Wonseok Oh

Current feedback amplifiers (CFAs) provide fast response and high slew rate with Class-AB operation. Fast response, low-dropout regulators (LDRs) are critical for supply regulation of deep-submicron analog baseband and RF system-on-chip designs. An LDR with an CFA-based second stage driving the regulation field-effect transistor is presented. The low dropout (LDO) achieves an output noise spectral density of 67.7 nV radicHz, and PSR of 38 dB, both at 100 kHz. In comparison to an equivalent power

Low 1/ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> noise, low-dropout (LDO) regulators are becoming critical for the supply regulation of deep-submicron analog baseband and RF system-on-chip designs. A low-noise, high accuracy LDO regulator (LN-LDO) utilizing a chopper stabilized error amplifier is presented. In order to achieve fast response during load transients, a current-mode feedback amplifier (CFA) is designed as a second stage drivin

The fuzzy logic controller has been focused in the field of vector control of induction motors. However, a systematic method for designing and tuning the fuzzy logic controller is not developed yet. In this paper, an auto-tuning method for fuzzy logic controller based on the genetic algorithm is presented. In the proposed method, normalization parameters and membership function parameters of a fuzzy controller are translated into binary bit-strings, which are processed by the genetic algorithm i

A new three phase three-level pulsewidth modulation (PWM) switched voltage source inverter with zero neutral point potential is proposed. It consists of three single-phase inverter modules and each module is composed of a switched voltage source and inverter switches. The major advantage is that the peak value of the phase output voltage is twice as high as that of the conventional neutral-point-clamped PWM inverter. Thus, the proposed inverter is suitable for applications with low voltage sourc

We present PyTER, an automated program repair (APR) technique for Python type errors. Python developers struggle with type error exceptions that are prevalent and difficult to fix. Despite the importance, however, automatically repairing type errors in dynamically typed languages such as Python has received little attention in the APR community and no existing techniques are readily available for practical use. PyTER is the first technique that is carefully designed to fix diverse type errors in

Low-noise, low-dropout (LN-LDO) regulators are critical for supply regulation of deep-submicron analog baseband and RF system-on-chip designs. A low 1/f noise LDO regulator utilizing a chopper stabilized error amplifier is presented. In order to achieve fast response during load transients, a current-mode feedback amplifier (CFA) with an asymmetrical input pair is designed as a second stage. With chopping frequencies up to 1MHz, an output noise spectral density of 32nV/radicHz and PSR of 38dB is

For the high performance drives of induction motor, recurrent artificial neural network (RNN) based self tuning speed controller is proposed. RNN provides a nonlinear modeling of motor drive system and could give the information of the load variation, system noise and parameter variation of induction motor to the controller through the on-line estimated weights of corresponding RNN. Self tuning controller can change gains of the controller according to system conditions. The gains are composed o

In this paper, a 4-channel 10-Gb/s VCSEL driver array with adaptive optical power control is implemented using 0.13-µm CMOS technology. The proposed VCSEL driver compensates temperature effects of VCSEL using auto-power control (APC) and auto-modulation control (AMC). External monitoring photodiode (MPD) helps the detection of optical power and modulation. The proposed APC and AMC demonstrates 5∼20-mA of bias-current control and 5∼20-mA of modulation-current control, respectively. To enhance the

A 4-channel CMOS VCSEL driver array is implemented in 0.13-mum CMOS technology. The optical transmitter drives VCSEL array, operating up to 10-Gb/s with APC (5-20-mA) and AMC (5-15-mApp) loops to obtain constant and reliable optical output power. To enhance the bandwidth of the pre-amplifier, active feedback technique with negative impedance compensation (NIC) is exploited. A single channel VCSEL driver achieves 12-dB voltage gain, 10-Gb/s operations with 8.5-GHz bandwidth for 0.2-pF VCSEL capac

Low-noise, low-dropout (LN-LDO) regulators are critical for supply regulation of deep-submicron analog baseband and RF system-on-chip designs. A low 1/f noise LDO regulator utilizing a chopper stabilized error amplifier is introduced. A secondary amplifier with supply ripple subtraction stage is used for PSR improvement. With the proposed techniques, less than 180 nV/radicHz output noise spectral density and 50 dB of PSR is measured at 10 kHz frequency. With chopping frequencies up to 1MHz, the

This paper presents an automatic AC source transfer switch for broadcasting and communication equipment. Since the proposed transfer switch has a short transfer time under 4[msec], system power reset is prevented when the main source has a trouble as like a black-out. Although the proposed source transfer switch adopts relay as a switching device, the transfer time is under 500t[μsec] when the main source is recovered, under voltage status, and overvoltage status. Moreover zero current switching

In this paper, a 12.5-Gb/s optical transmitter is implemented using 0.13-<TEX>${\mu}m$</TEX> CMOS technology. The optical transmitter that we constructed compensates temperature effects of VCSEL (Vertical cavity surface emitting laser) using auto-power control (APC) and auto-modulation control (AMC). An external monitoring photodiode (MPD) detects optical power and modulation. The proposed APC and AMC demonstrate 5<TEX>$\sim$</TEX>20-mA of bias-current control and 5<TEX>$\sim$</TEX>20-mA of modu

This study presents a technique of measuring the fiiction losses of a compressor. The basic idea is that the kinetic energy of compressor mechanism is dissipated by the fiiction when compressor is turned off. So, the viscous fiiction losses can be calculated from measured acceleration. This method has the advantage that losses of a compressor are measured by placing the accelerometer on proper position of compressor without modifying the shaft or another parts of compressor. INTRODUCTION Estimat