Yi-Tsen Ku

Quadrature oscillators using two CFOAs and four passive components

Two new quadrature sinusoidal oscillators using current-feedback operational amplifiers (CFOAs) as an active building block are proposed. The proposed circuits use two CFOAs with the minimum number of passive elements, namely two resistors and two grounded capacitors. The use of only grounded capacitors makes the proposed circuits ideal for integrated circuit implementation. Both proposed circuits offer the advantages of orthogonal control of the oscillation condition and oscillation frequency, availability of two quadrature sinusoidal voltage outputs and low active and passive sensitivity performances. The HSPICE simulation and experimental results are provided to demonstrate the theoretical analysis.

A New Efficiency-Improvement Low-Ripple Charge-Pump Boost Converter Using Adaptive Slope Generator With Hysteresis Voltage Comparison Techniques

The new efficiency-improvement low-ripple charge-pump boost converter using adaptive slope generator with hysteresis voltage comparison techniques is proposed in this paper. This proposed converter can reduce output voltage ripple, because its inductor is connected to the output. This proposed converter adopts a new controlled architecture, self-adaptive slope generator with hysteresis comparison technology, to shorten the transient response. The proposed boost converter has been fabricated with TSMC 0.35-μm CMOS 2P4M processes, and a total chip area of 1.49 mm × 1.49 mm. Its maximum output current is 260 mA when the output voltage is 3.6 V. When the supply voltage is 3.3 V, the output voltage can be 3.6-5.1 V. The maximum efficiency is 90.99% and the minimum output ripple is 10.8 mV. Finally, the theoretical analysis is verified to be correct by the experimental results.

A low-voltage current conveyor using inverter-based error amplifier and its oscillator application

A low-voltage second-generation current conveyor (CCII) and its oscillator application suitable for portable systems are proposed in the paper. The proposed current conveyor is based on an inverter-based low-voltage error amplifier and a current mirror. There are no on-chip capacitors in the proposed current conveyor, and it can be designed with standard CMOS digital processes and hence will reduce the cost of chip fabrication. Moreover, the architecture of the proposed circuit without cascoded MOSFET transistors is easily designed and suitable for low-voltage operation. The CCII could be operated in a very low supply voltage such as ±0.5V. The proposed CCII has been fabricated with TSMC 0.18μm CMOS process and applied to low-voltage CCII oscillator suitable for portable systems.

A Fast Transient Response Flying-Capacitor Buck-Boost Converter Utilizing Pseudocurrent Dynamic Acceleration Techniques

A fast transient response flying-capacitor buck-boost converter is proposed to improve the efficiency of conventional switched-capacitor converters. The voltage boost ratio of the proposed converter is 2D, where D is the duty cycle of the switching signal waveform. Furthermore, the proposed structure utilizes pseudocurrent dynamic acceleration techniques to achieve fast transient response when load changes between heavy load and light load. The switching frequency of the proposed converter is 1 MHz for 3.3-V input and 1.0-4.5-V output range application. Experiment results show that the proposed scheme improves the transient response to within 2 μs and the total power conversion efficiency can be as high as 89.66%. The proposed converter has been realized by a 2P4M CMOS chip by 0.35-μm fabrication process with total chip size of about 1.5 mm × 1.5 mm, PADs included.

A Fast-Transient Boost Converter With Noise-Reduction Techniques for Wireless Sensor Networks

This paper presents a fast-transient boost converter with noise-reduction techniques for wireless sensor networks. The modulator can be directly inputted by 0.8-1.2 V for 1.8 V output. The proposed low electromagnetic interference (EMI) boost converter is based on a fast delta-sigma controller. This paper proposes a fast delta-sigma modulator for a boost converter to solve the EMI problem. The proposed converter complies with Federal Communication Commission class B conducted emission limits, in which the harmonic level must be lower than -48 dBμV for frequency from 0.45 to 30 MHz. The measured results show that the maximum efficiency of the proposed converter is 90%, and the recovery time is 4 μs from heavy to light load and 8 μs from light to heavy load. The chip was fabricated in Taiwan Semiconductor Manufacturing Co., Ltd. 1P6M 0.18-μm complementary metal-oxide-semiconductor process, and the chip area is ~0.85 mm2. It is designed to operate from 1 to 2 MHz with a 3.3-μH inductor and a 10-μF output capacitor. The proposed converter output spectrum is lower than -70 dBm or -40 dBμV.

A New Resistorless and Electronic Tunable Third-Order Quadrature Oscillator with Current and Voltage Outputs

ABSTRACT This paper presents a new resistorless and electronic tunable third-order quadrature oscillator based on voltage difference transconductance amplifiers (VDTAs). The proposed configuration using two VDTAs and three grounded capacitors has three current outputs and two voltage outputs. The resistorless circuit enjoys electronically and independently control of oscillation condition and oscillation frequency. It can simultaneously provide two quadrature output voltages, two quadrature output currents, and one amplitude-controllable output current. All the current output terminals possess high-output impedance terminals. The active and passive sensitivities of the quadrature oscillator are low. The simulation and experimental results are included to validate the theoretical analysis.

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