Microwave and Millimeter-Wave Monolithic Integrated Circuits in CMOS and GaAs-mHEMT Technologies

Doctoral thesis, 2008

The objective of this work has been to design and characterize microwave and millimeter-wave components and circuits within a 90 nm Si-CMOS process and a 100 nm GaAs-mHEMT process. The work is divided in two parts depending on the technology. In part one, which deals with components and circuits in Si-CMOS technology, two options for implementing microstrip transmission lines into the CMOS process are studied and compared. Novel miniature structures for baluns and power dividers are presented. The designs utilize, for the first time, a triple-coupled line. Compared to traditional couplers this approach offers substantial reduction in size, which in turn results in lower losses. The balun and the power divider based on this structure, have excellent phase and amplitude balance of better than 0.5 dB and 4 degrees respectively, over more than an octave bandwidth. Furthermore, a novel compact capacitor called fringing-field-enhanced capacitor is introduced. The proposed design makes extensive use of the fringing fields between capacitively coupled vias and offers considerable size reduction and improvement in the Q-factor compared to conventional integrated capacitors. No additional material or process steps are needed. Finally, two single-ended resistive mixers, operating at 20 and 60 GHz, have been designed and characterized. The mixers show excellent performances with minimum conversion loss of 7.9 and 11.6 dB, respectively. Experimental results show that by applying selective drain bias, the intermodulation performance of the mixers, while driven by moderately low LO power, may improve. In part two, which discusses circuits in GaAs-mHEMT technology, a monolithic receiver consisting of a 210-GHz single-ended resistive mixer integrated with an on-chip antenna is designed and characterized. A double-sideband noise figure of 10 dB has been measured using hot/cold loads. Also a 210-GHz single-balanced resistive mixer has been designed and characterized. An LO-to-RF isolation of more than 39 dB has been measured for this mixer.