Dong-Shiuh Wu

Learning feedback controller design of switching converters via MATLAB/SIMULINK

The application of MATLAB/SIMULINK is developed for simulation and learning feedback controller design of DC-DC switching converters. With the help of its intuitive graphical user interface and some basic circuit theories, the corresponding SIMULINK models of the switching converter circuits can be easily constructed. Students can then use these models to learn and evaluate the closed-loop behavior of the entire system in the MATLAB/SIMULINK environment, after feedback controllers are devised by any classical or modern control theory. The accuracy of this approach is also verified by comparing the simulation results with the responses obtained from a buck-type DC-DC switching converter circuit and existing experimental results.

Multiphase sinusoidal oscillator using second-generation current conveyors

Abstract A multiphase sinusoidal oscillator using second-generation current conveyors is presented. The oscillator can generate n signals which are equal in amplitude and equally spaced in phase. The oscillation frequency of each phase is independently controlled by a grounded resistor, which makes it easy to convert into a voltage-controlled multiphase oscillator. The proposed circuit is suitable for IC fabrication because all the passive elements are grounded. Experimental results are given to verify the theoretical analysis.

Sinusoidal oscillators with single element control using a current-feedback amplifier

New sinusoidal oscillators with single element control using a current-feedback amplifier (CFA) are presented. The oscillation frequency of the proposed sinusoidal oscillators can be controlled by a resistor or capacitor. The oscillation frequency of one of the proposed sinusoidal oscillators is insensitive to the input and output voltage tracking errors of the CFA. Another of the proposed oscillators uses only grounded capacitors. Passive and active sensitivities are all low. Experimental results that confirm the theoretical analysis are obtained.

Active-R sinusoidal oscillators using the CFA pole

Three new sinusoidal oscillators using ihe curreni feedback amplifier (CFA) pole are presented. Two of the proposed sinusoidal oscillators consist of CFAs and resistors without external capacitances. Their oscillation condition and frequency can be independently controlled by two resistors. Experimental results were given lo demonstrate the feasibility of the proposed circuits. The proposed circuits will be suitable for high-frequency applications and integration in bipolar monolithic lechnology.

CFA-based universal filter deduced from a Mason graph

A current feedback amplifier (CFA)-based universal filter deduced from a Mason graph is presented. The filter has the following merits: it only uses two CFAs and five passive elements, needless of any matching condition, it offers a bulfered output, and has low passive and active sensitivities. Experimental results, which agree very well with the theoretical result, are also obtained.

A Low Dropout regulator using current buffer compensation technique

A current buffer compensation Low Dropout (LDO) regulator for portable applications is present in this paper. The current buffer compensation scheme is a current feedback amplifier, which provides low output impendence in order to move the non-dominant pole due to the large gate capacitance of the pass transistor of the LDO regulator to high frequency. This LDO circuit had been designed and implemented in a 0.35-µm CMOS processes, it occupied a chip area of 810×572 µm2. The measurement results show that this circuit functions properly with supply voltage of 2.2∼3.3 V and provides maximum current of 200 mA. The output voltage can be adjusted from 0.6 V to 3.1 V when the supply voltage is 3.3 V.

A monolithic buck DC-DC converter with on-chip PWM circuit

A monolithic CMOS voltage-mode, buck DC-DC converter with integrated power switches and new on-chip pulse-width modulation (PWM) technique of switching control is presented in this paper. The PWM scheme is constructed by a CMOS ring oscillator, which duty is compensated by a pseudo hyperbola curve current generator to achieve almost constant frequency operation. The minimum operating voltage of this voltage-mode buck DC-DC converter is 1.2V. The proposed buck DC-DC converter with a chip area of 0.82mm^2 is fabricated with a standard 0.35-@mm CMOS process. The experimental results show that the converter is well regulated over an output range from 0.3 to 1.2V, with an input voltage of 1.5V. The maximum efficiency of the converter is 88%, and its efficiency is kept above 80% over an output power ranging from 30 to 300mW.

New CMOS inverter-based voltage multipliers

Four new CMOS inverter-based voltage multipliers consisted of PMOS/NMOS pass transistors, inverter circuits, and capacitors are proposed in the paper. The proposed voltage multipliers which combine the functions of rectifiers and charge-pumps improve the power conversion efficiency and reduce the number of passive components therefore they are suitable for the integration. The voltage multiplier with positive output voltage is implemented with TSMC 0.35µm CMOS 2P4M processes, and the experimental results have showed good agreement with the theoretical analysis. The chip area without pads is only 1.75×1.32 mm2 for five-stage positive output voltage of voltage multiplier

Linear transformation all-pole filters based on current conveyors

Abstract A method for the synthesis of doubly terminated lossless ladder filters employing second-generation current conveyors (CCIIs) (Sedra and Smith 1970) is presented. This technique is realized via the linear transformation (LT) (Dimopoulos and Constantinides 1978, Hwang et al. 1994), and it is suitable for high-order filter design. We propose a systematic design method to realize CCII-based filters efficiently. A design example using minimum number of CCIIs and only grounded capacitors is described for the third-order Chebychev lowpass filter. Experimental results that confirm the theoretical analysis are obtained.

A PLL-based current-mode PWM circuit suitable for current-mode controlled techniques

A wide-range current-mode pulse-width modulation circuit for current-mode controlled techniques is presented in this paper. The proposed circuit has been designed and implemented using 0.35-¿m CMOS 2P4M process. The core die size is around 95×115 ¿m2 . The experimental results show that the variation of the output frequency within ±0.25%. The linear range of input current is from 114 to 297 ¿A , and corresponding duty cycle of pulse-width output is from 2.5% to 93.5%.