Matsushita Electric Industrial Co., Ltd.

Kenichi Ishida

Takashi Yamamoto

Koji Sushihara

Michinori Kishimoto

Tsuyoshi Nakamura

Tomoo Kimura

Masatoshi Matsuo

Yasuo Kohashi

Hitoshi Fujimoto

Ikuo Imanishi

Tomoyuki Inomoto

Tosihiro Moriiwa

A dividing flip-flop FFis inserted in a cluster C of which the cluster length exceeds a predetermined cluster length. The flip-flop inserted cluster C is re-clustered, generating subdivided clusters Cand C. Therefore, the degree of freedom is increased in allocating clusters to a variable logic element such as an FPGA in a logical emulation device.

Logic circuit optimizing method, logic circuit optimizing device and logic circuit composing device

In the case of using a database storing therein data on a plurality of circuits which are different in parameters such as circuit scale, memory capacity, number of pins, and operating frequency, the respective parameters of the circuits are analyzed automatically and a semiconductor integrated circuit device is designed automatically in accordance with the result of the analysis such that specifications required thereof are satisfied. For processor circuits, a micro-code and the like are analyzed automatically such that the processor circuits are improved or integrated. In the case of using block function IPs containing operations and circuit elements, a database storing therein IPs in a hierarchical configuration is used and a connecting portion between the internal functions of the IPs is withdrawn to the outside of the IPs, whereby a new IP or system is constructed.

Method of designing semiconductor integrated circuit device

In a write driver circuit for switching the direction of a write current passing through a magnetic head or the like having an inductance component, an H-shaped bridge circuit is formed by using four NPN transistors in order to switch the write current at a high speed. Four switching means for controlling the base potentials of the four NPN transistors are provided and two switching means for rapidly decreasing the base potential of one of the two NPN transistors on the power source side, which is turned off when the write current passing through the magnetic head is switched are provided, thereby widening a voltage difference occurring between both terminals of the magnetic head.

Write-driver circuit

A magnetic recording device includes a magnetic disk drive for recording desired information as a magnetic signal and a reproducing signal amplifier for amplifying a small electric signal obtained by converting the magnetic signal. The reproducing signal amplifier includes an amplifier for amplifying a small electric signal supplied through an input terminal into an amplified signal having an appropriate amplitude, a central value detection circuit for detecting a central value of the AC component of the amplified signal output by the amplifier and outputting a central value signal consisting of the DC component of the amplified signal, and a subtracter for obtaining a difference between the amplified signal and the central value signal and outputting a reproducing signal.

Reproducing signal amplifier and central value signal generator

An amplifier circuit for amplifying a change in a resistance value of a magnetic resistance element is formed by connecting a first and a second current mirror circuits having the same structure in cascode, so that a voltage change is amplified without using a capacitive coupling. Hence, a high-pass filter is not created as a parasitic circuit, whereby a gain is maintained high in the low frequency region and a low frequency characteristic is excellent. Further, since control electrodes of transistors which form each current mirror circuit are grounded through the capacitance, a noise is reduced without using a conventional feedback circuit. This eliminates an influence of the feedback circuit over a high frequency characteristic, and therefore, a high frequency characteristic becomes excellent.

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Kyotanabe, Japan

Kenichi Ishida