Tae-Won Ahn

A /spl Sigma/-/spl Delta/ fractional-N frequency synthesizer using a wide-band integrated VCO and a fast AFC technique for GSM/GPRS/WCDMA applications

A fractional-N frequency synthesizer (FNFS) in a 0.5-/spl mu/m SiGe BiCMOS technology is implemented. In order to operate in a wide-band frequency range, a switched-capacitors bank LC tank voltage-controlled oscillator (VCO) and an adaptive frequency calibration (AFC) technique are used. The measured VCO tuning range is as wide as 600 MHz (40%) from 1.15 to 1.75 GHz with a tuning sensitivity from 5.2 to 17.5 MHz/V. A 3-bit fourth-order /spl Sigma/-/spl Delta/ modulator is used to reduce out-of-band phase noise and to meet a frequency resolution of less than 3 Hz as well as agile switching time. The experimental results show -80 dBc/Hz in-band phase noise within the loop bandwidth of 25 kHz and -129 dBc/Hz out-of-band phase noise at 400-kHz offset frequency. The fractional spurious is less than -70 dBc/Hz at 300-kHz offset frequency and the reference spur is -75 dBc/Hz. The lock time is less than 150 /spl mu/s. The proposed synthesizer consumes 19.5 mA from a single 2.8-V supply voltage and meets the requirements of GSM/GPRS/WCDMA applications.

R-URC: RF4CE-Based Universal Remote Control Framework Using Smartphone

RC (Remote Control) is a technology that can efficiently control and transfer a variety of user commands to CEs (Consumer Electronics). However, the existing RCs have been required various additional features such as communication between CEs, extension of communication range, low power-consumption and bi-directional communication according to the advent of new types of CE devices and its enhanced performance. Even though RC controller has many customers’ requests, it is not a simple solution because most legacies work on IR-based RC. In this paper, we propose RF4CE-based Universal Remote Control Framework using Smartphone in order to solve the many constraints of IR legacies. The proposed R-URC system is designed by RF4CE platform which is a kind of de-facto standard for CE remote control communication. From the verification scenarios using various CEs and smart phone, we can see that the proposed R-URC shows the good practical usage in terms of contents sharing and smart CE control.

A /spl Sigma/-/spl Delta/ fractional-N frequency synthesizer using a wideband integrated VCO and a fast AFC technique for GSM/GPRS/WCDMA applications

A fractional-N frequency synthesizer (FNFS) in a 0.5-/spl mu/m SiGe BiCMOS technology is implemented. In order to operate wideband frequency range, a switched capacitor bank LC tank VCO and an adaptive frequency calibration (AFC) technique are used. A 3-bit 4th order /spl Sigma/-/spl Delta/ modulator is used to reduce out-of-band phase noise and to meet a frequency resolution of less than 3Hz as well as agile switching time. The experimental results show -80dBc/Hz in-band phase noise within the loop bandwidth of 25 kHz and -129dBc/Hz out-of-band phase noise at 400kHz-offset frequency. The fractional spurious is less than -70dBc/Hz at 300kHz offset frequency and the reference spur is -75dBc/Hz. The lock time is less than 150 /spl mu/s. The proposed synthesizer consumes 19.5 mA from a single 2.8-V supply voltage and meets the requirements of GSM/GPRS/WCDMA applications.

A 2.6 V GSM/PCN dual band variable gain low noise RF down conversion mixer

As a building block for a GSM/PCN dual band RF transceiver IC, a low noise variable gain RF down conversion mixer is designed and fabricated using a 15 GHz-f/sub T/, 0.5 /spl mu/m 3-metal 2-poly BiCMOS process. Careful consideration is paid to the low noise performance of the mixer. Moreover, using constant-impedance input/output stages, RF input and IF output return losses are maintained under -16 dB for both high and low gain modes. Measured gain and DSB noise figure of the mixer are 10.9 dB and 9.1 dB, respectively, for GSM band, and 9.6 dB and 8.1 dB, respectively, for PCN band. Gain difference between high and low gain modes is 11 dB and 11.8 dB for GSM and PCN, respectively. Total DC currents are 13 mA for GSM and 11.5 mA for PCN from a 3 V supply voltage. Mixer performance is maintained with supply voltage down to 2.6 V.

Design and Implementation of an Easy-Setup Framework for Personalized Cloud Device

With the popularization of Public Cloud services, requirements for Personal Cloud services with more enhanced security and independent personalized storage are also increasing. In order to provide Personal Cloud services, a variety of Home Cloud devices available in the home have been introduced. Based on the analysis of these devices and previous researches, we extracted critical restrictions regarding the initial configuration such as the complex procedures, limitation of installation environment, and the problem that users wasted a lot of time for its setup. Thus, we propose a novel wireless network-based Easy-Setup framework using smartphones and Android-based personal cloud devices-HomeSync in order to improve these restrictions. In addition, we constructed an experiment test-bed to validate the effectiveness of our proposed framework. Finally, we present the results of the comparative experiments compared with previous researches in terms of consumption time and initial setup procedures.