A new line of USB-controlled, phase locked loop (PLL) frequency synthesizers has recently been launched. In RF and microwave communications systems where signal integrity is a priority, PLL synthesizers offer superior frequency stability and accuracy with exceptional phase noise characteristics that allow components in the signal chain to perform at their optimal levels. These PLL synthesizers are ideal for applications that involve electronic warfare, signal generators, benchtop test and measurement, and microwave radio. These six new models are compact, rugged, SMA-connectorized designs that support USB 2.0 interface with a PC computer supplying DC power and GUI command control. They cover a broad range of frequency bands from 25 MHz to 27 GHz. These models deliver output attenuation that is adjustable up to 50 dB in 1 dB steps, and high output power levels ranging from +10 to +19 dBm typical. Phase noise is as low as -108 dBc/Hz at 100 MHz offset and phase locked speed is 1 msec typical. These synthesizer models also feature a 50 MHz internal frequency source and optional external reference with supplied cable.