Difference between discrete design (PCB) and VLSI circuits(IC’s).

The basic difference between PCB and IC design is that PCB is simple.

DISCRETE DESIGN	IC’s
No. of components cells 10-100.        Uses fabricated components.        Data sheets are used for the circuit      design.        No design matching.        Large area.        More power required.        High cost.        Less time to design.	No of components large (million-billion).     Designed and given for the fabrication.     Spice modules are used for the circuit design.     Design matching requires.     Very less area.     Low power.     Cost effective.     More time to design.     Can design 1000’s of PCB design within one chip.

VLSI FLOW

It is the hierarchy levels of process through the industry to fabricate the chip.

Mainly there are three important flows.

•     Full custom flow.
•     ASIC flow.
•     FPGA.

FULL CUSTOM FLOW

Full custom is designing of basic components to build the circuit. Designing starts from the scratch.

It contains the deriving of resistors, capacitors, inductors, transistors etc..,

Full custom flow can be implemented to the following designs.

       I.            Digital circuits

A.     Standard cells.

B.     Memories.

C.     Inputs and outputs.

    II.            Analog circuits

A.     Op-amp.

B.     ADC/DAC.

C.     PLL.