The other day I was watching how TB works in RX7 and was surprised how it was designed. Basically there are 3 plates and one opens first and second and third follows it later, it's all mechanical. Apparently it was designed to increase air velocity at low RPMs for more linear acceleration through out the RPM range.




Same trick can be used in Drive-by-wire TB but with single much larger plate, computer can limit throttle angle in reference to engine RPM to keep power more linear.