Jooseok Lee

In Vivo Silicon-Based Flexible Radio Frequency Integrated Circuits Monolithically Encapsulated with Biocompatible Liquid Crystal Polymers

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.

An On–Off Mode RTD Oscillator Operating at Extremely Low Power Consumption

A resonant tunneling diode (RTD)-based microwave on-off mode oscillator for on-off keying (OOK) transceiver applications operating at extremely low power consumption is proposed. In order to achieve the low-power operation, the negative differential conductance characteristic at a low-voltage arising from quantum effects of the RTD is used for RF signal generation. The fabricated integrated circuit of the RTD-based oscillator by using an InP-based RTD/heterojunction bipolar transistors quantum-effect IC technology shows low power consumption of 1.14 mW at an oscillation frequency of 5.725 GHz industrial, scientific, and medical band. The fabricated RTD-based oscillator operates in an on-off mode with a high data rate of 500 Mb/s. The obtained energy efficiency of 2.28 pJ/bit is found to be the best reported up to date.

A 1.52 THz RTD Triple-Push Oscillator With a

A resonant tunneling diode (RTD)-based oscillator operating at an output operation frequency of 1.52 THz is proposed. The proposed oscillator utilizes a unique negative differential conductance characteristic and a triple-push principle for high frequency operation. The RTD triple-push oscillator with an on-chip patch antenna has been successfully fabricated by using an InP-based RTD monolithic microwave integrated circuit (MMIC) technology. The fabricated RTD oscillator shows the output power of 1.9 μW at an output frequency of 1.52 THz. The obtained DC power consumption is 11.6 mW.

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This letter presents the design and fabrication of a Ku-band resonant tunneling diode (RTD)-based quadrature voltage-controlled oscillator (QVCO) with low dc power consumption and good phase noise characteristics using an InP-based RTD/HBT MMIC technology. In order to achieve a low power operation, an InP-based RTD is used for microwave quadrature signal generation based on an excellent inherent negative differential resistance (NDR) characteristic of the RTD achieved at a low applied voltage. The fabricated QVCO core shows a low dc power consumption of 1.46 mW with excellent phase noise of -121.14 dBc/Hz at a 1 MHz frequency offset. The obtained figure-of-merit (FOM) is -202.8 dBc/Hz at an oscillation frequency of 14.6 GHz, which is one of the best values among Ku-band quadrature VCOs reported up to date.

-Level Output Power

A low-power 1:2 demultiplexer (DEMUX) IC based on a resonant tunneling diode (RTD) is proposed. In order to achieve low-power consumption, the unique negative differential resistance (NDR) characteristics arising from the quantum effect of the RTD are exploited. The proposed DEMUX IC consists of an return to zero (RZ)-mode 1:2 demultiplexing block and an RZ-to-nonreturn to zero converting block, which have a compact structure based on the NDR-based circuit topologies. By implementing the proposed IC using an InP RTD/heterojunction bipolar transistor monolithic microwave integrated circuit technology, 1:2 demultiplexing operation up to 40 Gb/s has been achieved with low-power consumption of 61 mW. In addition, the result is the first demonstration of a 40-Gb/s-level current-mode-logic-type DEMUX IC based on the NDR topology.

A Novel Ku-Band RTD-Based Quadrature VCO for Low Power Applications

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 125 μW with a gain of more than 10 dB at 5.7 GHz. The amplifier performance is mainly enabled by the favorable characteristics of the 0.9-μm InP-based RTDs biased at VBIAS = 0.36 V. The RTDs exhibit a high peak-to-valley current ratio (PVCR) of 11.2 with a low peak current (IP) of 430 μA and thereby a relatively low negative resistance magnitude of 480 Ω. 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.

A Low-Power 40-Gb/s 1:2 Demultiplexer IC Based on a Resonant Tunneling Diode

An integrated resonant tunneling diode (RTD)-based 4:1 multiplexer core for low power consumption and high-speed operation is proposed. The proposed 4:1 multiplexer core is designed based on a power-efficient negative differential resistance (NDR) circuit topology, which actively utilizes the unique NDR characteristics of the RTD. The proposed IC is comprised of two RTD-based 2:1 multiplexers and a 2:1 selector. The designed IC has been fabricated using an InP RTD/heterojunction bipolar transistor (HBT) monolithic microwave integrated circuit technology, which is optimized by introducing an undercut process in the stacked RTD/HBT epistructure. A low power consumption of 75 mW at a supply voltage of -2.9 V has been achieved at a speed up to 40 Gb/s. The implemented IC, which has a higher complexity than monolithically integrated RTD/transistor digital circuits reported to date, is the first demonstration of a low-power high-speed 4:1 multiplexer IC based on an NDR device technology.

Reflection-Type RTD Low-Power Amplifier With Deep Sub-mW DC Power Consumption

This letter presents a resonant tunneling diode (RTD)-based differential oscillator topology which can enhance output power coupling for THz applications. In order to combine the differential output signals of the RTD differential oscillator, an on-chip dipole antenna is integrated into the InP-based RTD monolithic microwave integrated circuit technology. The fabricated RTD differential oscillator shows a radiated output power of 47 μW with a total dc power consumption of 14.1 mW at an oscillation frequency of 675 GHz. A high dc-to-RF efficiency of 0.33% has been obtained. This is the first implementation as an RTD differential oscillator topology for THz sources, integrated with the on-chip dipole antenna.

40 Gb/s Low-Power 4:1 Multiplexer Based on Resonant Tunneling Diodes

A low dc power RTD microwave amplifier utilizing a hybrid-coupled reflection-type topology is presented. The low-power microwave amplifier, which consists of a quadrature hybrid coupler and two RTDs, is implemented using an InP-based MMIC technology. The fabricated RTD amplifier shows low dc power consumption of 470 W with high gain of 11.5 dB at 5 GHz, resulting in high FOM of 24.5 dB/mW. The amplifier IC is the first demonstration of a low-power microwave amplifier based on the RTD device technology.

A 675 GHz Differential Oscillator Based on a Resonant Tunneling Diode

This paper describes the design and fabrication of a W-band InGaAs PIN-diode MMIC 4-bit phase shifter based on a switched delay line. In order to achieve low insertion loss and good phase shifting characteristics at W-band, the topology based on a switched delay-line is employed using a thin-film microstrip line structure. The fabricated phase shifter has demonstrated good performances such as an insertion loss less than 12.7 dB at a frequency range of 81 to 85 GHz with an intrinsic chip size of 1.93 × 0.80 mm2. To our knowledge, this is the first InGaAs PIN MMIC digital phase shifter demonstrated up to W-band.