Subharmonic 140 GHz Mixer Design in SiGe BiCMOS

Abstract

Many communication and remote sensing devices will inevitably move to higher frequencies where new challenges will be encountered by IC designers. To tackle this transition many of the circuit subsystems will have to be redesigned, these are antennas, amplifiers, mixers, and oscillators.

This thesis presents design, implementation, and simulation results of an integrated subharmonic mixer (SHM) as part of a 140 GHz direct conversion receiver for radiometry applications. The ability to use an LO with half or even a quarter of the frequency that would be otherwise required - can simplify the LO design and improve performance. At very high frequencies it becomes increasingly challenging to build a local oscillator able to provide enough power and with acceptable phase noise. Moreover, the use of a subharmonic mixer can effectively address the LO self-mixing issue commonly seen in direct conversion receivers.

The subharmonic mixer under 2.0 V supply voltage shows a maximum conversion gain of 8.6 dB; DSB noise figure of 14.9 dB; great linearity represented by IIP3 value of 1.65 dBm and IP1dB of -9 dBm. These results are further compared to the ones obtained from a prior literature review. With that, a key component for the integration of a millimeter-wave receiver frontend is realized successfully, demonstrating the potential of current state-of-theart SiGe processes.