Antenna-on-chip and antenna-in-package solutions to highly-integrated millimeter-wave devices for wireless communications

Abstract

Antenna-on-chip (AoC) and antenna-in-package

(AiP) solutions are studied for highly integrated millimeter-wave

(mmWave) devices in wireless communications. First, the background,

regulations, standard, and applications of 60-GHz wireless

communications are briefly introduced. Then, highly integrated

60-GHz radios are overviewed as a basis for the link budget

analysis to derive the antenna gain requirement. Next, in order

to have deep physical insight into the AoC solution, the silicon

substrate’s high permittivity and low resistivity effects on the AoC

efficiency are examined. It is shown that the AoC solution has low

efficiency, less than 12% due to large ohmic losses and surface

waves, which requires the development of techniques to improve

the AoC efficiency. After that, the AiP solution and associated

challenges such as how to realize low-loss interconnection between

the chip and antenna are addressed. It is shown that wire-bonding

interconnects, although inferior to the flip-chip, are still feasible in

the 60-GHz band if proper compensation schemes are utilized. An

example of the AiP solution in a low-temperature cofired ceramic

(LTCC) process is presented in the 60-GHz band showing an

efficiency better than 90%. A major concern with both AoC and

AiP solutions is electromagnetic interference (EMI), which is also

discussed. Finally, the systems level pros and cons of both AoC and

AiP solutions are highlighted from the electrical and economic

perspectives for system designers.