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[Author] Masahiro IWAMURA(2hit)

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  • Design of the Basic Cell and Metallized RAM for 0.5 µm CMOS Gate Array

    Yoji NISHIO  Hideo HARA  Masahiro IWAMURA  Yasuo KAMINAGA  Katsunori KOIKE  Kosaku HIROSE  Takayuki NOTO  Satoshi OGUCHI  Yoshihiko YAMAMOTO  Takeshi ONO  

     
    PAPER-Integrated Electronics

      Vol:
    E78-C No:9
      Page(s):
    1255-1262

    A 0.5 µm CMOS embedded function type gate array family with high speed modules was developed. This family has: an effective basic cell; high speed, compiled type metallized and diffused RAMs; PLL (Phase Locked Loop); and GTL (Gunning Transceiver Logic) to realize operation of over 100 MHz at 3.3 V. This paper describes the basic cell architecture and the compiled type metallized RAM. A divided MOS transistor type basic cell is effective for metallized modules such as metallized RAM and internal logic circuits. The appropriate basic cell size (height) can be decided from the viewpoints of the relationship between the number of usable basic cells and the basic cell height, and the logic circuit speed. Propagation delay time of the 2-input NAND is 200 ps at a standard load of fan out=2 and metal length=1.4 mm. For the universal ASIC, the compiled RAM is indispensable. Single port and multi-port metallized RAMs which are structured by using the basic cells are discussed. The new single port memory cell circuit which has a differential write and single end read operating method is introduced. This memory cell circuit can be realized using one basic cell. The diffused layer region of the NMOS transfer gates for the read operation is shared between neighbor memory cells. So, the capacitance of the bit line becomes smaller, and a high speed access time can be achieved. The measured access time of 1 kbits is 4.2 ns. The new multi-port memory cell circuits which have a single end write and single end read operating method are introduced. The read operating method is the same as that of the single port memory cell circuit. The access time shows very high speed operation comparable to that of the single port memory. This 3F (Flexible, Fast, and Friendly) ASIC family can be applied to high speed processors in workstations and graphics equipment.

  • BiCMOS Circuit Techniques for 3.3 V Microprocessors

    Fumio MURABAYASHI  Tatsumi YAMAUCHI  Masahiro IWAMURA  Takashi HOTTA  Tetsuo NAKANO  Yutaka KOBAYASHI  

     
    PAPER

      Vol:
    E76-C No:5
      Page(s):
    695-700

    With increases in frequency and density of RISC microprocessors due to rapid advances in architecture, circuit and fine device technologies, power consumption becomes a bigger concern. Supply voltage should be reduced from 5 V to 3.3 V. In this paper, several novel circuits using 0.5µm BiCMOS technology are proposed. These can be applied to a superscalar RISC microprocessor at 3.3 V power supply or below. High speed and low power consumption characteristics are achieved in a floating-point data path, an integer data path and a TLB by using the proposed circuits. The three concepts behind the proposed high speed circuit techniques at low voltage are summarized as follows. There are a number of heavy load paths in a microprocessor, and these become critical paths under low voltage conditions. To achieve high speed characteristics under heavy load conditions without increasing circuit area, low voltage swing operation of a circuit is effective. By exploiting the high conductance of a bipolar transistor, instead of using an MOS transistor, low swing operation can be got. This first concept is applied to a single-ended common-base sense circuit with low swing data lines in the register file of a floating and an integer data path. Both multi-series transistor connections and voltage drops by Vth of MOS transistors and Vbe of bipolar transistors also degrade the speed performance of a circuit. Then the second concept employed is a wired-OR logic circuit technique using bipolar transistors which is applied to a comparator in the TLB instead of multi-series transistor connections of CMOS circuits. The third concept to overcome the voltage drops by Vth and Vbe is addition of a pull up PMOS to both the path logic adder and the BiNMOS logic gate to ensure the circuits have full swing operation.