In ASIC fabrication, it is sometimes necessary to implement an isolation barrier for the purpose of noise isolation or to allow the use of multiple power supply rails. A Deep N Well is the N doping into a P-type substrate that gets implanted deeper than a “standard” N well. The deeper implantation allows a larger depletion region at the PN junction around the N well. This produces a greater level of isolation between the device(s) created in the N well and the substrate. As an example, in a mixed-signal ASIC, analog circuitry can be implemented using +/- 5V power supplies if the substrate is biased at -5V. Then, digital circuitry can be implemented in a Deep N Well using 1.8V transistors with a 1.8V power supply referenced to 0V. The Deep N Well provides isolation between the -5V substrate and the 1.8V supply to allow the use of 1.8V transistors.

Triad has vast experience with ASIC designs that include analog and digital (mixed-signal) functions. Additionally, Triad engineers work in process nodes that support high voltage analog up to and exceeding 80V.