What should Hardware Engineer focus on? - Simulation or Calculations?

 

One of the major problems hardware engineer face is that the result of their design is only seen post the design unlike the firmware engineer who could visualize their output during the design. What we mean to say here is that everything is not black and white for Hardware Engineer. To explain with a scenario, what looks like an working evaluation board doesn't get replicated in the original design. Some of the major problems are,

• Dependency of many external factors - Fabrication, components, Assembly

Keeping the external factors aside, it is the responsibility of the Hardware engineer to keep a tab on the things under his control. The circuit design these days is reused from vendors, evaluation boards, older designs, etc. If a new design need to be done from scratch, this is where most of the design engineers falter. Most of the engineers rely on simulation tools which again is based on several approximations. If we take an example of model of a component used for simulation, it is not exact replica of the real component. The actual working functionality may not be really tested in simulation. For example, if we want to simulate a digital circuit with some protocol data input, it is not so straight forward. The only point we want to make here here is that result out of simulation cannot be treated black and white. Designer has to use his intuition to look into factors which were not considered in simulation. Calculations on the other side provide more of theoretical insight into the design but the actual real component behavior scenario can be achieved. Some smart designers take a hybrid approach of performing theoretical calculations and then using the simulation means to re verify the design.

Let us explain the above with a simple example. Let us seethe calculation of collector current  of a BJT with a current gain B. The relation is Ic = B * Ib. When we theoretically calculate the relation looks straight forward but when we perform simulation, the biasing condition, the base voltage and current, play a role in the design. 

One can say at component level, calculations are preferred but at the integration level, it is only simulation which can help. How simulation and calculation results are understood and design is improved is left to the tips and tricks of the engineer.