Stick diagrams





Stick diagrams can also be used to plan out a circuit. For example, the XOR circuit in section 8. In previous sections, the stick diagram for the NAND, NOR, and INVERTER were already created. When drawing a circuit, space is always a prime concern. To reduce space, the diffusion should be broken as little as possible, and power connections should be shared as often as possible. With VSS and VCC power connections directly over each other, they can be shared between logic gates to same space. Interconnect should also be short. The NAND gate goes directly into the INVERTER. This INVERTER is an input for one NOR gate, who’s other input is the second NOR gate. `NAND --> INV --> NOR <-- NOR` And remember that each stick diagram can be “flipped.” Keeping this in mind, first place the stick diagrams down without interconnect. Just share the power at first, trying to match the above planned order. Now connect the circuit. Notice how the output of the NAND gate is the input for the INVERTER. Also notice that one NOR gate has that INVERTER as one of it’s inputs, and the other input is another NOR gate. This is the finished stick diagram. We were forced to break each diffusion once, but share the power. The interconnect is also nice and short.