Fumio Ueno

Fuzzy multiple-input maximum and minimum circuits in current mode and their analyses using bounded-difference equations

Multiple-input maximum and minimum circuits in current mode are proposed. The operation of these circuits is formulated using simultaneous bounded-difference equations. The exact analyses are performed by solving the bounded-difference equations. The accuracy of these circuits is better than the accuracy of binary tree realizations using two-input max/min circuits because no accumulation of errors occurs; furthermore, the operation speed is higher than the speed of the binary tree realization. The proposed circuits consist of only MOS transistors and are compatible with standard MOS fabrication processes. These circuits are useful building blocks for a real-time fuzzy controller and a fuzzy computer. >

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>>

Current-mode analog fuzzy hardware with voltage input interface and normalization locked loop

A voltage-input current-output membership function circuit (MFC) and a normalization locked loop (NLL) are proposed. They are useful building blocks for current-mode analog fuzzy hardware. The voltage-input current-output MFC consists of two-source-coupled-type operational transconductance amplifiers (OTAs). The MFC is used in the input parts of the analog fuzzy hardware system. The fuzzy hardware system can execute the singleton fuzzy control algorithm. In the algorithm, the weighted average operation is processed. When the weighted average operation is directly realized by analog circuits, a divider must be implemented. The NLL circuit, which can process the weighted average operation without the divider, is implemented using a one-source-coupled OTA. The proposed circuits were designed by using 2- mu m CMOS design rules and their operations were confirmed using SPICE simulations.<<ETX>>

7.5 MFLIPS fuzzy microprocessor using SIMD and logic-in-memory structure

Two fuzzy microprocessors have been developed as VLSI chips. One is an if-part processor with single instruction, multiple data (SIMD) architecture, and the other is a then-part processor with logic-in-memory. The system configuration using the chips can execute fuzzy inference for if-then fuzzy rules. The speed of inference including defuzzification is 7.5 M fuzzy logical inferences per second (FLIPS), and the system can process 960 rules and 16 input and output variables. The rule format can be easily changed by rewriting the instructions stored in the memory. The processors require no external memory since the knowledge-base can be stored in the internal memory.<<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>>

Regulation of Cuk converters using fuzzy controllers

Synthesis of a control system using a fuzzy inference is proposed for switching regulators. A computer simulation result is given, as an example, where an output voltage of a Cuk converter is regulated by using the proposed fuzzy inference. The simulated waveforms of the output voltage at start-up and the responses to disturbances (variations of the load resistance and of the input voltage) are studied, as compared with those of a conventional proportional integral derivative (PID) control. The variation of the output voltage is smaller and the output voltage settles faster than that using the PID control.<<ETX>>

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>>

A design of current-mode analog circuits for fuzzy inference hardware systems

Current-mode analog circuits, i.e., a maximum (MAX) circuit, a minimum (MIN) circuit, and a defuzzified circuit, for fuzzy inference hardware systems, are proposed. The design of the proposed MAX and MIN circuits is based on simple bounded-difference equations. The defuzzifier circuit is synthesized using multipliers/dividers based on the translinear principle. The design considerations and the simulation results of a 2 /spl times/ 2 fuzzy controller using the proposed circuits are described.<<ETX>>

A fuzzy logic function generator (FLUG) implemented with current mode CMOS circuits

A fuzzy logic function generator (FLUG) based on the singleton fuzzy control algorithm is proposed. The normalizing operation can be removed from the original algorithm by introducing a new t-norm operation. The FLUG can be simply implemented with the current mode CMOS circuits, because the dividers are not needed. Further, to solve the problem in the current mode with respect to the restriction of the fan-out number, voltage-input, and current-output membership function circuits are constituted of operational transconductance amplifiers (OTAs), and they are used in the input parts of the FLUG. Due to the simple circuitry, the FLUG can be applied to a basic cell for the analog application-specific ICs.<<ETX>>