On-chip millimeter wave circuit designs at 60GHz and 77GHz offer huge potentials for various wireless communication and radar applications. This paper investigates the implementation of on-chip balun, which is one of the important components in millimeter wave design. Particularly, we are interested in two types of passive structure: rat-race hybrid and Marchand balun. In the following sections, we are going to present an on-chip Rat-race Hybrid design and a Marchand Balun design in 0.13um BiCMOS technologies. Simulation results using 3D electromagnetic simulator will be shown and verified with hardware measurements.

On-chip millimeter wave Wilkinson power divider has been developed with the back end of line (BEOL) wiring and enabled as a library device in a 0.13 mum BiCMOS process design kit. The device layout and model are fully scalable, i.e. users can design a power divider at different frequencies or in different reference characteristic impedance systems by inputting the dimensions. Excellent model and hardware correlation has been observed up to 110 GHz. The measured results show that very good performance on-chip Wilkinson power dividers have been obtained in this technology, such as less than about 0.1 dB amplitude imbalance, about 0.8 dB of insertion loss with bandwidth of about 15% of the design frequency (defined at 15 dB return loss level) and about 20 dB of isolations. In addition, the device is the design rule check (DRC) clean and the layout versus schematic (LVS) enabled, which help to shorten the design cycle.

In this paper, the modeling, design, and measurement of on-chip compact millimeter-wave branch line couplers are discussed. These couplers are realized with the Back End of Line (BEOL) wiring and enabled as a library device of a 0.13 micron SiGe BiCMOS process design kit. Like other library devices, this coupler device has a scalable layout pattern and a schematic symbol, which allows users to have couplers at different frequencies by inputting the dimensions. An accurate model for these branch line couplers is developed, which shows a good match with the measurements of the couplers designed for 60GHz, 77GHz and 94GHz. Better than 19dB return loss, better than 1.5dB insertion loss and better than 21dB isolation have been observed. The side dimensions of these compact on-chip couplers are ranging from 440 microns to 530 microns.

Although the discontinuity structures in the microstrip transmission lines such as a gap have been largely studied, the three-dimensional edge effects, skin effects and metal losses have hardly been analyzed in the model. In this paper, an accurate model which enable high predictability for electrical behavior of on-chip 3-D transmission line with gap discontinuity is developed from equations generated with conformal mapping techniques. The model has also been used to develope gap as a library device with schematic symbol, layout parameterized cell (PCell). T-line with gap has been implemented with back end of line (BEOL) in 0.13 mum SiGe BiCMOS technology. Good correlations have been achieved up to 120 GHz among EM simulation, measurement and model, less than 2.3deg phase difference and less than 1.59 dB coupling magnitude have been achieved for all the cases. The model is scalable and can be used for the design of mm-wave passive components as well as the guideline for high density interconnects layout.

Feasibility of wideband on-chip RF switch operating at millimeter wave frequencies using PIN diodes in IBM .13 mum SiGe technology is demonstrated. A SPDT reflective switch targeting 60 GHz wireless and radar applications is designed, fabricated, and measured. Good correlations between simulation and hardware are reported. Measured data show 2.0 to 2.7 dB of insertion loss over 51 to 78 GHz bandwidth with better than 12 dB return loss and 25 to 35 dB of isolation.