Ichirou Oota

A new approach to low ripple-noise switching converters on the basis of switched-capacitor converters

A new approach to a low ripple-noise switching converter is presented. The starting circuit is a basic switched-capacitor (SC) converter cell from which several types of low ripple-noise switching converters are generated. Two generated converters are employed for switching regulators hybridized by copper thick films on alumina substrates to realize low ripple noise. As a result, the ripple noise in the output voltages is reduced to less than 5 mVpp. Finally, this approach enables design of an ideal switching converter with zero input and output current ripple.<<ETX>>

Emergency power supply for small computer systems

A small size emergency power supply was investigated. This was realized by adopting a quick detector of momentary power failure and a compact DC-DC converter. The power failure detector has a novel type of T-V (time-voltage) conversion using an SC (switched capacitor) integrator and can detect power failures at its earliest stage. The DC-DC converter was constructed by an SC transformer in which the voltage of each stage increases according to the form of the Fibonacci sequence. The proposed power supply is supplied with power from chargeable batteries for several minutes, while the computer system saves important data to an auxiliary memory such as a disk and can complete its emergency quit operation. The circuit configurations, operations and experimental results are presented.<<ETX>>

New switched-capacitor DC-DC converter with low input current ripple and its hybridization

A switched-capacitor (SC) DC-DC converter is developed to reduce the input current ripple and to achieve miniaturization. A fixed-capacitor added to an original SC reduces the input current ripple. This converter is miniaturized by a copper thick-film hybrid technique. The features of this converter are as follows: (1) low input current ripple (one third compared with that of original SC DC-DC converters), (2) very high efficiency (90%), and (3) very high power density (23 W/in/sup 3/ in the 10 W class).<<ETX>>

Power supply for electroluminescence aiming integrated circuit

For promoting the application of electroluminescent (EL) devices, a thin-plate-typ DC-AC converter is required. For this purpose, a novel type of power supply that uses switched capacitor (SC) transformers is presented. This power supply generates on AC voltage of more than 100 V with several hundred hertz by using two types of SC transformers. This scheme has the following advantages: (1) it operates on a low battery voltage, (2) it realizes a very large transformer ratio, (3) it is capable of realization in an IC form as a thin plate type power supply that is capable of being unified onto the back of an EL device, and (4) it generates a sinusoidal voltage in a novel way by selection of voltages. The circuit configurations, operations, and basic experimental results are presented.<<ETX>>

A general method for deriving output resistances of serial fixed type switched-capacitor power supplies

A simple method for deriving analytically the output resistance of switched-capacitor (SC) power supplies is presented. By using the proposed method, the output resistances of the serial fixed type SC transformers are derived as a general case. The obtained output resistances are exactly equal to those using the conventional method.

Realization of a switched-capacitor AC-DC converter using a new phase controller

A new phase controller for a switched-capacitor (SC) AC-DC converter is presented. The features of this circuit are as follows. (1) The efficiency of the SC AC-DC converter regulated by the proposed phase controller is high compared with that regulated by a pulse-width-modulated (PWM) controller, especially when the input voltage increases. (2) The operating ranges of the input voltage and of the output current can be wider than the converter using a PWM controller. (3) The inrush current of the SC AC-DC converter can be easily limited to a desired value by the phase controller without producing any extra loss. (4) The operating frequency of the phase controller covers almost all commercial frequency ranges, from several tens of Hz to several hundred Hz, without any adjustment. (5) Even when the number of the clocks increases, the phase controller requires only one additional D flip flop for every added clock. These features were confirmed by experiments.<<ETX>>

Programmable ring type switched-capacitor DC-DC converters

New dc–dc converters are presented whose step-up and step-down ratio can be controlled easily by changing their external clocks. These converters consist of switched capacitors that form a ring connected by MOSFET switches (“ring-type SC”). The proposed circuits have the following features: (1) Their step-up and step-down ratios can be controlled programmably by changing the patterns of clocks because of their symmetry structure. (2) They can treat a wide input voltage range from low voltage to high voltage without changing their structures. (3) Various output voltages can be supplied by using DIP-switches or a computer control. (4) They can contribute to lower the costs of production, since they correspond to various input and output voltages with the same circuit. (5) A soft start circuit of the control apparatus can be easily realized. (6) They can be implemented in one-chip IC form together with other signal processing circuits such as a system-on-chip or a system integration including power supplies, since generation of a magnetic field is extremely low due to the coilless construction.

A ring type switched-capacitor (SC) programmable converter with DC or AC input/DC or AC output

We have already proposed a ring type switched-capacitor (SC) converter. This converter consists of capacitors which make a ring connection switches. In this paper, we propose programmable converter of DC-DC, DC-AC, AC-DC and AC-AC using a ring type SC converter. The SPICE simulations show that the power efficiency is more than 80%. This converter can provide to some combination of DC or AC input/DC or AC output.

Design and realization of a switched-capacitor AC-DC converter with a low output-voltage ripple

An AC-DC converter using a new switched-capacitor (SC) transformer and its design are presented. The maximum voltage of capacitors is 1/n times that of a capacitor- input-type rectifier circuit, where n is the number of charge-transfer capacitors. The output voltage ripple is small, since the equivalent smoothing capacitor value is n times that of conventional SC transformers (series-parallel switching type). Using the design method presented, a test circuit was designed. The experimental results of the test circuit show that the efficiency of the SC transformer is very high (95%) and the maximum output power is 40 W.<<ETX>>

A new ring type switched-capacitor DC-DC converter with low inrush current and low ripple

A new switched-capacitor(SC) DC-DC converter is presented. This converter consists of n ring-shaped capacitors connected by switches. The converter has the following features as compared with conventional SC converters: (1) since only one capacitor is charged at one time, the inrush current and the input current ripple are small; (2) the converter has a smaller number of switches; (3) all floating switches form totem-pole connections with grounded switches, thus driving them is easy; and (4) since the generation of the magnetic field is few, together with some signal processing circuits, it is possible to be implemented in one chip IC form such as a system-on-chip.