Graph-X aims at the development of a novel hardware platform based on graphene photonic integrated circuits for ultra-high speed and scalable sub-THz D- (110-170 GHz) and H-band (170-240 GHz) wireless links. The proposed technology will be the basic building block for high-speed radio back haul links, multi beam forming antennas for massive MIMO, short distance high resolution RADAR sensing. GraPh-X targets the distribution and detection of multi Gbit/s radio signals over sub-THz tunable carrier frequencies. The main outcome of GraPh-X will be a monolithic electronic and photonic chip (EPIC) that will constitute the basic building block of a completely new class of photonic/electronic antenna arrays for the next generation sub-THz communication and RADAR systems. The proposed approach will allow to overcome the technical bottlenecks of current sub-THz technology, such as increasing detrimental effect of phase noise at higher carrier frequencies, and carrier frequency stability. To reach the goal, the wafer scale graphene photonic technology is needed and must go beyond the state of the art. A new technique (HMG-Stack technology) will be developed to allow multi-stacking of graphene layers maintaining the same properties of single layer graphene. The key component of GraPh-X is a novel optoelectronic efficient frequency mixer able to mix two optical wavelengths and a high data rate electrical signal. The photonic chip will be realized using a SiN photonic platform that will integrate HMG-Stack as active material. The monolithic integration of the graphene photonic mixer with SiGe BiCMOS electronics for mmWave amplification will enable high output power and reduced footprint (<500x500µm2), matching the requirements of a single element of mmWave antenna array system.