Biointegrated electronics have been investigated for various healthcare applications which can introduce biomedical systems into the human body. Silicon-based semiconductors perform significant roles of nerve stimulation, signal analysis, and wireless communication in implantable electronics. However, the current large-scale integration (LSI) chips have limitations in in vivo devices due to their rigid and bulky properties. This paper describes in vivo ultrathin silicon-based liquid crystal polymer (LCP) monolithically encapsulated flexible radio frequency integrated circuits (RFICs) for medical wireless communication. The mechanical stability of the LCP encapsulation is supported by finite element analysis simulation. In vivo electrical reliability and bioaffinity of the LCP monoencapsulated RFIC devices are confirmed in rats. In vitro accelerated soak tests are performed with Arrhenius method to estimate the lifetime of LCP monoencapsulated RFICs in a live body. The work could provide an approach to flexible LSI in biointegrated electronics such as an artificial retina and wireless body sensor networks.
This letter presents a resonant tunneling diode (RTD)-based microwave amplifier operating at deep sub-milliwatt level dc-power. The fabricated amplifier, which is based on a reflection-type amplifying topology and uses an InP monolithic microwave integrated circuit technology, shows extremely low dc-power consumption of with a gain of more than 10 dB at 5.7 GHz. The amplifier performance is mainly enabled by the favorable characteristics of the InP-based RTDs biased at . The RTDs exhibit a high peak-to-valley current ratio (PVCR) of 11.2 with a low peak current of and thereby a relatively low negative resistance magnitude of . The dc-power consumption is about 6.4 times lower than that in transistor-based low-power amplifiers reported to date for the 5 GHz frequency band.Index Terms-MMIC amplifiers, negative resistance circuits, quantum effect semiconductor devices, resonant tunneling diodes (RTDs).
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