Design and implementation of liquid-based fine-tunable solenoid mems inductor
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Date
2018-04-01
Authors
Ahmad Hafiz Mohamad Razy
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Abstract
Passive devices such as on-chip inductors play an important role in radio frequency circuits. However, these types of inductor lacked in terms of quality factor performance due to high substrate parasitic. Thus, in this thesis, liquid-based fine-tunable solenoid microelectronic mechanical systems inductor with high quality factor is presented for ultra-high frequency applications. The light hydrocarbon-based ferrofluid is utilised in the design to achieve a fine-tuning inductance. A micro-tube acts as a channel for tunability. In addition to that, wire bonding technique is applied to reduce series resistance, substrate loss, and self-resonance loss. A gold wire is bonded diagonally at the edge of metal pad by crossing it over the top of the micro-tube. The designed inductor was simulated using ANSYS HFSS and measured at a frequency of 400 MHz for proof-of-concept work. At 400 MHz, simulation results show that the quality factor increases from 10 to 12 with inductance values tuning from 7.48 nH to 9.06 nH for empty channel and fully-injected channel, respectively. Thus, tuning range of 21% is successfully achieved. The measured results however, reveals that, at 400 MHz, the quality factor gradually decreases from 6.79 to 5.49 with inductance values tuning from 21.40 nH to 22.40 nH for empty channel and fully-injected channel, respectively, giving a tuning range of 4.67%. In conclusion, the design of liquid-based fine-tunable solenoid microelectronic mechanical systems inductor is proven workable for ultra-high frequency applications.