Jongchan Choi

Design of 250-Mb/s Low-Power Fiber Optic Transmitter and Receiver ICs for POF Applications

This paper describes 250-Mb/s fiber optic transmitter and receiver ICs for plastic optical fiber applications using a 0.18-μm CMOS technology. Simple signal and light detection schemes are introduced for power reduction in sleep mode. The transmitter converts non-return-to-zero digital data into 650-nm visible-red light signal and the receiver recovers the digital data from the incident light signal through up to 50-m plastic optical fiber. The transmitter and receiver ICs occupy only 0.62 mm 2 of area including electrostatic discharge protection diodes and bonding pads. The transmitter IC consumes 23 mA with 20 mA of LED driving currents, and the receiver IC consumes 16 mA with 4 mA of output driving currents at 250 Mb/s of data rate from a 3.3-V supply in active mode. In sleep mode, the transmitter and receiver ICs consume only 25 μA and 40 μA, respectively.

iVision based Context-Aware Smart Home system

Ultimate goal of ubiquitous computing is to move computers away from the users focus, by embedding them into the environment. The user will be surrounded by smart and internet powered devices. In this work we describe our research about the Smart Home system. Our solution contains all sorts of smart entities necessary at home. For the interaction with the user we defined two outputs: Smart Wall and Smart TV, and one input: iVision. iVision system is designed and implemented on SoC (System on Chip), to get higher performance, and less latency. Smart home appliances are implemented based on DPWS (Device Profile for Web Services). Additionally Context-Awareness driven architecture was suggested, to improve the quality of the service in a Smart Home system.

Two Hand Gesture Recognition Using Stereo Camera

This paper proposes method for gesture recognition by two hands. In this research stereo camera was used to calculate depth map of the frame. Based on depth information precise tracking of the hands was applied. Depth map calculates in hardware level. Oversensitivity of camera to light generates horizontal noise. Especially appeared horizontal noise affects on tracking two hands located in same altitude. In this paper we suggest masking method to avoid horizontal noise in software level.

A 1Gb/s Optical Transceiver Array Chipset for Automotive Wired Interconnects

A 4-channel 1Gb/s optical transceiver chipset is realized in a 0.18-mum standard CMOS technology for the wired networks in automotive vehicles. The transmitter (LD driver) operates for 1-Gb/s LVDS/CML signals with AMC and APC loops. The output optical eye-diagrams demonstrate 0.2UI jitter characteristics with max. 80mApp modulation currents for 1-Gb/s 211

Intelligent modified channel and frequency offset estimation schemes in future generation OFDM-based packet communication systems

1 input PRBS. Meanwhile, the receiver (TIA) demonstrates 76.6dBOmega transimpedance gain, 724MHz bandwidth for 6pF input capacitance, -18dBm optical sensitivity for BER of 10-12, and 90mW power dissipation from a single 3.3V power supply

Unequal Preamble Power Allocation Scheme for Frequency Offset Estimation in OFDM Based Packet Communication Systems

The channel estimation and frequency offset estimation scheme for future generation orthogonal frequency division multiplexing (OFDM-) based intelligent packet communication systems are proposed. In the channel estimation scheme, we use additional 8 short training symbols besides 2 long training symbols for intelligently improving estimation performance. In the proposed frequency offset estimation scheme, we allocate intelligently different powers to the short and long training symbols while maintaining average power of overall preamble sequence. The preamble structure considered is based on the preamble specified in standardization group of IEEE802.11a for wireless local area network (WLAN) and IEEE802.11p for intelligent transportation systems (ITSs). From the simulation results, it is shown that the proposed intelligent estimation schemes can achieve better mean squared error (MSE) performance for channel and frequency offset estimation error than the conventional scheme. The proposed schemes can be used in designing for enhancing the performance of OFDM-based future generation intelligent communication network systems.

Design of a 12-Channel 120-Gbs Optical Receiver Array in 0.18-µm CMOS Technology

In this paper, an frequency offset estimation scheme for orthogonal frequency division multiplexing (OFDM) based packet communication systems is proposed, in which allocated powers of the short training symbols and long training symbols are different while maintaining average power of overall preamble sequence. The preamble structure considered is based on the preamble specified in IEEE802.11a and IEEE802.11p standardization group. From the simulation results, it is shown that the proposed scheme can achieve better mean squared error (MSE) performance for frequency offset estimation error than the conventional scheme.

A 1Gb/s 4-Channel Optical Transceiver Chipset for Automotive Wired Networks

In this work, a 12-channel 120-Gb/s optical receiver array is realized in a 0.18-mum CMOS process. Optical receiver array consists of transimpedance amplifier (TIA) and limiting amplifier (LA). To enhance the bandwidth without deterioration of the other performance, advanced common-gate input configuration, active feedback technique, and negative impedance compensation are exploited. Post-layout simulations demonstrate that a single channel optical receiver achieves 96-dBOmega transimpedance gain (ZT), 10-Gb/s operations with 7.1- GHz bandwidth for 0.5-pF photodiode capacitance, and -20-dBm optical sensitivity.

Embedded wireless LAN base-band processor for ubiquitous computing systems

A 4-channel optical transceiver chipset is designed in a 0.18 mum standard CMOS technology for the applications of automotive wired networks. The transmitter LD driver operate at 1 Gb/s with reliable APC (30-70 mA) and AMC (20-80 mApp) controls, whereas the receiver TIA demonstrates 76.6 dBOmega transimpedance gain and 724 MHz bandwidth against the very large input parasitic capacitance (6 pF) with 40 mW power dissipation from a single 3.3 V supply.

A 110 dB, 3-mW fourth-order Σ-Δ modulator for atmospheric pressure sensor

We propose a ubiquitous computing processor, which contains an IEEE802.11b wireless LAN for a communication channel. The IEEE802.11b wireless LAN would play an important role in the first generation of ubiquitous computing systems. In this work, the hardwired IEEE802.11b wireless LAN base-band processor, which supports the AMBA interface, was implemented and verified within a verification environment. As a result of this verification, we demonstrated that the implemented wireless baseband processor supports the IEEE802.11b standard. Also, it shows that the IEEE802.11b wireless LAN could play the role of the basic download channel in the proposed ubiquitous processor.