0x213 Digital Circuits

Combinatorial logic

Gates

Gate (NAND) $\neg{(A \land B)}$

Any gate can be implemented from NAND

TTL 7400 CMOS 4011

CMOS implementation

Reference: wikipedia

Adder

Adder (half adder) 2 input, 2 output. xor for sum, and for carry

Adder (full adder) 3 input, 2 output half adder + carry in

Multiplier

Sequential Logic

Latch

SR Latch

  • two nor gate (active high)
  • two nand gate(active low)

Gated SR Latch

  • add a gate to SR Latch

Gated D Latch

  • S, R are merged into D bus

Oscillator