经典IC设计面试问题12

yanzhang98 · 发表于 2010-11-28 07:13:16

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What are Different types of Verilog Simulators ?

There are mainly two types of simulators available.

Event Driven
Cycle Based

Event-based Simulator:

This Digital Logic Simulation method sacrifices performance for rich functionality: every active signal is calculated for every device it propagates through during a clock cycle. Full Event-based simulators support 4-28 states; simulation of Behavioral HDL, RTL HDL, gate, and transistor representations; full timing calculations for all devices; and the full HDL standard. Event-based simulators are like a Swiss Army knife with many different features but none are particularly fast.

Cycle Based Simulator:

This is a Digital Logic Simulation method that eliminates unnecessary calculations to achieve huge performance gains in verifying Boolean logic:

1.) Results are only examined at the end of every clock cycle; and
2.) The digital logic is the only part of the design simulated (no timing calculations). By limiting the calculations, Cycle based Simulators can provide huge increases in performance over conventional Event-based simulators.
Cycle based simulators are more like a high speed electric carving knife in comparison because they focus on a subset of the biggest problem: logic verification.
Cycle based simulators are almost invariably used along with Static Timing verifier to compensate for the lost timing information coverage.