This paper presents a fractional 88-105 GHz frequency synthesizer module developed to support THz spectrometer instruments for planetary exploration. The presented module features low power operation and a small form factor to be compatible with the demanding payload requirements of NASA planetary missions. The core of the module is a CMOS System-on-Chip (SoC) containing a 50 GHz phase-lock loop and W-band frequency doubler, driven by a direct digital frequency synthesizer (DDFS) and DAC to provide finely tuned reference frequencies allowing fractional operation. The chip contains a wide range of calibration functions for temperature and radiation exposure compensation. The demonstrated module draws a total of 152 mW of power from a USB connection and provides coverage from 88-105 GHz with output powers up to -15 dBm. The offered mid-band phase noise is measured at 89.5 dBc/Hz evaluated at 1 MHz offset from the carrier.