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Integrated Inductors for RF Transmitters in CMOS/MEMS Smart Microsensor Systems

View Article: PubMed Central

ABSTRACT

This paper presents the integration of an inductor by complementary metal-oxide-semiconductor (CMOS) compatible processes for integrated smart microsensor systems that have been developed to monitor the motion and vital signs of humans in various environments. Integration of radio frequency transmitter (RF) technology with complementary metal-oxide-semiconductor/micro electro mechanical systems (CMOS/MEMS) microsensors is required to realize the wireless smart microsensors system. The essential RF components such as a voltage controlled RF-CMOS oscillator (VCO), spiral inductors for an LC resonator and an integrated antenna have been fabricated and evaluated experimentally. The fabricated RF transmitter and integrated antenna were packaged with subminiature series A (SMA) connectors, respectively. For the impedance (50 Ω) matching, a bonding wire type inductor was developed. In this paper, the design and fabrication of the bonding wire inductor for impedance matching is described. Integrated techniques for the RF transmitter by CMOS compatible processes have been successfully developed. After matching by inserting the bonding wire inductor between the on-chip integrated antenna and the VCO output, the measured emission power at distance of 5 m from RF transmitter was -37 dBm (0.2 μW).

No MeSH data available.


Comparison of the simulated inductance with the measured inductance of a planar spiral inductor.
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f6-sensors-07-01387: Comparison of the simulated inductance with the measured inductance of a planar spiral inductor.

Mentions: When the number of sides grows (square to circular geometry) the inductance grows faster than the resistance. It can be set as a design rule that an optimum inductor has to be designed with the highest number of sides allowed by the fabrication technology [10]. On the other hand, if the spacing is reduced, the quality to augment because the resistance is maintained and the inductance is increased be set as a design rule that to maximize the quality of an inductor has to be designed with smallest spacing allowed by the technology. The external radius and number of turns have been analyzed. They define the inductor's length. Figure 6 shows the influence of the number of turns comparing the measured results with simulated results. As the number of turns increases the inductance grows and the quality curve shifts to lower frequencies. However, an empirical analysis to set the design rule for the external radius and the number of turns is necessary. Figure 6 shows also the influence of the track widths. The track widths increase the inductance to diminution because more metal track length would be needed leading probably to higher DC resistance and coupling to the substrate [11].


Integrated Inductors for RF Transmitters in CMOS/MEMS Smart Microsensor Systems
Comparison of the simulated inductance with the measured inductance of a planar spiral inductor.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3814858&req=5

f6-sensors-07-01387: Comparison of the simulated inductance with the measured inductance of a planar spiral inductor.
Mentions: When the number of sides grows (square to circular geometry) the inductance grows faster than the resistance. It can be set as a design rule that an optimum inductor has to be designed with the highest number of sides allowed by the fabrication technology [10]. On the other hand, if the spacing is reduced, the quality to augment because the resistance is maintained and the inductance is increased be set as a design rule that to maximize the quality of an inductor has to be designed with smallest spacing allowed by the technology. The external radius and number of turns have been analyzed. They define the inductor's length. Figure 6 shows the influence of the number of turns comparing the measured results with simulated results. As the number of turns increases the inductance grows and the quality curve shifts to lower frequencies. However, an empirical analysis to set the design rule for the external radius and the number of turns is necessary. Figure 6 shows also the influence of the track widths. The track widths increase the inductance to diminution because more metal track length would be needed leading probably to higher DC resistance and coupling to the substrate [11].

View Article: PubMed Central

ABSTRACT

This paper presents the integration of an inductor by complementary metal-oxide-semiconductor (CMOS) compatible processes for integrated smart microsensor systems that have been developed to monitor the motion and vital signs of humans in various environments. Integration of radio frequency transmitter (RF) technology with complementary metal-oxide-semiconductor/micro electro mechanical systems (CMOS/MEMS) microsensors is required to realize the wireless smart microsensors system. The essential RF components such as a voltage controlled RF-CMOS oscillator (VCO), spiral inductors for an LC resonator and an integrated antenna have been fabricated and evaluated experimentally. The fabricated RF transmitter and integrated antenna were packaged with subminiature series A (SMA) connectors, respectively. For the impedance (50 Ω) matching, a bonding wire type inductor was developed. In this paper, the design and fabrication of the bonding wire inductor for impedance matching is described. Integrated techniques for the RF transmitter by CMOS compatible processes have been successfully developed. After matching by inserting the bonding wire inductor between the on-chip integrated antenna and the VCO output, the measured emission power at distance of 5 m from RF transmitter was -37 dBm (0.2 μW).

No MeSH data available.