System Architecture

Customer Requirements

The Customer requirements leading to a mixed-mode(1) Asic may be very diverse. It will very much depend if the customer has experience about dealing with Asic designs before.  
Roughly we may grade this into 4 basic patterns:

  • The customer is having a basic idea about an innovative product without too much details.
  • The customer has a very concrete idea about an electronic circuit that he would like to realize into an Asic, including commercial aspects as volumes and pricing level. The idea is sketched on paper with some basic operation modes and some basic requirements.
  • An existing working electronic breadboard is available and the customer would like to have this board realized into one Asic.
  • The customer has an existing Asic but would like to make the next generation of this device. The specs of the existing device are available. 

Depending on the level of “maturity” of the idea the approach we follow is different.  
Approach for a) and b) are very similar though for a) some more preparatory discussions and work is needed. 
For type a) we have to get the system requirements of the customers’ idea properly defined. Questions like: what is the system supposed to do and what not? What is the typical application and what would be the desired specifications of the system? To answer these questions the marketing department of the customer needs to be involved. What are the forecasted volumes at what sales price? Outcome of the exercise is a basic requirement list with prognosis of volumes and sales price.  
If the elements of a) are clear we go to b) 
As we are targeting a mixed-mode Asic we should translate the concrete idea into an architectural model of how the asic should look like. Questions as: what components to be put in the Asic and what components should be outside? What are the specification requirements of the different building blocks? Are these specification feasible with “normal” (2) IC building blocks?  Different architectures may be put forward. Selection of the most appropriate architecture may be done on either feasibility base, cost base, risk base etc. To evaluate the risk of different architectures one may use a system FMEA (3) elaborated by a multidisciplinary team of the customer together with the Asic consultant.  Outcome of the exercise is a basic architecture of the chip with building blocks and specification of the blocks,  number of pins and external components.  Once this is approved this may be the start of a breadboard. 
If the elements of b) are clear we go to c) 
In case the customer has made his own breadboard we can base ourselves on that. However it is perfectly possible that the architectural design of the breadboard is not well suited to be integrated into an Asic. In that case we have to go back to phases b) or eventually a) if these elements were skipped in the customers’ process. 
If the appropriate chip architecture has been defined see process for case b) the Asic oriented breadboard can be build. Link to breadboard. Of course this breadboard needs to be tested in the environment and conditions it has to work. This may pose quite some challenges (4 examples link) 
In case d) if an existing Asic is used as a starting base, one needs to make clear what are the reasons for the redesign. Either it can be a cost improvement or  it may be extending the functionality of the Asic, obsolescence of the existing device etc. Depending on the level of preparative work done by the customer one may need to rework some of the system requirements or the basic architecture of the chip. Depending on the evaluation of all that it will be decided if a new breadboard is required or not.  
See diagram scanned where these text can be put under or it can be extra explanation…
Links to be clicked:

  • Mixed mode in the definition of ICR is a design that has both analog and digital circuitry on board. The amount of  Analog circuitry is ranging from 20% of the chip area till 90%...
  • With normal we mean standard analog building blocks like opamps, comparators, A/D, D/A, bandgaps, sensors etc…When one needs very accurate “laser” trimmed and expensive components, the feasibility would look different.
  • FMEA: failure mode and effect analysis. A methodology used in automotive industry that can be deployed to verify the impact of different failure modes onto a given system architecture. Comparing different architectures with FMEA would lead to the lowest risk implementation.
  • Give some examples of size problems, current consumption etc.
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