One of my competitors claim that their wideband controllers are digital because of the way their controller drives the lambda sensor Pump Cell. Their wideband controller is digital and it has nothing to do with how the Pump Cell is driven.
The difference between analog and digital is how math is done, You can do math with analog circuitry and in the early to mid 90s opamps, operational amplifiers, were the Arduino of it's time and thus math was done using opamps for cheap electronic goods.
All wideband controllers on the market today are digital except perhaps controllers built around the Bosch CJ125 IC, I believe the CJ125 internally uses opamps to do math,
