Analog integrated circuit simulator Semisim by Brandon L Destefano runs in the browser, and helps design semiconductor devices such as transistors and diodes on an IC die.
The tools work on the principle that initially a user can select the tool and what they wish to draw, to create an interactive diagram on the circuit that can then be simulate.
While resistors are often thought of as being sloppy in terms of component precision in a real world circuit, in an IC they are actually the more sloppy component, while capacitors have a tightly controlled plate-size, allowing very precise ratios between two capacitors.
The simulator shows these principles in action and also provides examples such as a ring oscillator or a DRAM cell users can build upon.
