer frequency coverage from 250 MHz to 18 GHz (ACS-25018) or 850 MHz to 18 GHz (ACS-85018) and frequency resolution under 0.1 Hz. The agile design offers typical switching speeds of less than 300 nsec and programmable amplitude from 0 to +10 dBm from frequency-to-frequency. Spurious performance is typically <-70 dBc. A versatile waveform table design is implemented that allows frequency, amplitude, and output markers to be defined for each step in the table. Waveform table lengths up to 256K are supported.