Designer-view
From Circuitopedia
Circuit-O-pedia: Circuit Open Encyclopedia
The designer view
The Naive Hypothesis
- Together, let's make analog/RF circuit knowledge reusable.
- Put in your knowledge on Circuitopedia and tap the collective knowledge of other designers.
- Get existing simulation resources for a circuit and add if you build your own. Save time and effort.
- Get a community check-point to see if you are doing it right and help in evolution of standards.
- Easily traverse through hierarchical decompositions of circuits and do better system level design.
- Make analog design better, faster, easier and intellectually more stimulating.
A more serious thought-basis
The design process: An art
Analog circuit design is considered an art. Why so? Because every circuit topology is a new system in itself with beautiful and interesting emergent properties resulting from an interconnection of non-linear and linear devices. Though the basic principles of the elements are well-understood (probably, not any more at 65nm) and can be stated compactly, the emergent properties of each topology is different, not always completely captured in math and understood by different people differently. Also, the problem of sizing a circuit for given specifications not being invertible make the design process heuristic. Layout adds another level of complexity. This makes analog design an art form. Every designer does it differently!
The nature of the field has kept the intellectual quotient high, but greatly hampers any kind of re-use. This leads to long design cycles, re-calculation, re-discovery of design principles, also sub-optimal designs and failures. But now we can re-use this knowledge using the fabric of World-Wide-Web which connects all of us. We can all contribute to and learn from a universally accessible resource-pool, leading to reuse! Here is the new picture of the circuit world:
A new stimulating intellectual Environment: How interesting will it be to share more than one perspective to understand a circuit. You will have a design methodology, someone else will have a different one. Both of them will be on Circuitopedia. Is there something you were missing which the other one covered or vice-versa. Can the mutliple views now lead to a different methodology? The rule is not to start from scratch and reinvent, but get a starting point for the design methodology! Same goes for layouts.. Leading to a new stimulating intellectual environment.
Reusable equations in various forms: Writing equations for circuits is generally a mess. Symbolic-analyzers have failed to come up with anything which is human-comprehensible. When we do it, we approximate, but where to approximate and how much to? We all end up using different equations. And then the time overhead... How about when Harry calculates these equations, Pankaj could use them. There is anyway no fun or intellectual satisfaction in solving a circuit for its equations... Pankaj can use these equations, put his version up if unsatisfied and put a comment on why the approximation does not work. Also, if Harry was not concerned about the noise in the circuit, but Pankaj is, now it is Pankaj's chance to contribute. This dynamics now builds a database of equations for different topologies with different level of accuracy and comprehensibility. We re-use, help each other and build on top of this.
Hierarchy, decomposition and System-level Design: Circuits for analog design are hierarchically linked. An ADC contains amplifiers; amplifiers contain opamp and passive components; simple opamp contains a differential stage and a single-ended amplifier; the amplifiers contain current mirrors and common-source stage. This hierarchy decomposes the problem into pieces for easier design and help explore alternative topologies. Circuitopedia links up circuits by their hierarchical decomposition. Now you could choose to replace a simple current mirror with a cascode in an opamp and quickly traverse to the new resultant opamp. Properties and features of lower-level blocks would inform which one to choose for a higher-level block. Preserving hierachies, traversing across topologies, comparing topologies, inventing topologies (by replacing sub-circuits) and making a wise decision for system level design will have a new meaning with Circuitopedia.
The return of analog?: This is a bold claim to make, but isn't it true that apart from some minor reasons, the win of digital over analog has been largely due to its re-usability and low time-to-market (priority 1 in SOC industry). Put another way, even if we design extremely efficient analog circuits, analog circuits cannot become ubiquitous, till they can be designed quickly and without failures. To deliver the promise of their efficiency (which showed-up with neuromorphic circuits and sub-threshold circuits), we need to emancipate analog design from long design cycles and design failures. Circuitopedia can facilitate this just by straightforward cooperation and sharing among analog designers. The knowledge to design good analog circuits fast is there, it just needs to be shared.
The design resources: A mess
How much fun is it to draw the schematic of a 40 transistor circuit, or worse still writing its netlist. Are you ever confused whether the expression you wrote to measure settling-time is correct, are you missing on anything which you should check, or what about the phase margin, or you are unsure about the corners to check.
Circuitopedia is a answer to lot of these time-consuming and non-standardized ways of doing circuit simulation. Circuitopedia apart from circuit knowledge also contains the simulation resources. You can find the netlist of your circuit here and if it is not, please do not forget to put one in here when you make it. It will save Harry trouble next time he wants to do the same circuit. Also, the way to measure circuit specifications for various SPICE packaging is included on Circuitopedia. We believe as more and more analog designers use Circuitopedia standards would emerge to measure circuit specifications. Again leading to fast and error-free design.
If there are other circuit simulation resources, which Circuitopedia doesn't include, let us know and we will have them incorporated in Circuitopedia. Also read the later prospects of Circuitopedia to become a much stronger vehicle for CAD software here.
