Jeong-won Lee

Initial direction and speed decision system for auto focus based on blur detection

This paper proposes a new algorithm for deciding the starting lens focus direction and speed in aid of contrast autofocus using only one initial image with blur detection. Simulation results show that the fundamental idea could support contrast auto-focus in reducing operation time by deciding appropriate starting direction in some certain circumstances.

Maximum likelihood decoding of the partial response signal with analog parallel processing circuits of the CNN

The partial response maximum likelihood (PRML) decoder is designed with the analog parallel processing circuits of the CNN. The PR technology is incorporated with the multi-level coding and normally used for the high density magnetic storage device or DVD. The technology combined with the optimization is called PRML and used for error correction of the storage device. Being required lots of computation in the PRML, the parallel processing structure with the CNNs massive connections is able to be an efficient solution. In this study, a decoder for the PR signal called PR(1 2 2 1) is designed with the analog parallel circuits of the CNN. The circuits are connected circularly, which enables to decode the symbols continually. On-trellis circuit decoding enables faster decoding. The circuit simulations show that the power consumption of the proposed one is 1/3 and its silicon area is 1/2 of the digital Viterbi decoder to achieve the similar error correction performance.

High speed mixed analog/digital PRML architecture for optical data storage system

New mixed analog/digital PRML (partial response maximum likelihood) architecture for the optical drive system is presented. In order to realize high speed, low power and low cost solution, new data and clock recovery circuits are proposed. The proposed architecture is based on the efficient combination of digital and analog circuits to provide high speed and low power data detection for optical data storage system. The presented circuit shows increased operating speed by 67%, reduced power consumption by 28% and area by 42%, therefore it provides high speed, low power and low cost SOC solution for the future optical drive system. A test chip produced is fabricated using 0.18 /spl mu/m CMOS technology and the product has been proved to demonstrate the performance of the proposed architecture.

An improved architecture of the mixed mode clock/data recovery for DVD read channel

A mixed mode clock and data recovery module for DVD player and recorder is developed. The proposed system is the improved version of the conventional one which integrates an analog front end, a clock recovery circuit, and a partial response maximum likelihood (PRML) employing PR (1,2,2,1) channel model. For achieving a low-power, low-cost and high speed read-channel IC, the digital adaptive equalizer in the conventional DVD system is replaced with a waveform controller. Also, an analog charge-pump and external low pass filter (LPF) are employed instead of the digital LPF in the clock recovery loop for higher speed. The proposed architecture reduces power consumption and die size by 28.3% and 41.8%, respectively. Gain with the PRML technique is about 4 dB superior to that of a slicer at BER 10/sup -4/. The chip has been fabricated with 0.18 /spl mu/m one-poly five-metal CMOS technology.

Simulation of transmission lines with frequency dependent losses by indirect numerical integration

This paper presents the time domain simulation of multiple coupled transmission lines with frequency dependent conductor (skin effect) and dielectric losses by an indirect numerical integration method. The method is based on an analytical relationship between the continuous and discrete domains, and allows one to recurrently calculate in the time domain a transient response of arbitrary dynamic systems, including time-varying, frequency-dependent, and nonlinear ones. Also, the paper describes the implementation of multiconductor, coupled lines with frequency dependent losses in SPICE3f4. This implementation ties SPICE transient analysis of a transmission line and is more efficient than another approach based on the concept of the numerical Laplace, Fourier transformations and convolution.