FAQ's

Under construction

1. Can I see some screen shots of PAK on this site please?

Yip here. The are all from the spreadsheet or the PAK User Guide.  

Mouse-over shows the sheet it came from. EG "Fig4s2aCCT" is the circuit found on Sheet 4.

The "4s2a" means Section 4.2 in the User Guide.

 

The following shots are provided:

  • Common emitter stage with shunt feedback and emitter degeneration
  • Current source with feedback
  • Basic common emitter push-pull output stage

2. I'm interested in designing audio power amplifiers. Can the PAK project help me?

Probably not for some time. It will take a while for the PAK project to solve and collect enough circuits and helpful information for any designer to design power amplifiers. See the Goals page for a roadmap.

3. I'm interested in helping with the PAK project. What can I do to help?

  1. See the Goals page to get an idea of what can be done.
  2. Read the User Guide Preface to see if you are still interested in this type of project. If you are then read the User Guide.
  3. Read UG Chapter 4. It shows how equations are developed and you can run the LTspice circuits to get a feel for how they can be formulated. You may find better ways to do this, such as MathLab or an equivalent environment.
  4. If have a circuit you want to solve then try and break it down to smaller sub-blocks and check if they have already been solved, otherwise start on one of your sub-blocks.
  5. You can use this sites Contact and Forum for support, or start up your own site and Forum.

4. Why bother learning the Lambert W approach? Is there a payoff?

  • No. But if you are like me you might like the 'challenge' of doing something no one else has done. But beware, there's no guarantee that you can or will succeed. Most of our circuits still can't be solved, at least until the mathematicians find new ways for us.
  • And if you like circuit analysis and have a lot of spare time on your hands and are not worried about earning nothing from it then the PAK project would be a great hobby.
  • But if you are a young analog engineer and would like to develop a new skill of solving circuits using Lambert W then it could give you an edge over other designers (see El.Wkly 2006 http://www.electronicsweekly.com/Articles/2006/06/27/39017/Good-analogue-design-is-key-to-success-says-Intersil.htm).

5. Are you trying to build a mini SPICE simulator or do away with SPICE altogether?

No. That was not the intention with the PAK project. The PAK spreadsheet may look like a simulator because it produces plots like a simulator. But the spreadsheet plotting aspect is to demonstrate what the equations can do without using a SPICE engine (the numerical equation solver). A PAK spreadsheet cannot solve arbitrary circuits like a simulator, so a SPICE numerical solver will always be needed. The PAK equations used in the spreadsheet show that some circuits can be calculated using explicit equations for bipolar transistor amplifiers, like Iout=Function(Vin, all component values).  

 

On the contrary, if simulators (or Math-Cad packages) include some (or all) the equations developed by the PAK project then the PAK spreadsheet is no longer needed.  For example, some circuit blocks (like mirrors or constant current sources) can now be represented by a compact code model equation set within the SPICE simulator. This reduces the matrix size which can make simulators run faster and more robust.

6. How did you (Ian Hegglun) get interested in solving equations for power amplifiers?

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