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Circuit 4: Four-Bit Adder

The following file simulates a four-bit binary adder, using several subcircuits to describe various pieces of the overall circuit.

    ADDER - 4 BIT ALL-NAND-GATE BINARY ADDER
    *
    *** SUBCIRCUIT DEFINITIONS
    .SUBCKT NAND 1 2 3 4
    *NODES: INPUT(2), OUTPUT, VCC
    Q1 9 5 1 QMOD
    D1CLAMP 0 1 DMOD
    Q2 9 5 2 QMOD
    D2CLAMP 0 2 DMOD
    RB 4 5 4K
    R1 4 6 1.6K
    Q3 6 9 8 QMOD
    R2 8 0 1K
    RC 4 7 130
    Q4 7 6 10 QMOD
    DVBEDROP 10 3 DMOD
    Q5 3 8 0 QMOD
    .ENDS NAND
    .SUBCKT ONEBIT 1 2 3 4 5 6
    *NODES: INPUT(2), CARRY-IN, OUTPUT, CARRY-OUT, VCC
    X1 1 2 7 6 NAND
    X2 1 7 8 6 NAND
    X3 2 7 9 6 NAND
    X4 8 9 10 6 NAND
    X5 3 10 11 6 NAND
    X6 3 11 12 6 NAND
    X7 10 11 13 6 NAND
    X8 12 13 4 6 NAND
    X9 11 7 5 6 NAND
    .ENDS ONEBIT
    .SUBCKT TWOBIT 1 2 3 4 5 6 7 8 9
    *NODES: INPUT - BIT0(2) / BIT1(2), OUTPUT - BIT0 / BIT1,
    *       CARRY-IN, CARRY-OUT, VCC
    X1 1 2 7 5 10 9 ONEBIT
    X2 3 4 10 6 8 9 ONEBIT
    .ENDS TWOBIT
    *
    .SUBCKT FOURBIT 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
    *NODES: INPUT - BIT0(2) / BIT1(2) / BIT2(2) / BIT3(2),
    *       OUTPUT - BIT0 / BIT1 / BIT2 / BIT3, CARRY-IN, CARRY-OUT, VCC
    X1 1 2 3 4 9 10 13 16 15 TWOBIT
    X2 5 6 7 8 11 12 16 14 15 TWOBIT
    .ENDS FOURBIT
    *
    *** DEFINE NOMINAL CIRCUIT
    *
    .MODEL DMOD D
    .MODEL QMOD NPN(BF=75 RB=100 CJE=1PF CJC=3PF)
    VCC 99 0 DC 5V
    VIN1A 1 0 PULSE(0 3 0 10NS 10NS   10NS   50NS)
    VIN1B 2 0 PULSE(0 3 0 10NS 10NS   20NS  100NS)
    VIN2A 3 0 PULSE(0 3 0 10NS 10NS   40NS  200NS)
    VIN2B 4 0 PULSE(0 3 0 10NS 10NS   80NS  400NS)
    VIN3A 5 0 PULSE(0 3 0 10NS 10NS  160NS  800NS)
    VIN3B 6 0 PULSE(0 3 0 10NS 10NS  320NS 1600NS)
    VIN4A 7 0 PULSE(0 3 0 10NS 10NS  640NS 3200NS)
    VIN4B 8 0 PULSE(0 3 0 10NS 10NS 1280NS 6400NS)
    X1 1 2 3 4 5 6 7 8 9 10 11 12 0 13 99 FOURBIT
    RBIT0 9 0 1K
    RBIT1 10 0 1K
    RBIT2 11 0 1K
    RBIT3 12 0 1K
    RCOUT 13 0 1K
    *
    *** (FOR THOSE WITH MONEY (AND MEMORY) TO BURN)
    * Ah, the good olde days...
    .TRAN 1NS 6400NS
    .END



Stephen R. Whiteley 2017-11-08