In this thesis, electronic packaging technology was introduced and discussed from the device level to system level, followed by a review of crosstalk suppression, thermal management and electro-thermal modelling of electronic packages. The first dynamic electro-thermal UCSD HBT model for the OMMICTM DH15IB InP process was developed in an electro-thermal simulator fREEDATM. Simulations were performed for the devices and a demonstrator amplifier in fREEDATM and Agilent™ ADS. The results showed how the thermal effects influenced the electrical behaviour. Static DC IV measurements and S parameter measurements were applied to verify the simulation results. At package level, a transmitter System-in-Package (SiP) demonstrator was developed. It was modelled and analyzed with a multi-physics simulator COMSOL Multiphysics™. A Low Temperature Co-fired Ceramic (LTCC) antenna array at 65GHz was designed for this SiP package demonstrator. Thermal vias were demonstrated to have positive effects on the package thermal management by simulation. An embedded chip package based on a new die attachment method was also electrothermally modelled and simulated with COMSOL Multiphysics™. The results have a good agreement with the measurement results based on a Temperature Co-efficient of Resistance (TCR) technique. Hypodermic thermocouples were also used for direct temperature measurement. Impact of different numbers of contact windows and different sizes of outer guard rings in the Ground Plane Silicon-on-Insulator (GPSOI) crosstalk suppression test structures were studied for the first 'time. Measurements, modelling and simulations were performed for a series of test structures in this work. An equivalent lumped circuit model for the test structure was developed for further investigation of crosstalk isolation. Conclusions were drawn that more contact windows on the GSG ground rails can generate better crosstalk reduction and that guard rings should have appropriate sizes and not be positioned far away from the devices in order to be effective on the crosstalk isolation.