Kyung-Hoon Yang

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 poly

Memristor devices based on electrochemical metallization operate through electrochemical formation/dissolution of nanoscale metallic filaments, and they are considered a promising future nonvolatile memory because of their outstanding characteristics over conventional charge-based memories. However, nanoscale conductive paths or filaments precipitated from the redox process of metallic elements are randomly formed inside oxides, resulting in unexpected and stochastic memristive switching paramet

High-speed, long-wavelength InAlAs/InGaAs OEIC photoreceivers based on a p-i-n/HBT shared layer integration scheme have been designed, fabricated and characterized. The p-i-n photodiodes, formed with the 6000 /spl Aring/-thick InGaAs precollector layer of the HBT as the absorbing layer, exhibited a responsivity of /spl sim/0.4 A/W and a -3 dB optical bandwidth larger than 20 GHz at /spl lambda/=1.55 /spl mu/m. The fabricated three-stage transimpedance amplifier with a feedback resistor of 550 /s

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A new scheme for power amplifiers is proposed, which can provide both high efficiency and linearity. The proposed amplifier operates in a virtual class-A mode under dual-bias control to maximize the power-added efficiency along with its inherent class-A linearity. The dynamic dual-bias control involves controlling both bias current and voltage of the amplifier with a varying envelope of input RF signals. The efficiency of the proposed amplifier is theoretically evaluated and compared with that o

The design and performance of a Ka-band 5 b MMIC phase shifter using InGaAs PIN switching diodes is presented. In order to achieve low insertion loss and good phase shifting characteristics at Ka-band, a switched reactance type InGaAs PIN-diode phase shifter topology has been employed with a compact bias network. The fabricated InGaAs PIN MMIC phase shifter has demonstrated good performance characteristics such as a low insertion loss of less than 7.8 dB and a high P <sub xmlns:mml="http://www.w

This letter describes the design and fabrication of a high-linearity GaN PIN MMIC switch. In order to achieve good input/output matching and high-linearity characteristics at the K-band, a GaN PIN-diode-based switch was employed with an absorptive-type topology. The fabricated GaN PIN MMIC switch demonstrated good performance characteristics such as input/output return losses of higher than 10.5 dB and a high IIP <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/

The DC characteristics of InP-InGaAs and InAlAs-InGaAs HBT's with abrupt emitter-base junctions are studied using a thermionic-field emission boundary-condition model. The model incorporates tunneling and thermionic emission into a one-dimensional drift-diffusion numerical scheme and accounts for breakdown and bulk recombination mechanisms. The effects of abrupt heterojunction transport and electrical junction displacement on the current gain h/sub FE/ and on the turn-on voltage are investigated

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 o

The injection performance of abrupt emitter HBT's and related effects on the device characteristics are studied by taking an Npn Al/sub 0.25/Ga/sub 0.75/As/GaAs/GaAs HBT as an example. In order to take into account the coupled transport phenomena of drift-diffusion and tunneling-emission processes across the abrupt heterojunction in a single coupled formulation, a numerical technique based on the boundary condition approach is employed. Compared to previous numerical investigations relying on ei

This letter presents the design and fabrication of a Ku-band differential-mode voltage-controlled oscillator (VCO) with extremely low power consumption and good phase noise characteristics based on a monolithic InP-based resonant tunneling diode/heterojunction bipolar transistor (RTD)/(HBT) technology. In order to reduce the power consumption, an InP-based RTD is used for microwave power generation, which shows the negative resistance characteristics at a low voltage. The fabricated VCO shows an

An HBT model for InP-based single HBTs (SHBTs) was developed based on the conventional Gummel-Poon large-signal BJT model available in HSPICE. Several typical characteristics observed from InP-based SHBTs, such as soft breakdown and collector transit-time delay effects, were modeled through a macro modeling approach. Excellent agreement has been achieved between the experimental and calculated results based on the model.

A new scheme for power amplifiers is proposed, which can provide both high efficiency and linearity. The proposed amplifier operates in a virtual Class-A mode under novel dual bias control to maximize the power-added efficiency along with its inherent Class-A linearity. The new dynamic dual bias control involves controlling both bias current and voltage of the amplifier with a varying envelope of input RF signals. The efficiency of the proposed amplifier is theoretically evaluated and compared w