Ruhaifi Abdullah Zawawi

The designs of low power AC-DC converter for power electronics system applications

This paper reviews low power AC-DC converter in different techniques capable of developing high efficiency of energy consumption in many applications. By using low power AC-DC converter, the size of whole system integrated circuit could be reduced. However, the requirements of CMOS converter that required low input voltage and low voltage drop of MOS transistors is discussed. Different techniques in different application are implemented to overcome those problems. In this paper, the reviews of low power AC-DC converters have been focused for energy harvesting systems and wireless power devices only. These AC-DC converters consume several micro-watts from small ac or rf signal voltage and achieve excellent performance in terms of power efficiency. However, the power efficiency of AC-DC converter system is actually highly correlated to the relationship between voltage and the alternating current in ac source. It is because, an in-phase voltage and current in alternating current source is causing in good power factor performance. Power factor correction, PFC is important in many single-phase AC-DC converter circuits to reduce harmonic distortion, hence increase power efficiency of electric appliances. Therefore, the low power AC-DC converter with PFC is proposed. The post-layout of low power AC-DC converter is designed by using the Silterra 0.18 μm technology. The whole post-layout AC-DC converter circuit consumes only 50 μW and works in low voltage, 1V. The power efficiency of whole system also improved to 93%. The proposed low power AC-DC converter with PFC is suitable for future power electronics systems such as battery charger and energy conversion devices.

Effect of different widths in CMOS rectifier for low voltage and frequency application

This paper presents the study on the effect of different widths in CMOS rectifier for low voltage and frequency application. The model is powered by 1V peak voltage of AC supply with frequency of 50Hz. This low frequency is used in this paper to match with the supply frequency from the power plant. The design is based on the CMOS 0.18um technology. The paper focuses on the effect of the two different width sizes (4um and 50um). The result for 4um is 558.36mV and increased by 40.6% for 50um width. The simulation is run using CADENCE Simulation Tools software.

An improvement of a piecewise curvature-corrected CMOS bandgap reference

In the current paper, an improvement of piecewise curvature-corrected CMOS bandgap reference (BGR) circuit is proposed. The circuit utilizes piecewise nonlinear curvature-corrected current (PNCCC) in a conventional BGR with a current control circuit, which compensates for the voltage reference at a higher temperature range. The current control circuit (CCC) is used to reduce the total current at low temperature when the PNCCC generator is inactive. The proposed circuit is realized in CMOS 0.13µm and has been verified to be able to save power consumption by 18.6% compared with a circuit without the current control circuit.

Modeling of AC-DC converter using 0.18 μm CMOS technology

This paper proposes a modeling of low-power CMOS transistors, which are suitable for AC-DC converter applications. First section described DC analysis of input and output device of CMOS transistor using Spectre simulation tool from Cadence Design Systems. After that, advanced CMOS transistors have been applied onto development of low-voltage CMOS AC-DC converter with minimized voltage drop and power consumption. The input voltage is set to 1.0 V and the operating power supply frequency is 50 Hz. As a result, the CMOS rectifier has gained 94% of power efficiency and very small voltage drop, 39 mV with purely resistive load.

A new curvature-corrected CMOS bandgap voltage reference

The current paper presents an improved bandgap voltage reference (BGR) that utilizes curvature-corrected current generators which compensate for the voltage reference at lower and higher temperature range. The voltage reference is operated with a supply voltage of 2.5V to achieve an output reference of 1.1835V. The temperature coefficient achieved from the circuit is 1.342ppm/°C, resulting from temperature changes between -50°C to 125°C, sixfold improvement from first-order BGR. The proposed circuit is simulated using Silterra 0.13µm CMOS technology.

A New Curvature-corrected CMOS Bandgap Voltage Reference Using Current Sink Technique

This paper presents a new CMOS Bandgap Voltage Reference (BGR). The proposed circuit consists of first-order BGR and a curvature correction circuit utilizing current sink technique to compensate for the voltage reference in a wide temperature range. With a supply voltage of 2.5 V, the simulated result shows the temperature coefficient of 2.75 ppm/°C is achieved over a temperature range of -25 ° to 140 °C. The proposed circuit is realized in Silterra 0.13 μm CMOS technology.

CMOS Voltage Controlled Oscillator (VCO) with frequency stability for extended operating temperature range

In this paper, CMOS based Voltage Controlled Oscillator (VCO) with frequency stability feature was developed. Current compensation circuit design is proposed and simulated together with VCO to produce selected output frequency at approximately 27 MHz. The design was realized using Silterra 0.18um process technology. Compensation circuit was aimed to control the current level for various temperature range. Current mirror concept was adopted in the design of the compensation circuit so that it able to produce the voltage needed to maintain constant frequency generation at -25°C until 125°C temperature range. As a result, an accuracy of 10% frequency deviation obtained.

A New Pixel Readout Circuit for X-Ray Image Sensor

A new high speed Complementary Metal Oxide Semiconductor (CMOS) pixel readout circuitry consuming a small area is proposed. The whole schematic is designed using Silterra 0.18 \(\mu \)m CMOS technology and consists of 12 small-sized MOSFETs that are one-third smaller than other solutions. The time taken to capture an image of the inner body is better than that in the literature, although the same input current is used. Simulation result shows that at the minimum input current of 3 nA, the image for the three pixels at the same row can be obtained clearly at every clock cycle.

Implementation of TRL (Thru-Reflect-Line) calibration kit for power amplifier measurement

The conventional Short-Open-Load-Thru (SOLT) calibration technique and measurement problem in microwave devices are investigated in this paper. Tremendous development in mobile communication increases the demand for accuracy and performance characterizations of wireless devices over a range of frequencies. Due to this fact, simplified version of calibration technique with better features is developed in order to improve the measurements accuracy. Therefore, the work carried out in this research is to implement a simplified version of Thru-Reflect-Line (TRL) calibration standard kit that matched the requirement of the Power Amplifier(PA). The proposed technique operates in the range of frequency from 2.5Ghz to 2.57GHz in order to improve the gain of the power amplifier in real measurement environment.

A 1.6 ppm/°C bandgap voltage reference for an extended operating temperature range

A new CMOS bandgap voltage reference (BGR) is proposed and simulated using Silterra 0.13 μm CMOS technology. The proposed BGR utilizes 3 curvature-corrected current generators that compensate for the output voltage variation in an extended temperature range. The proposed circuit generates an output voltage of 1.181 V with a variation of 380 μV from !50 °C to 150 °C.